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Submarine channel formation and acoustic remote sensing of suspended sediments and turbidity currents… Hay, Alexander Edward 1981

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SUBMARINE CHANNEL FORMATION AND ACOUSTIC REMOTE SENSING OF SUSPENDED SEDIMENTS AND TURBIDITY CURRENTS I N RUPERT I N L E T , B.C.  by  ALEXANDER EDWARD HAY B. S c . , U n i v e r s i t y  of Western O n t a r i o ,  1971  M. S c . , U n i v e r s i t y  of Western O n t a r i o ,  1972  A THESIS SUBMITTED I N PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE DEPARTMENT OF  OCEANOGRAPHY  We a c c e p t t h i s t h e s i s a s c o n f o r m i n g to the required  standard  THE UNIVERSITY OF B R I T I S H COLUMBIA S e p t e m b e r 1981  © A l e x a n d e r Edward Hay, 1981  In p r e s e n t i n g  this  thesis i n partial  f u l f i l m e n t of the  r e q u i r e m e n t s f o r an a d v a n c e d d e g r e e a t t h e U n i v e r s i t y of B r i t i s h Columbia, I agree that it.freely  the Library  a v a i l a b l e f o r r e f e r e n c e and s t u d y .  agree that p e r m i s s i o n f o r extensive for  s c h o l a r l y p u r p o s e s may  for  financial  shall  fJr  eewt0$  The U n i v e r s i t y o f B r i t i s h 2075 W e s b r o o k P l a c e V a n c o u v e r , Canada V6T 1W5 Date  n r .  0.  I0  /"7Q ^  further thesis  Itis thesis  n o t be a l l o w e d w i t h o u t my  permission.  Department o f  make  be g r a n t e d by t h e h e a d o f my  copying or p u b l i c a t i o n of this  gain  I  copying of t h i s  d e p a r t m e n t o r by h i s o r h e r r e p r e s e n t a t i v e s . understood that  shall  /z?  Columbia  written  ABSTRACT T u r b i d i t y c u r r e n t s , both continuous h a v e been d e t e c t e d and  200,  kHz.  discharge  and  the  from  The  turbidity  to  Rayleigh  1000  mg  target) amplitude, of  Estimates  cm  the  1~ . theory  and  linear  shape  relation  to  is  s" .  The  1  in  density  current  e x c e s s d e n s i t y of one  reverberation  a  amplitude  the  t o be  heads  to  g cm" .  from  The a d d i t i o n a l  3  may Thermal  based  estimated  currents  be  plume.  r a n g e f r o m 30  in  and  standard  a  s u r g e was 0.12  with  on  suspended p a r t i c l e s  little  to a  discharge  s o u n d waves by  particulate concentration.  kHz  cross-sectional  a t t e n u a t i o n of turbidity  relation  consistent  (relative  generate  concentration  for  the  a c o u s t i c s i g n a l a t 200  i n f o r m and  i s used  sediment  107  suspended p a r t i c u l a t e c o n c e n t r a t i o n This  1  A  of s u r g e s p e e d s f r o m t h e a c o u s t i c r e c o r d s  universal 120  i n t o Rupert I n l e t .  power of  scattering  profile  surge-type,  c u r r e n t s are a s s o c i a t e d w i t h  between the b a c k s c a t t e r e d  one-half  10  and  w i t h a c o u s t i c s o u n d e r s o p e r a t i n g a t 42.5,  of m i n e t a i l i n g  is obtained  flow  is  important  used t o estimate  suspended  processes  contribute  very  t o t h e a d d i t i o n a l a t t e n u a t i o n by p a r t i c l e s w i t h t h e  grain  d e n s i t i e s of common m i n e r a l s . A tailing deposit buried  leveed  submarine channel  discharge as  ( o u t f a l l ) over  early  i n 1978,  and  as by  1976-77, t h e o r i g i n a l upper (l°  reach  slope)  "increasing  with  with in  an  1974. late  The 1979  channel  extended from the p o i n t of the  upper reach a new  curvature  meanders with  of  had  (1)  of 2.2°,  a  tailing  system  developed.  was In  left-hooking  (2) a m i d d l e  (700-1100 m  distance  the  of t h i s  channel  consisted of:  average slope  pronounced  surface  the  reach  wavelengths)  downstream  and  (3)  a  straight the  lower  channel  increase  km  in  (0.5°  decreased  i n the  about 5 . 5 plume  reach  first  from the  bends  s l o p e ) . The  with  area  m,  outfall.  until  the  Acoustic  overspill  channel  records  of the  from the o u t e r  discharge  bank and  o f t h e u p p e r i n t e r f a c e away f r o m t h e c e n t r e of  curvature.  The  interfacial  difference in  together  with observed t i d a l  in  upper  the  slope  reach  is  i s steeper  levee  currents  been s u g g e s t e d f o r d e e p - s e a  gravity  cores  from  the  levees  v e r t i c a l l y - g r a d e d , C u - r i c h and w h i c h have l o a d - c a s t e d basai  contacts.  column  with  building important, lower  reach  intervals c o r e and  down-channel,  as  thickness  from  present  from continuous  d are  turbidity obtained  surges.  given  by  seismic  changes  in  of  some  of  at  sediment  that  levee-  f l o w becomes l e s s through  Surge  turbidity  surge recurrence  the  recurrence  f r o m t h e number t u r b i d i t e s  in  reflection  latter  tailing  water  depth,  surveys,  and  intervals.  deposit  per 0.3-  ranged from in  tailing  in  diatom turbidity  is applied  Results are c o n s i s t e n t with a  b u d g e t b a s e d on c h a n g e s i n t h e  their  of the  submarine c h a n n e l s i n c l u d i n g entrainment  the Rupert I n l e t channel.  that  layers  f r u s t u l e a b u n d a n c e i n t h e c o r e s . A m o d e l of c o n t i n u o u s flow  to  as silt,  more  hook  in  suggesting  l o c a l d e p o s i t i o n r a t e . The  4 m yr~ ,  left  Turbidites  t h a t most o f t h e m a t e r i a l t r a n s p o r t e d  2-5  of  channels.  comprise  bend  records  suggest t h a t the  F e - p o o r s a n d and  layers  i s c a r r i e d by  the 1  These  overbank s p i l l a g e  and  These  f l a m e - s t r u c t u r e s or l o a d - p o c k e t s  distance  by  heights.  are  an  t h a n i n d i c a t e d by  c a u s e d by a m e c h a n i s m s i m i l a r  w h i c h has  an  disappeared  upward t i l t  the cross-channel  of  d i s t a n c e downstream, e x c e p t i n g  100-200  indicate  cross-sectional  to  sediment  v o l u m e , and  with  iv  (a)  (b) Turbidity Current  Channel h—H  1312  1320  H-H  T  1322  1327  1332  PDT  F r o n t i s p i e c e - Echograms a t 200 kHz o f a t u r b i d i t y c u r r e n t f l o w i n g w i t h i n a s u b m a r i n e c h a n n e l i n R u p e r t I n l e t on A u a u s t 26, 1976. ( a ) f i r s t c r o s s i n g , c h a n n e l empty;' ( b ) s e c o n d crossing' t u r b i d i t y c u r r e n t f i l l i n g c h a n n e l and waning i n t h i r d and f o u r t h c r o s s i n g s ( c and d ) .  V  TABLE OF CONTENTS ABSTRACT  i i  L I S T OF TABLES  x  L I S T OF FIGURES  xii  ACKNOWLEDGEMENTS  xxi i i  Chapter 1  INTRODUCTION  1  1.1 The M i n i n g  7  Operation  1.2 P r e v i o u s Work i n R u p e r t 1.2.1 P h y s i c a l  8  Inlet  8  Oceanography  9  - 1.2.2 S e d i m e n t s 1.2.3 E n v i r o n m e n t a l I m p a c t S t u d i e s  10  2 SOUND SCATTERING AND ATTENUATION I N SUSPENSIONS  11  2.1 The I n v i s c i d , N o n - c o n d u c t i n g C a s e 2.1.1  14  S o l i d Sphere  14  2.1.2 F l u i d S p h e r e  16  2.1.3 S o l i d S p h e r i c a l S h e l l  17  2.2 V i s c o t h e r m a l E f f e c t s . 2.2.1  18  Governing Equations  19  2.2.2 G e n e r a l S o l u t i o n  23  2.2.3 The B o u n d a r y - V a l u e P r o b l e m  26  2.3 The I n v i s c i d N o n - C o n d u c t i n g L i m i t  29  2.4 The L o n g - W a v e l e n g t h L i m i t  30  2.4.1  The I s o t r o p i c • (n=0) Term  2.4.2 The D i p o l e  30  ( n = l ) Term  31  2.4.3 The A t t e n u a t i o n o f t h e I n c i d e n t Wave  31  2.4.4 C o m p a r i s o n w i t h E x p e r i m e n t  33  '  vi  2.5  Summary  37  3 DETECTING SUSPENDED SEDIMENT WITH SONAR:THEORY EXPERIMENT 3.1  Theory 3.1.1  B a c k s c a t t e r i n g from a S i n g l e S c a t t e r e r  43  3.1.2  B a c k s c a t t e r i n g from a Cloud of P a r t i c l e s  44  3.1.3  The  48  3.1.4  Standard  Sonar E q u a t i o n Targets  Experimental Apparatus  3.3  A n a l y s i s and  4 THE  52 and  Procedures  Results  53 58  3.3.1  Suspended Sediment A n a l y s i s  60  3.3.2  A n a l y s i s of A c o u s t i c S i g n a l s  64  Discussion  75  3.4.1  Signal Statistics  75  3.4.2  Comparison w i t h P r e v i o u s S t u d i e s  78  3.4.3  Other  R e v e r b e r a t i o n Mechanisms  78  THE  83  MORPHOLOGY OF  T A I L I N G DEPOSIT  4.1  The  4.2  Bathymetric  4.3  M e a n d e r i n g C h a n n e l Regime  R e s u l t s of E a r l i e r and  Surveys  Seismic Surveys  4.3.1  Upper R e a c h  4.3.2  M i d d l e - R e a c h : The  4.3.3  Lower R e a c h  88  96 Meanders  The  A p r o n Regime  4.5  Rechannelized  4.6  C o m p a r i s o n w i t h Deep-Sea F a n - V a l l e y s  Regime  5 SEDIMENTS  99 106 109 114 121 128  Sampling 5.1.1  83  95  4.4  5.1  40 43  3.2  3.4  AND  and  Laboratory Techniques  Size Analysis  128 130  vii  5.1.2  Grain Density  132  5.1.3  Metal Analysis  133  5.2 S u r f i c i a l  Sediments  134  5.2.1  C h a n n e l i z e d Regime  134  5.2.2  Surficial  S e d i m e n t s : A p r o n Regime  137  5.2.3  Surficial  S e d i m e n t s : R e c h a n n e l i z e d Regime  140  S e d i m e n t s : Summary  142  5.2.4 S u r f i c i a l  5.3 The S e d i m e n t Column 5.3.1  144  The C h a n n e l i z e d Regime  148  Upper R e a c h  150  M i d d l e Reach  153  Lower R e a c h  159  Holberg I n l e t  161  5.3.2  The A p r o n R e g i m e :  Cores  164  5.3.3  D e p o s i t i o n Rates.: T u r b i d i t y Frequencies  Current  167  5.3.4 L a m i n a t i o n Time S c a l e  169  5.3.5  169  Transition  t o t h e A p r o n Regime  6 CURRENT MEASUREMENTS  171  6.1 T a u t - W i r e M o o r i n g s : M e a n d e r i n g C h a n n e l Regime 6.1.1  August  1976 .  6.1.2 November 1976  171 171  "  6.2 O v e r - t h e - S i d e C u r r e n t M e a s u r e m e n t s :  173 A p r o n Regime  6.3 I n t e r p r e t a t i o n 7 THE ACOUSTICAL CHARACTER OF THE DISCHARGE PLUME AND TURBIDITY SURGES 7.1 The D i s c h a r g e Plume  177 182 189 192  7.1.1  M e a n d e r i n g C h a n n e l Regime  192  7.1.2  A p r o n Regime  199  vi i i  7.1.3 7.2  R e c h a n n e l i z e d Regime  Turbidity  7.3  199  Surges  203  7.2.1  M e a n d e r i n g C h a n n e l Regime  203  7.2.2  A p r o n Regime  206  Other Events  216  8 THE SEDIMENT BUDGET AND CHANNELIZED TURBIDITY FLOW 8.1  Sediment Budget  8.2  Two-Dimensional T u r b i d i t y  8.3  222  " "  223 Flow: Theory  226  8.2.1  Surge Flow  226  8.2.2  C o n t i n u o u s Flow  231  Turbidity 8.3.1  8.3.2  Flow and t h e Meandering Channel  235  Upper R e a c h : Mean F l o w  235  F l o w a t C o n s t a n t R i c h a r d s o n Number  237  E n t r a i n m e n t and Sediment T r a n s p o r t i n t h e Upper Reach  239  8.3.3  Lower R e a c h  241  8.3.4  The F r e q u e n c y o f T u r b i d i t y  Surges  242  9 SUMMARY AND CONCLUSIONS  244  BIBLIOGRAPHY  250  APPENDIX 1: THE SCATTERED WAVE  267  A1.1  The i s o t r o p i c  A1.2  Long-wavelength  A1.3'The d i p o l e A1.4  (n=0) t e r m limit  267  (n=0)  268  (n=l) term  Long-wavelength  limit  271 (n=1)  272  A1.5 G l o s s a r y o f s y m b o l s APPENDIX 2: SPECIAL-PURPOSE INSTRUMENTATION AND EQUIPMENT A2.1 A c o m b i n a t i o n s a m p l e r f o r h i g h s u s p e n d e d load environments A2.2  A m o d i f i e d boomerang c o r e r  A2.3  The UBC l a u n c h a n d t h e t r a n s d u c e r mount  273 275 275 276  . . 277  ix  APPENDIX 3: S H I P POSITIONS  279  APPENDIX 4: A SEDIGRAPH MIXING C E L L FOR F I N E SAND AND MUD  283  APPENDIX 5: RESULTS OF SEDIMENT ANALYSES  288  APPENDIX 6: A DIATOM CHRONOLOGY FOR RUPERT INLET SEDIMENTS 293 A6.1 P r i m a r y  productivity  i n Rupert I n l e t  A6.2 S a m p l i n g a n d e x p e r i m e n t a l  295  methods  298  A6.2.1 D i a t o m p r e p a r a t i o n a n d c o u n t i n g  299  A6.2.2 D r y b u l k d e n s i t y  300  A6.2.3 W a t e r s a m p l e s  300  A6.3 R e s u l t s  . ~.  . A6.3.1 The 1978 d i a t o m A6.3.2  300  bloom  300  1979 c o r e s  304  A6.3.3 The 1979 d i a t o m  record  305  A6.3.4 D i a t o m f l u x e s a n d s e t t l i n g A6.3.5 S e d i m e n t a c c u m u l a t i o n A6.3.6 1976 C o r e s : The d i a t o m deposition rates APPENDIX 7: OVER-THE-SIDE  rates:  rates:  1979  1979  307 309  r e c o r d and  CURRENT MEASUREMENTS  312 315  X  List Developments a t t e n u a t i o n of emulsions.  of  i n the sound  Tables theory of scattering in dilute suspensions  and and  13  20°.  33  Characteristics.  54  II -  Physical p r o p e r t i e s at  III  A c o u s t i c Sounder  IV  Results of g r a v i m e t r i c and size f i l t e r e d s a m p l e s . X' i s d e f i n e d i n Eq. the median d i a m e t e r .  analyses, 3.26. d  of is  61  Results of digital processing of tape-recorded a c o u s t i c s i g n a l s . The c o l u m n s l a b e l l e d ' b e f o r e ' and ' a f t e r ' i n d i c a t e t h e s i g n a l l e v e l s b e f o r e and a f t e r each c a s t .  67  VI  Mean s i g n a l levels c r i t e r i o n (3).  68  Vila  Summary o f t h e number of c h a n n e l s o b s e r v e d i n CSP s u r v e y s . The l e t t e r s N and S i n d i c a t e t h a t t h e m a i n c h a n n e l was c l o s e t o t h e n o r t h o r s o u t h w a l l o f t h e inlet.  87  Summary of t h e number o f c h a n n e l s o b s e r v e d in the first 20 ICM s u r v e y s . N = n o r t h s i d e ; S = s o u t h s i d e ; C=centre.  87  VIII  M e a n d e r d i m e n s i o n s i n m. The meander a m p l i t u d e a. The mean v a l u e of L / r i s 3.8 ± 0.4.  106  IXa  Axial slopes w i t h a meander  IXb  A x i a l s l o p e s of s u b m a r i n e c h a n n e l s w i t h either meander r e a c h o r low a m p l i t u d e m e a n d e r s .  X  T a i l i n g mineralogy C a r g i l l (1975).  XI  Deposition recurrence  Xlla  Volume o f t a i l i n g  XII b  Average discharge rates b e t w e e n CSP s u r v e y s .  XIII  Observed mass a c c u m u l a t i o n r a t e s i n the p r o x i m a l z o n e d u r i n g t h e i n t e r v a l b e t w e e n CSP s u r v e y s .  V  VII b  prior  to  ( i n degrees) reach.  applying  rejection  of submarine  f r o m E v a n s and  channels  P o l i n g (1975)  r a t e s and probable turbidity i n t e r v a l s f r o m t h e 1976 c o r e s . d e p o s i t f r o m CSP during  is  no and  current  surveys. the  intervals  1 23 123 •136. 167 225 225 225  xi  Continuous-flow parameters i n the upper reach at line 5 ( l o c a t i o n given i n F i g . 27). Bottom slope=2.2°, c r o s s - s e c t i o n a l a r e a = 4 5 0 m.  239  reach T r a n s p o r t s by . c o n t i n u o u s f l o w i n the upper between l i n e s 2 and 5 ( l o c a t i o n s in F i g . 27). and C r o s s - s e c t i o n a l a r e a s a t l i n e s 2 and 5 a r e 7 00 i n u n i t s of 450 m respectively. Q and Q' are and kg s " respectively. nr s "  239  XV  December 1977  surficial  288  XVI  February  grab  XVII  August  XVIII  1976  cores.  291  XI Xa  1979  core  292  XI Xb  Cu c o n c e n t r a t i o n s i n c o r e  XX  Summary of m a j o r chlorophyll peaks (>2.5 mg n r ) f r o m 5 m a t s t a t i o n A f r o m 1971-1978. The number o f peaks ( b l o o m s ) and t h e mean and s t a n d a r d d e v i a t i o n of c h l o r o p h y l l a a r e shown.  297  Total cell counts of Coscinodiscus spp. and c h l o r o p h y l l a v a l u e s ( f r o m 5 m) a t s t a t i o n A d u r i n g 1974-1976 ( d a t a f r o m S u l l i v a n , 1 9 7 9 ) .  298  XXII  Numbers of diatom S e p t e m b e r 1978.  303  XXIII  Diatoms found i n t r a c e q u a n t i t i e s . The totals column at left are f o r a l l c o r e s , b o t h 1976 1979.  XlVa  2  XI Vb  2  1  XXI  XXIV  1  1979  1979  grab  sediments.  289  samples.  290  samples.  descriptions.  292  79-1B. 3  species  on t h r e e f i l t e r s  from in and  Sediment a c c u m u l a t i o n rates, f o r the 1979 cores based on t h e d i a t o m c h r o n o l o g y . The a v e r a g e v a l u e s do n o t i n c l u d e t h e T -T, e s t i m a t e a t z e r o d e l a y . 3  307  310  xii  List Location site.  map  showing  of  Figures  Rupert  Inlet  and  the  mine  (a) The r a t i o of t h e a d d i t i o n a l a t t e n u a t i o n c o e f f i c i e n t due t o s u s p e n d e d p a r t i c l e s w i t h d e n s i t y 2.65 g cm" t o t h a t i n s e a w a t e r a t 10° C w i t h 30 p p t s a l i n i t y , p l o t t e d a g a i n s t f r e q u e n c y as a f u n c t i o n of p a r t i c l e size, per fractional volume c o n c e n t r a t i o n . Both v i s c o u s and s c a t t e r i n g l o s s e s i n c l u d e d . (b) R a t i o o f a t t e n u a t i o n c o e f f i c i e n t s due t o s c a t t e r i n g l o s s ( x l O ) and v i s c o u s a b s o r p t i o n .  47  Optimum frequency for detection of Rayleigh scattering versus maximum o p e r a t i n g r a n g e i n s e a water at 10 °C with 30 p p t salinity assuming thermal background n o i s e .  51  3  3  (a) S c a n n i n g e l e c t r o n micrograph of l a r g e r p a r t i c l e s after redispersion. (b) S c a n n i n g e l e c t r o n m i c r o g r a p h o f t y p i c a l a g g r e g a t e . Bathymetry locations September, s t a t i o n A.  in August, 1979 showing station and sounding transect occupied in 1979, and Island Copper Mine (ICM)  of size spectral density (a) H i s t o g r a m n ( d p ) d 6 ( + ).. N o t e t h a t points beyond extrapolated by a s s u m i n g t h a t l o g n ( d remains l i n e a r . The i n t e g r a l of (b) H i s t o g r a m of n ( d i s p r o p o r t i o n a l t o the t o t a l volume per 6  P  7 8  10  59  P l o t s of n ( d ) d ^ p  for a l l f i l t e r s .  See  f  60  n(dp) and 80 yum are ) versus d  p  this curve u n i t mass.  Table  IV.  62 63  trace i s the average of t h e b a c k s c a t t e r e d (a) E a c h s i g n a l from n o n - o v e r l a p p i n g s e t s o f 20 consecutive transmissions ( p i n g s ) , o r 10 s e c o n d s of d a t a a t a g i v e n d e l a y ( d e p t h ) . The e c h o e s f r o m t h e b o t t o m and from a large t h e plume a r e i n d i c a t e d , as i s t h a t a m p l i t u d e m o b i l e s c a t t e r e r or ' f i s h ' . tungsten echoes f r o m two(b) T y p i c a l . t a p e - r e c o r d e d 5 table c a r b i d e s p h e r e s ( l o w e r two p a n e l s ) , and tennis balls (upper p a n e l ) . Note t a p e - r e c o r d e r t r a n s i e n t response (T).  65  E c h o g r a m s c o r r e s p o n d i n g t o F i g s . 8a and 10. A=precast recording, sounder gain=5.5; B=post~cast r e c o r d i n g , g a i n = 5.5; C = b o t t l e s i_n s i t u , g a i n = 6.0; D=diel-migrating s c a t t e r i n g l a y e r ; E=top s a m p l i n g b o t t l e ; F = ' f i s h ' i n F i g . 8a.  66  28-point-average time-series centred d e p t h a t s t a t i o n 2 b e f o r e c a s t I . No  at each b o t t l e averaging over  xi i i  successive pings. 11  66  ( a ) N o r m a l i z e d s i g n a l l e v e l s' v e r s u s t h e square root of the p a r t i c l e c o n c e n t r a t i o n . S o l i d l i n e i s v i s u a l best-fit t o t h e d a t a . Broken l i n e i s t h e v a l u e of s' e x p e c t e d on t h e basis of the echo from the standard target, (b) P l o t of s'(rms) versus square root of c o n c e n t r a t i o n . See s e c t i o n 3.4 f o r e x p l a n a t i o n of the broken l i n e .  69  Amplitude statistics plotted as cumulative f r e q u e n c y c u r v e s (+) a g a i n s t a R a y l e i g h - d i s t r i b u t e d probability scale and as frequency histograms. F i g s . 12a-c a r e t h e d i s t r i b u t i o n s o f t h e a m p l i t u d e s in a 2 8 - p o i n t window c e n t r e d a t the delays i n d i c a t e d (28x399 points). Figs. 12d-f are the distributions of the 28-point averages (399 po i n t s ) .  72  ( a ) C o n t o u r s o f s i g n a l l e v e l ( i n 0.5 volt intervals), uncorrected f o r s p r e a d i n g or a t t e n u a t i o n . Grid p o i n t s a r e a t t h e i n t e r s e c t i o n s of horizontal and v e r t i c a l h a s h m a r k s , and r e p r e s e n t a v e r a g e s o v e r 28 points (1m) i n t h e v e r t i c a l and 5 p o i n t s ( 2 . 5 s ) i n the h o r i z o n t a l . (b) Same a s ( a ) , b u t c o n v e r t e d t o c o n c e n t r a t i o n using Fig. 11a a f t e r a p p l y i n g s p r e a d i n g and a t t e n u a t i o n c o r r e c t i o n . C o n t o u r i n t e r v a l i s 500 mg l " .  73  E c h o g r a m c o r r e s p o n d i n g t o F i g . 13. A = t a p e r e c o r d e d pass, sounder gain=5.5; B=third pass, sounder gain=6.0; C=second pass, opposite direction, sounder gain=5.5; D=diel-migrating scattering l a y e r ; p = d i s c h a r g e plume (channelized); X=buoyant c l o u d (see Chapter 7 ) .  74  15  Typical T, S and M (TSP) profiles d i s c h a r g e plume ( s e e a l s o C h a p t e r 7 ) .  81  16  Time s e r i e s o f b a t h y m e t r i c s u r v e y s s h o w i n g ( a ) , t h e m e a n d e r i n g c h a n n e l r e g i m e i n November 1976, (b), the apron regime i n S e p t e m b e r 1978 a n d ( c ) , t h e r e c h a n n e l i z e d r e g i m e i n A u g u s t 1979. C o n t o u r s i n m.  84  17  T a i l i n g thickness i n meters, 29 Heavy l i n e i s t h e c h a n n e l a x i s .  85  18  Tailing  19  Pre-mine bathymetry i n R u p e r t I n l e t . L o c a t i o n s of s e i s m i c r e f l e c t i o n l i n e s (CSP) and t h e m i n e ' s e c h o s o u n d i n g l i n e s (ICM) a r e a l s o shown.  12  13  1  14  20  thickness  through the  November,  i n m e t e r s , 21 O c t o b e r ,  1974.  1975.  B a t h y m e t r y i n November, 1976. To obtain 'true' depths ( z ' ) from depths indicated ( z ) , z'=[(z-  85  86  xiv  3 . 7 ) / I .031 ] c V / C y , where =1483.4 m s" i s the sounding speed t o 100 m d e p t h . The h e a v y l i n e i n d i c a t e s the channel a x i s . 91 1  21  Tailing  22  S i d e - s c a n s o n a r r e c o r d , J u n e 1977. The numbers 1-6 i d e n t i f y t h e axes of t h e s i x c o n s e c u t i v e bends; t h e vertical lines indicate r a d a r f i x e s ; S and B t h e s u r f a c e a n d b o t t o m e c h o e s a n d 0 z e r o r a n g e on each c h a n n e l . The u p p e r h a l f o f e a c h p a n e l i s t h e r e c o r d from the s t a r b o a r d t r a n s d u c e r ; the lower h a l f t h a t f r o m t h e p o r t t r a n s d u c e r . ( S e e a l s o F i g . 29).  92  ( a ) V e s s e l p o s i t i o n s f o r D e c e m b e r , 1977 s u r v e y . Solid triangles are radar fixes; solid circles are adjusted positions, (b) B a t h y m e t r y i n December, 1977. A x i s o f November, 1976 c h a n n e l i s a l s o shown ( d a s h e d l i n e ) .  93  23  t h i c k n e s s i n meters,  12 J a n u a r y ,  24  December 1977 c r o s s - c h a n n e l p r o f i l e s , c h a n n e l , a t l o c a t i o n s i n F i g . 23.  25  Depth o f November, 1976 c h a n n e l of l o n g - c h a n n e l d i s t a n c e .  26  1977.  91  l o o k i n g down-  94  a x i s as a f u n c t i o n 95  Cross-channel p r o f i l e s , l o o k i n g down-channel, i n November 1976. ( a ) u p p e r r e a c h ( b ) m i d d l e r e a c h ( c ) lower reach ( d ) meander reach at channel c r o s s o v e r s . See F i g . 27 f o r l o c a t i o n s .  97  27  Sounding.transects  98  28  S e i s m i c r e f l e c t i o n p r o f i l e s a c r o s s upper r e a c h : (a) A x i a l L i n e 2, 1977; ( b ) A x i a l Line 2, 1975. See F i g . 18, 19 a n d 21 f o r l i n e l o c a t i o n s .  29  for profiles  i n F i g . 26.  (a) Channel axes i n January, 1977 ( s o l i d l i n e ) and November, 1976 ( d a s h e d l i n e ) , (b) C h a n n e l a x e s i n June, 1977 (solid lines) and November, 1976. ( d a s h e d l i n e ) . N o t e o f f s e t o f s i d e s c a n p r o f i l e due t o s h i p t o t o w - f i s h s e p a r a t i o n . (See a l s o F i g . 2 2 ) .  30  Definition s k e t c h of meanders. Based F i g . 1 i n L e o p o l d a n d Wolman ( 1 9 6 0 ) .  31  S e i s m i c p r o f i l e s a c r o s s t h e meander r e a c h , 1977, l o o k i n g d o w n - c h a n n e l .  32  Seismic profiles across t h e a r e a o f t h e 1976-77 l o w e r r e a c h i n 1975, l o o k i n g d o w n - i n l e t .  33  Bathymetry, September c j =1492.8 m s" . 1  1978.  i n p a r t on January  z'=zc '/c , s  5  99  101 102 104 108  where 11 1  XV  34  Bathymetry, February c ' =1 473.2 m s" .  1979.  z'=zc '/c , 3  where  5  111  1  s  35  D e p t h d i f f e r e n c e map, November 1976-September 1978. P o s i t i v e v a l u e s i n d i c a t e net deposition. Negative v a l u e s are shaded.  112  36  Bathymetry, August  115  37  C r o s s - c h a n n e l p r o f i l e s , A u g u s t 1979, l o o k i n g c h a n n e l , (a) and (b) Upper channel; (c) c h a n n e l . See F i g . 37 f o r l o c a t i o n s .  38  Sounding  lines  1979.  corresponding  to p r o f i l e s  3 1 . C h a n n e l s a r e i n d i c a t e d by s o l i d 39 40  41 42  Depth  of c h a n n e l a x i s , August  downLower  116  in Fig.  lines.  117  1979.  118  (a) B a t h y m e t r y o f f H a n k i n P o i n t i n J a n u a r y 1977 and (b) A u g u s t 1979; ( c ) D e p t h d i f f e r e n c e map, H a n k i n P o i n t area: January, 1 9 7 7 - A u g u s t , 1979. ( N o t e c h a n g e i n s c a l e ) . N e g a t i v e v a l u e s a r e s h a d e d and i n d i c a t e e r o s i o n . Redondo c a n y o n a n d f a n - v a l l e y ( a d a p t e d f r o m H a n e r , 1971).  120 125  Hypothetical submarine channel trajectories in slope-discharge space. The broken line i s that separating braided from meandering and straight rivers (Leopold and Wolman, 1960). Meander curvature increases with decreasing slope.  126  43  Comparative s i z e a n a l y s i s : Sedigraph plus sieving.  132  44  Surficial s e d i m e n t s , December 1977. (a) Median diameter (/im). (b) Cu concentration (ppm). (c) Specific gravity. The 1977 channel a x i s is i n d i c a t e d by t h e d a s h e d l i n e .  135  45  Core and g r a b sample  138  46  Sand content (%) F e b r u a r y , 1979.  47  Clay content F e b r u a r y , 1979.  (%)  of  surficial  sediments  in  48  Cu c o n c e n t r a t i o n F e b r u a r y , 1979.  (ppm)  in  surficial  sediments  in  49  Grab sample  50  Sand content 1979.'  Sedigraph  versus  l o c a t i o n s , F e b r u a r y 1979. of  surficial  l o c a t i o n s , August (%)  alone  in  sediments  in  1979.  surficial  sediments,  138 139 139 140  August 141  xvi  51  Cu concentration A u g u s t 1979.  52  Percent sand versus s u r f i c i a l sediments.  53  ( a ) P e r c e n t c l a y and (b) c o n c e n t r a t i o n i n t h e 1979  54  Core  55  Mosaics of some o f t h e h a l f - c o r e s f r o m November, 1976. The s o l i d c i r c l e s on o p p o s i t e s i d e s o f a c o r e i d e n t i f y the location of a splice between two photographic prints. 76-6 i s a quarter-core. D i s t u r b a n c e s due t o s p l i t t i n g a r e p r e s e n t a t 5 cm in 76-3, 33-35 cm and 60-78 cm i n 76-4, a n d 42 cm i n 76-8. S l i g h t b r e a k s i n s a n d l a y e r s o c c u r a t 22, 36 and 61 cm i n 6; 19 and 31 cm i n 7; a n d 2 cm i n 8. E was gouged by material adhering to the splitting wire. Other l a b e l s are d i s c u s s e d i n the text.  149  Core 76-1, showing mosaic of the h a l f - c o r e and s i z e a n d Cu a n a l y s i s r e s u l t s . N o t e t h e light and dark bands : l i g h t b a n d s a r e a t 12-15, 2 8 - 3 8 , 48-52 and 58-60 cm d e p t h . F i n e r l a m i n a e a r e i n e a c h b a n d . The d o w n - t u r n i n g o f t h e l a m i n a e a t t h e e d g e s i s due to f r i c t i o n at the l i n e r w a l l d u r i n g p e n e t r a t i o n .  151  Core 76-2. The dark v e r t i c a l s t r e a k i n t h e upper 20 cm i s i r o n - o x i d e f o r m e d d u r i n g d e w a t e r i n g . The light streaks i n the l o w e r 30 cm were f o r m e d by material adhering to the splitting wire. Note i n c l i n e d l a m i n a e , a n d d i s t u r b a n c e i n u p p e r 10 cm.  152  Core cm.  154  56  57  58 59  (ppm)  in  surficial  Cu c o n c e n t r a t i o n i n t h e  upper  C o r e 76-5, l o w e r h a l f . flame structures at 115 cm.  1976.  61  Lower s e c t i o n o f c o r e 76-6. c o a r s e l a y e r s a t 76 cm.  the  change  Note the  in  76-9.  N o t e Ta  144  (massive,graded)  the  155 157  well-resolved 158  Lower s e c t i o n o f c o r e 76-7. V e r t i c a l s c a l e of bargraph i s twice that of the photograph. h o r i z o n t a l s c a l e s f o r Cu and Fe a r e different this c o r e . Note disturbed basal section, u n c l a s s i f i e d s t r u c t u r e a t 27-28 cm. Core  142  148  Note possible load-casted 100 cm and m u d - b a l l a t 112-  U p p e r p a r t o f c o r e 76-6. N o t e s l o p e o f t h e l a m i n a e a t 54 cm.  63  Fe  141  h a l f . Note d i s t u r b a n c e i n top 8  60  62  1979  percent silt versus s u r f i c i a l sediments. .  l o c a t i o n s a n d b a t h y m e t r y , November  76-5,  sediments,  i n t e r v a l at  the The for and 16-  159  xvi i  34 cm, and p o s s i b l e Tb a n d Td i n t e r v a l s a t 8-16 cm.  (parallel  laminated)  64  C o r e 76-10. N o t e m o t t l e s a n d h o l e s , p a r t i c u l a r l y l o w e r h a l f , and d a r k p r e - m i n e s e d i m e n t a t b a s e .  65  Core 76-11. Note c o p p e r - and i r o n - p o o r d a r k p r e mine sediment e x t e n d i n g t o t h e base of t h e c o r e ( a t 42 cm, n o t s h o w n ) .  163  Cores from F e b r u a r y 1979. Note that darker coloration implies coarser m a t e r i a l except f o r the p r e - m i n e s e d i m e n t s i n d i c a t e d by t h e cross-hatching i n c o r e s 1A-1C.  165  67  Tailing thickness, as derived v e r s u s t i m e a t 1976 c o r e s i t e s .  168  68  P h o t o g r a p h ( l e f t ) and X - r a d i o g r a p h ( r i g h t ) of 1 cm thick slab f r o m c o r e 79-6. Note congruence i n s h a d e s o f g r e y b e t w e e n t h e two p r i n t s , a n d t h e v e r y f i n e laminae i n the X-radiograph.  170  1976 m o o r i n g l o c a t i o n s , p l u s s t a t i o n J ( l o c a t i o n Run 2 f r o m J o h n s o n , 1 9 7 4 ) .  171  66  69 70  f r o m CSP  in  160  surveys,  162  of  C u r r e n t m e t e r r e c o r d s a t 7 6 / 1 , 24-26 A u g u s t 1976. (a) Temperature, s a l i n i t y , p r e s s u r e and p r e d i c t e d tides (dots), direction (-1 80°=down-inlet) and speed. (b) A x i a l (u) a n d c r o s s - i n l e t ( v ) v e l o c i t y c o m p o n e n t s r e l a t i v e t o an u p - i n l e t d i r e c t i o n o f 70° t r u e . Time 0 i s 0 h PDT, 24 A u g u s t 1976.  172  Records from lower meter a t 76/2, with the predicted t i d e . Up-inlet=0°. Time 0 i s 0 h PST, 20 November 1976. The u a n d v c o m p o n e n t s a r e parallel to and t r a n s v e r s e t o t h e i n l e t a x i s , r e s p e c t i v e l y . R e c o r d e d s p e e d i s z e r o f o r most o f t h e record due to r o t o r f o u l i n g (see t e x t ) .  174  72  Record from upper meter a t 76/2. A x i a l (u) a n d t r a n s v e r s e (v) v e l o c i t y components a r e p l o t t e d .  175  73  V e s s e l mooring s t a t i o n s ,  176  74  C u r r e n t meter records at fore-and-aft mooring station 78/2 and p r e d i c t e d t i d e on 14-15 S e p t e m b e r 1978. Arrows- i n d i c a t e 0330 h and 0525 h PST. Note t h e absence of major h i g h - f r e q u e n c y f l u c t u a t i o n s i n the direction records. U p - i n l e t i s 72° t r u e . The p r e s s u r e s e n s o r on t h e BOTTOM m e t e r malfunctioned d u r i n g the f i r s t p a r t of the second c a s t .  71  •75  September  1978.  T r a n s v e r s e ( v ) and a x i a l . ( u ) c o m p o n e n t s of v e l o c i t y a t 78/2 w i t h s h i p m o t i o n , ( b ) , removed. X and Y a r e east-west and north-south d i s p l a c e m e n t s of the  179  xvi i i  180  ship. of s a l i n i t y  and s u s p e n d e d  particulate  76  Contour p l o t s a t 78/2.  77  A x i a l component o f v e l o c i t y a t s t a t i o n J ( F i g . 69) at 1.0-1.5 m f r o m t h e b o t t o m i n J u l y 1973. T i d a l extrema are those predicted for Coal Harbour (adapted from Johnson, 1974).  78  79  80  81  82  83  84  85  86  Schematic representation of component i n t h e d e e p w a t e r a s a p h a s e and r a n g e o f t h e t i d e .  axial function  velocity of the  181  183  1 84  C u r r e n t d i r e c t i o n a n d smoothed s p e e d f r o m a l l t h r e e meters and the p r e d i c t e d tide a t s t a t i o n 78/2, of 72' S e p t e m b e r 14-15 1978. A d i r e c t i o n 1 s upinlet.  187  Axial (u) and transverse (v) components of v e l o c i t y , c o r r e c t e d f o r s h i p m o t i o n , a t each of the t h r e e m e t e r s a t 7 8 / 2 , on 14-15 S e p t e m b e r 1978.  188  Sonograph of t h e c h a n n e l and discharge plume, l o o k i n g u p s t r e a m , d u r i n g f l o o d t i d e 3.5 h a f t e r low water, 22 November 1976, 1050 h PST. S = s i d e - e c h o , P=plume. V e r t i c a l l i n e s i n d i c a t e t i m e s o f position fixes taken at 1 min i n t e r v a l s . See F i g . 83 f o r line location.  1 93  the upper F a c s i m i l e r e c o r d s s h o w i n g t h e plume i n 1976. From top reach a t d i f f e r e n t t i m e s , November before low t o b o t t o m , t h e r u n s were made a t 1 h water, 2 h a f t e r LW, 3.5 h a f t e r HW and a t LW. The Fine Line amplifier was switched o f f and t h e Trisponder beacons were n o t i n place d u r i n g the bottom r u n .  194  corresponding to the Locations of transects sonographs shown i n F i g , 81 ( l i n e 78) and F i g . 82 ( l i n e s 24, 48 and 5 4 ) .  1 95  (a) F a c s i m i l e r e c o r d s s h o w i n g t h e plume w i t h i n and spilling from t h e c h a n n e l a t i n c r e a s i n g d i s t a n c e s f r o m t h e o u t f a l l , 22 November 1976. The t i m e s of the p r o f i l e s f r o m t o p t o b o t t o m a r e 1050, 1100 and 1110 h PST (b) P r o f i l e l o c a t i o n s . The profiles in F i g . 85 and i n t h e f r o n t i s p i e c e were o b t a i n e d a l o n g l i n e s 67 and TT'.  1 96  Profile l o o k i n g d o w n - c h a n n e l a t l i n e 67 a t 2124 PST on 21 November 1976, s h o w i n g m a t e r i a l a g a i n s t t h e r i g h t bank.  197  ( F i g . 84b) suspended  (a) Profiles paralleling t h e upper r e a c h a x i s a t 1935 ( l i n e 58) a n d 1944 ( l i n e 59) PST on November  xix  1976. 87  88  89  90  91  92 93 94  95  96  (b) P r o f i l e  locations.  198  Temperature, salinity and total suspended p a r t i c u l a t e (TSP) p r o f i l e s f r o m the plume during t h e a p r o n r e g i m e a t 78/2, S e p t e m b e r 1978.  200  Sonographs c o r r e s p o n d i n g to p r o f i l e s i n F i g . 87, showing the near-bottom turbid zone and the sampling b o t t l e s descending into and remaining s u s p e n d e d w i t h i n i t . The bottom echo (B) and a false echo (F) arising from interference with another sounder are i n d i c a t e d .  201  ( a ) , (b) and ( c ) P r o f i l e s t a k e n i n S e p t e m b e r 1979 during the r e c h a n n e l i z e d regime. Note the 'cloud' r i s i n g o u t of t h e c h a n n e l . D e p t h s i n m. (d) P r o f i l e locations.  202  S o n o g r a p h s of t h e 25 A u g u s t , 1976 t u r b i d i t y c u r r e n t a t (a) 200 kHz (b) 107 kHz and ( c ) 42.5 kHz. All sounders set at 0.1 ms pulse l e n g t h and 5°xl0° beamwidth. Note paper take-up problem w i t h the 200 kHz recorder ( A ) , and i n t e r f e r e n c e (F) among t h e s o u n d e r s . Compare w i t h f r o n t i s p i e c e and see Fig. 84b f o r t r a n s e c t l o c a t i o n .  205  Surge at 2344 h PST on 12 S e p t e m b e r 1978. (a) 200 kHz (b) 107 kHz. P u l s e l e n g t h s = 0 . 5 ms. Backscatter f r o m t h e d i s c h a r g e plume and l a r g e - a m p l i t u d e m o b i l e scatterers are also evident. Slanting l i n e s at 200 kHz (S) a r e 60 Hz i n t e r f e r e n c e .  207  S u r g e a t 0225 h PST kHz (b) 107 kHz.  208  on  Surge at 0525 h PST kHz (b) 107 kHz.  13 S e p t e m b e r on  1978.  15 S e p t e m b e r  1979.  (a) (a)  200 200 209  Two t y p e s of t u r b i d i t y s u r g e : s l u g ( s o l i d l i n e ) and c o n t i n u o u s s o u r c e ( d a s h e d l i n e , a d a p t e d f r o m Komar, 1977).  210  R e c o r d f r o m t h e 11 kHz p i n g e r , 15 S e p t e m b e r , 1978. A= d i r e c t pulse, B= b o t t o m - r e f l e c t e d pulse, C= p u l s e s r e f l e c t e d by c u r r e n t m e t e r s and weight (W).  211  Contour plot of digitally processed 200 kHz r e v e r b e r a t i o n f r o m t h e s u r g e a t 0225 h PST on 13 September 1978. ( A l s o see F i g . 9 2 ) . E a c h p o i n t i n the contour g r i d i s the average of 10 samples vertically (0.2 ms) and of 10 consecutive t r a n s m i s s i o n s (5 s) horizontally. Note that the 1.0-2.0 v o l t i n t e r v a l i s cross-hatched normally to t h e c r o s s - h a t c h i n g i n t h e 0.5-1.0 v o l t i n t e r v a l .  213  XX  97  V e r t i c a l p r o f i l e s of the s i g n a l b a c k s c a t t e r e d from the s u r g e i n F i g s . 92 and 96. P u l s e l e n g t h = 0 . 5 ms. No a v e r a g i n g of t h e s i g n a l . A z e r o volt reference is plotted at the beginning and end of each profile.  214  T i d a l l y i n d u c e d change i n the a c o u s t i c b a c k s c a t t e r at 200 kHz at 78/2 a t 0330 h PST, S e p t e m b e r 15, 1978. D e p t h s i n fm; 0=50, 20=60 fm.  217  99  Tidally 78/1.  induced  219  100  Current 1978.  meter  101  S h i p m o t i o n a t 78/1 on Y are east-west and the s h i p .  98  change i n a c o u s t i c  backscatter  records .  15-16  a t 78/1  on  at  September  15-16 S e p t e m b e r 1978. X and n o r t h - s o u t h d i s p l a c e m e n t s of  A r e a c o v e r e d by t a i l i n g d i f f e r e n t CSP s u r v e y s .  103  Schematic diagram of a d e n s i t y s u r g e , (a) on a h o r i z o n t a l b o t t o m , (b) on a s l o p i n g b o t t o m . Except for the velocity profile at x , for which v e l o c i t i e s a r e r e l a t i v e t o t h e bed, v e l o c i t i e s and c o o r d i n a t e s are r e l a t i v e to the nose.  227  Plots of 2 C„ versus bottom slope using M i d d l e t o n ' s (1966b) r e s u l t s . T h o s e o f S h w a r t z e t a l ( 1 9 7 3 ) a r e shown by s o l i d l i n e s , ( a : s a l i n e slugs; b: t u r b i d i t y s l u g s ) .  229  105  Combination bottle.  275  106  UBC 5 m launch: outboard engine.  107  ( a ) T r a n s d u c e r f a i r i n g and 19.6 cm d i a m e t e r 192 kHz transducer (solid dark circle). (b) Transducer fairing while under way. W i n c h e x h a u s t p i p e a l s o evident.  278  108  November, 1976  279  109  ( a ) and  (b) S e p t e m b e r ,  110  (a) and  (b) F e b r u a r y ,  111  August,  1979  •112  given  thickness  for  221  102  104  of a  220  224  1 / 2  250  ml  suspended s o l i d s  sampler  and  NIO  fibreglas construction, inboard-  ship positions. 1978 1979  ship positions. ship positions.  ship positions.  (a) 50 ml mixing cell used with core samples showing stainless steel outlet at t h e b a s e (b) 50 ml c e l l used in mixing test showing rubber  277  280 281 282  xxi  stopper 113  (A) and s t a i n l e s s  steel outlet  tube  (B).  284  Mixing c e l l test results, showing s e d i m e n t a t i o n diameter distributions taken at the heights indicated ( i n cm) above t h e bottom of t h e c e l l . N o t e t h a t 2 r u n s were, made a t e a c h h e i g h t .  286  Typical grab sample distributions showing bimodality at the split point (0.0625 mm). F r e q u e n c y h i s t o g r a m s and c u m u l a t i v e p e r c e n t c o a r s e r c u r v e s , one a g a i n s t a linear scale (+), another against a normally d i s t r i b u t e d p r o b a b i l i t y scale ( A ) , are p l o t t e d .  287  115  Bathymetry locations.  296  116  Monthly chlorophyll d e p t h a t s t a t i o n A.  117  Average c o u n t s of d i s c - s h a p e d diatoms on filters from samples at stations 1-4. The error bars r e p r e s e n t t h e s t a n d a r d d e v i a t i o n f r o m t h e mean: ( a ) 13 b o t t l e c a s t s ( b ) 5 c a s t s ( c ) 8 a n d (d) 2.  302  118  F e b r u a r y 1979 c o r e l o c a t i o n s and b a t h y m e t r y .  304  119  Diatom  306  120  ( a ) W a t e r d e p t h a t c o r e s i t e 79-6 a n d t h i c k n e s s of t h e t a i l i n g d e p o s i t a t s i t e 79-6 a n d 7 9 - 1 1 , (b) and (c), versus time.  311  121  1976  312  122  Diatom  123  T h i c k n e s s of the t a i l i n g versus time.  124  A x i a l (u) and c r o s s - i n l e t ( v ) v e l o c i t y components with s h i p m o t i o n ( F i g . 101) r e m o v e d , a s r e g i s t e r e d by t h e t o p ( a ) , m i d d l e (b) and b o t t o m ( c ) m e t e r s a t 78/1 on 15-16 S e p t e m b e r , 1978.  316  125  Records from the t o p meter S e p t e m b e r , 1978.  318  126  Records from the m i d d l e meter 17-18 S e p t e m b e r , 1978.  127  Records from the bottom meter 17-18 S e p t e m b e r , 1978.  128  Axial with  114  in  September  1978  showing  a levels  station  (1971-1978) from 5 m  r e c o r d s f r o m c o r e s 79-6  and  79-11.  c o r e s i t e s and b a t h y m e t r y . p r o f i l e s o f c o r e 76-4.  296  313  deposit at core s i t e  at station at  78/3  station at s t a t i o n  on  76-4  17-18  78/3 78/3  on on  (u) and c r o s s - i n l e t ( v ) v e l o c i t y components, s h i p m o t i o n ( F i g . 129) r e m o v e d , f r o m t h e t o p  314  319 320  xxi i  ( a ) , m i d d l e (b) and b o t t o m 17-19 S e p t e m b e r , 1978. 129  (c) meters  at  78/3  on  321  Ship motion at 78/3. X and Y a r e t h e n o r t h - s o u t h and e a s t - w e s t c o m p o n e n t s o f d i s p l a c e m e n t ; u and v a r e t h e c o r r e s p o n d i n g a x i a l and t r a n s v e r s e v e l o c i t y components.  322  130  R e c o r d s f r o m t h e t o p ( a ) , m i d d l e (b) and m e t e r s a t 78/4 on 19-20 S e p t e m b e r , 1978.  324  131  Axial (u) and c r o s s - i n l e t ( v ) v e l o c i t y c o m p o n e n t s a t 78/4 c o r r e c t e d f o r s h i p m o t i o n ( F i g . 1 3 2 ) .  325  S h i p m o t i o n a t 78/4. X and Y are the north-south and east-west c o m p o n e n t s o f d i s p l a c e m e n t ; u and v a r e t h e c o r r e s p o n d i n g a x i a l and t r a n s v e r s e v e l o c i t y components.  326  132  bottom  (c)  xxi ii  ACKNOWLEDGMENTS I w i s h t o e x p r e s s my contributed my  t o t h e c o m p l e t i o n o f t h i s t h e s i s , and  s u p e r v i s o r s , D r . R. W.  their  direction  and  L e B l o n d , D r . A. G. and  support;  Dr.  J.  W.  vessels;  P. D.  Geological  Macdonald,  H.  Sjoholm Hole  S. Pond f o r  their  Dr.  S.  assistance.  Dr.  guidance  rebuilt  J . de  P. S t o r m ,  and  the t e c h n i c a l  S c i e n c e s who  the staff  And  recovery.  Sullivan  the and  current  P. D.  digitizing  Kamitakahara  the  analog  meter  wrote  are  also  or  due  Hodge  Hydrographic equipment);  current  meters  Service D r . C.  Department of C i v i l  H.  P.  technical and  procedures.  deployment  and size  the diatoms.  and  drafted  software  D. for  translating most  of  the  t o t h e i n d i v i d u a l s and o r g a n i z a t i o n s  and  M.  Farmer  mooring  (side-scan Pharo  Reimer,  manuscript.  g e n e r o u s l y l o a n e d e q u i p m e n t : D r . D.  equipment,  D.  facilities  modified  recordings  A a n d e r a a r e c o r d s , r e s p e c t i v e l y . G.  Thanks  R.  Reimer a s s i s t e d w i t h the  acoustic  f i g u r e s . J . H e l l o u typed the  these  Heckl,  filtration  a n a l y s e s . Rosemary W a t e r s i d e n t i f i e d and c o u n t e d L a p l a n t e and G.  (CSS  of t h e D e p a r t m e n t  E. V. G r i l l p r o v i d e d l a b o r a t o r y  supervised  M.  of  Breymann f o r  f o r t h e t r a c e m e t a l a n a l y s e s and  Stickland  crews  t h e l a u n c h ; H.  A. Von  H.  Capt. J .  Wheeler  M o r a , A. R a m n a r i n e , P. D.  and M.  for,  discussions  (CSS V e c t o r ) , C a p t . M.  ( W a l t e r M.)  R e i m e r and  S t o d d a r t , M.  who  Murray,  to  t o D r . S. E. C a l v e r t , D r . P.  L e w i s and D r .  and C a p t . K.  R i c h a r d s o n ) , Mr.  A.  B u r l i n g and  who  especially  c r i t i c i s m of t h i s m a n u s c r i p t . I a l s o w i s h t o thank  Marsten  of  g r a t i t u d e t o t h e many i n d i v i d u a l s  E n g i n e e r i n g , U.  components);  sonar  ( S e d i g r a p h and B. C.  (positioning  and  Canadian  positioning  gravity-coring gear); (surveying equipment),  xxiv  Dr.  P.  J . Harrison  S. Pond ( e l e c t r o n i c  (Coulter  C o u n t e r ) ; D r . T. R. O s b o r n  equipment).  I am g r a t e f u l t o I s l a n d Hillis  and  cooperation  C.  I  was  Pelletier  i n making  Mac I , a v a i l a b l e  Copper in  Mine  to  b o t h d a t a and  Strategic Murray  Grant  for  facilities,  i t s staff., their  R.  generous  including  the  MacMillan Family Scholarship  from  t o me.  supported  Dr.  and  particular,  by  a  1977-1979 a n d NRC G r a n t A5374 t o D r . R.W. A3542  and D r .  J.W.  Murray.  The  project  (Group) G0208 t o D r . R.W.  i n November 1978.  Burling  and NRC  Grant  was f u n d e d by NSERC  Burling  and  Dr.  J.W.  1  CHAPTER _1_ INTRODUCTION This  thesis  submarine  concerns  channel  the  systems  formation  as  a  was  Copper  that  the  sediment  from  Mine.  The  their  direct  i n t o Rupert  quasi-steady  release  a submerged p o i n t real  mark i n t h e g e o l o g i c  of  large  longstanding  by  project  quantities  s o u r c e a f f o r d e d an  of  opportunity  time - processes  which  have  r e c o r d but f o r which almost  no  currents interest  have  represented  of  in  oceanography  formation  of  slope. This submarine canyons  submarine hypothesis  f a n s and are  canyons is  now  in  to  the  evidence i s l a r g e l y  measure  on  deep sea  inferential,  l a i d down by 1 9 5 0 ) . The  identified  In  the  shelf  and  and  the  accepted,  from t h e mouths of t h e  has  been  t o have  transported  (Horn e t a l , 1971). and  i s based  in  The  large  t h e a s s u m p t i o n t h a t t u r b i d i t e s - d e p o s i t s w i t h more  or l e s s w e l l d e f i n e d c h a r a c t e r i s t i c s  paleobasin  (1936)  for  a l s o a s c r i b e d t o t h e s e f l o w s , which appear  existing  Migliorini,  responsible  generally  fan-channels emanating  continents  material  problem  the c o n t i n e n t a l  been t h e p r i m a r y m e c h a n i s m by w h i c h s a n d the  a  ever since Daly  p r o p o s e d t h a t t h e y were t h e e r o s i v e a g e n t  be  Inlet  observations exist.  Turbidity  from  of  currents  hypothesis i n undertaking the  to study these processes i n left  evolution  r e s u l t of t u r b i d i t y  g e n e r a t e d by t h e d i s c h a r g e o f m i n e t a i l i n g Island  and  has  individual  (Bouma,  turbidity  1962)  currents  r e l a t i v e ease w i t h which  led  to their  - represent (Kuenen  turbidites  p l a y i n g a fundamental  and can  role in  analysis.  spite  of  the  general  success  which  the  turbidity  2  current-turbidite geologic which  m o d e l has  in  rather  Keulegan, only  1957  currents  has  i n the  even  1929  in  laboratory  cases  "...our understanding  tempered has  by  In  the  was  'witnessed'  length  although  stages  t h e assumed c u r r e n t was  reproduced Chapter  frequency i n the  7.  The  one  or  actual  study, sonar.  those  full  scale  r e s p o n s i b l e f o r the record. the  Cores  The  orders  as b e i n g has of  are  below  surge  those  from the  the event  are  tests,  which  are  and  fan  in  question  of medium s c a l e . been  considered  i s q u i t e obvious  levees contain deposits  features characteristic  of  discussed  laboratory  generally  levees,  current  sonographs  l a r g e r submarine canyons  which  formation  a turbidity  in  the deep ocean. Perhaps t h e n ,  Channel o v e r s p i l l ,  h a v e some o f  the  l e n g t h s c a l e s , of the  two  i s most a p p r o p r i a t e l y r e g a r d e d  acoustic  of  considerations  f r o n t i s p i e c e , and  of m a g n i t u d e a b o v e  probably  in  theoretical  of the p r e s e n t  e x p e c t e d t o have p r o d u c e d the valleys  not  (1978a),  t o d e s c r i b e an  using high  in  several orders  Heezen,  current."  early  t h i s event are  the  e m p i r i c a l c o n s t r a i n t s - so f a r , t h e r e  been no w i t n e s s  turbidity  at  few  (e.g.  of the a c t u a l mechanism  i s b a s e d l a r g e l y on  The  turbidity  b r e a k s s u c h as  Grand Banks e a r t h q u a k e  these  (e.g.  1967).  surge-type  submarine c a b l e  in  other  experiments  of  the  instances  1966b, 1966c a n d  o b s e r v e d d i r e c t l y . To q u o t e Normark  process  i f any,  by a c t u a l o b s e r v a t i o n ,  Middleton,  through  i n t e r p r e t a t i o n of  few,  real-time observations been  and  scale  1958;  f o l l o w i n g the  1963),  had  been v e r i f i e d  small and  successive  series  has  r e c o r d , t h e r e h a v e been v e r y  the  than  model  of  turbidites.  in  the  which To  my  3  knowledge,  this  channelized  turbidity  the  levees  itself,  of s o l i d s .  risk  controlled  of a  of  turbidites  be  used t o o b t a i n  can  in  of t u r b i d i t y  which subject  damage  environment  the dynamics of t h e  and  and  like  i_n s i t u  burial.  Rupert  c o u l d be o b t a i n e d  In  not only  the r e s u l t i n g deposit  the  s u i t e d to the instrumentation  a  Inlet,  surge f l o w s , but a l s o t o r e l a t e  confining channel.  potentially  Such systems a r e i d e a l l y  surges,  of  that observations  of  systems  of t h e parameters governing  of t u r b i d i t y  severe  sensing,  i n c l u d i n g the flow thickness  concentration  to  the observation  surge and t h e p r e s e n c e  remote  direct estimates  study  of r e s u l t s -  - i s unprecedented.  Acoustic  flow  combination  more  or  less  the i m p l i c a t i o n i s to test  the  theory  the c h a r a c t e r i s t i c s  t o t h e s c a l e s of t h e m o t i o n and of i t s  The t h e s i s r e p r e s e n t s  a first  step  in  this  direction. The  use  of  acoustic  backscattering  techniques  f o rthe sediment  purpose of d e t e c t i n g t u r b i d i t y  c u r r e n t s and  suspended  is  The  indicate that  central  appropriate  to  application  study.  circumstances  concentration backscattered  this  of  results  i t is  suspended  possible  matter  from  s i g n a l . T h i s a p p e a r s t o be of  the  method  with  previous research sensing, The  remainder of t h i s chapter work i n R u p e r t  Inlet.  the  respect  second chapter  Detailed  of the  successful  to the q u a n t i t a t i v e environment.  reviews  the  of  previous  such as a c o u s t i c  i n the appropriate reviews  first  the  i s concerned w i t h a review of  i n f i e l d s of s p e c i a l i n t e r e s t , are presented  obtain  the amplitude  d e t e c t i o n of suspended sediment i n a marine The  to  under  theory  remote  chapters. of  scattering  and  4  a t t e n u a t i o n of a p l a n e the  circumference  i n c i d e n t wave. determination absorption and  in  s o u n d wave by  A  new  of  the  result  I n C h a p t e r 3,  the  signal  Chapter  4  disappearance  its of  pronounced  and  matter  e i t h e r do  not  t h e e v o l u t i o n of t h e  initial  and  or are to  surficial work was  Chapter and  5,  sediments  the  i n order  within  of  in  obtain  suspended of  the  the  tailing is  shown  tailing  rechannelized  final  channel,  through  which  of  'the  phase.  exhibited  characteristics  s u b m a r i n e c h a n n e l s and  and  deposit  of s u b a e r i a l  material  losses  deposition - processes  which  limited  and  are  importance i n  considerable  rivers  i n f l u e n c e on  not the  channels.  w i t h i n the  conducted  to  to the  exercise  m o r p h o l o g y of s u b m a r i n e In  used  state,  i t s morphological  overspill  f l o o d - appear  considerably  channelized  initial  of o t h e r  occur  a  observed backscatter  beds. E n t r a i n m e n t of o v e r l y i n g f l u i d , channel  interface,  theory.  meanders,  through  the  the  upon t h e  compared w i t h those  viscous  Observations  suspended  the channel  Emphasis i s p l a c e d  in  and  and  the  attenuation.  sounding.  describes  morphology from  interest permits  the  allows  solid-fluid  t o the d e t e c t i o n of c l o u d s  are presented,  be c o n s i s t e n t w i t h  which  r e s u l t s of C h a p t e r 2 a r e  acoustic  backscattered  river  of the  appropriate  using  discharge  obtained  l e n g t h of  r e l a t i v e magnitude of t h e r m a l  simplified calculation  to  is  i n the boundary l a y e r s a t the  expressions  spherical particle,  of w h i c h i s much l e s s t h a n t h e  many c a s e s of p r a c t i c a l  sediment  a solid  and  properties  of  the  sediment column - a r e to c h a r a c t e r i z e beyond  the  the  leveed  sediments - both presented. properties channel,  and  This of to  5  identify  turbidites  c o p p e r and i r o n mass  is  sediment  rate.  explored.  The l a t t e r  accumulated  reflection  tailing  profiles,  number  of  from  the  presented tidal  and  forcing.  Johnson  6,  results  analysed  and  with  and  from  seasonal  a  the  i n depth seismic  changes  i n the  in" the c o r e s .  current  measurements  with  descriptive  response t o  measurements  model  are  presented  by by  ( 1 9 7 3 ) . Some r e f i n e m e n t s t o t h i s m o d e l a r e s u g g e s t e d . surge flows a r e present  in  some  the records. In  Chapter  turbidity of  turbidites  i n terms of the deep-water  P e r t u r b a t i o n s due t o t u r b i d i t y of  of  of  current recurrence  inferred  These d a t a a r e c o n s i s t e n t  (1974)  Drinkwater  the  use  large-scale  was o b t a i n e d f r o m c h a n g e s  t h i c k n e s s as  and  The  down by  The t u r b i d i t y  c o n c e n t r a t i o n of large diatom f r u s t u l e s In C h a p t e r  column.  for deposits l a i d  i s e s t i m a t e d from t h e  deposition and/or  the  as t r a c e r s  movements  interval  within  the  7,  current  sonographs  of  the  discharge  surges a r e presented,- and used t o  properties  of  t h e s e f l o w s , and t h e i r  plume infer  and some  i n f l u e n c e on t h e  f o r m a t i o n of submarine c h a n n e l s . I n C h a p t e r 8, a s i m p l i f i e d turbidity  flow  i n the submarine  an e a r l i e r m o d e l by Komar ( 1 9 6 9 ) ambient  water a t t h e upper  sediment  transport  consistent  analytical  with  seismic r e f l e c t i o n  model  of  continuous  c h a n n e l i s d e v e l o p e d , b a s e d on but  boundary.  including  entrainment  T h i s model y i e l d s  relative  r a t e s b y c o n t i n u o u s and s u r g e f l o w which those o b t a i n e d from a sediment s u r v e y s and from g r a v i t y  budget  cores.  of  are  b a s e d on  6  1.1 The M i n i n g  Operation  I s l a n d Copper Mine 1971.  The  tailing  sea  water  depth and  the  as a s l u r r y  ratio  r a t e i s 1.4 m  1:4:5  of  solids,  parts  by  s " . The s e a  3  1  above  bottom  water  freshwater  and  v o l u m e . The v o l u m e is  drawn  ( o u t f a l l , F i g . 1). In October  d i s c h a r g e p i p e was l a i d ,  but the o u t f a l l  old discharge line  is  replacement.  tailing  The  still  used  from  a  is  froth-flotation.  a median d i a m e t e r The  0.3%,  maintenance  t h a t p a r t of t h e host  the t a i l i n g  o f 0.030 mm a n d 6 5 - 7 5 % a r e s m a l l e r t h a n  the  cutoff  i s i n t h e 80-90% r a n g e .  i s dumped i n t o t h e i n l e t  dump ( F i g . 1) a t a r a t e a p p r o x i m a t e l y of t h e t a i l i n g .  have 0.074  grade i s Rock  of  a t t h e waste  three to four  F u r t h e r d e t a i l s may be f o u n d  which  particles  g r a d e o f t h e o r e body i s 0.52% Cu, t h e c u t o f f  below  on i t s  rock  ore-bearing  The p a r t i c l e s c o n s t i t u t i n g  and e x t r a c t i o n e f f i c i e n c y  grades  1975 a new  p o i n t was t h e same. The  during  remains a f t e r m i l l i n g and removal o f t h e  mm.  from a  o f 1 5 m , a n d t h e d i s c h a r g e p o i n t i s 49 m b e l o w t h e s u r f a c e 1 m  by  October 1  1.07 m i n d i a m e t e r  discharge  disposal in  i s d i s c h a r g e d a t a r a t e o f 380 .kg s~  pipe  in  (ICM) began t a i l i n g  times  that  i n E v a n s and P o l i n g  (1975) a n d P o l i n g (1979) . As an and  part  of the requirements  extensive environmental  In  particular,  s t a t i o n s h a s been v e r y exchange p r o c e s s  the  make  considerable  use  t i m e - s e r i e s of monthly  useful  outlined  ICM m a i n t a i n s  m o n i t o r i n g p r o g r a m . The p r e s e n t  o t h e r s h a v e been a b l e t o  data.  f o r i t s permit,  in  studies  i n the next  of  section.  the  of  study these  hydrographic deep-water  8  1.2 P r e v i o u s Work i n R u p e r t 1.2.1  Physical  Inlet  Oceanography  Rupert I n l e t and H o l b e r g I n l e t (Fig.  Ocean  passage Coast,  v i a Quatsino  reach  3 m s"  the  Narrows.  discharge  compared t o  from  an  (Drinkwater,  in this  British  Columbia  i s a t a d e p t h o f 18 m a t t h e n o r t h e r n e n d  operations the  Marble  average  itself  Pickard  tidal  i n t h e H a n k i n P o i n t a r e a was  began.  The  River  (140 m  inflow  of  major 3  s"  7.8  1  x  freshwater on a v e r a g e ) , 10  in  oxygen  a t depth  the  of  the  (>3 ml l " ) .  This  1  combination  inlets,  of  m i x i n g and deep-water  c o n d u c t e d by D r i n k w a t e r a n d O s b o r n and  Stucchi  (1980,  s e a s o n a l l y . Temperature change  by  exchange  process  freshwater  runoff  4-5 °C  1  density  sill  (1975),  1981).  studies  p r o c e s s e s have been Stucchi  and  Farmer  Deep-water exchange  occurs  i n t h e deepest p a r t of  a n d a maximum i n A u g u s t - S e p t e m b e r . to  be  controlled  primarily  from t h e M a r b l e R i v e r which peaks  depth  is  the  a n d 3-4 p p t a n n u a l l y , e a c h r e a c h i n g a  appears  autumn f o l l o w i n g heavy at  1  and l e d t o t h e c o n c l u s i o n  exchange  and s a l i n i t y  minimum i n J a n u a r y - M a r c h  waters  s~  s" .  3  features  i n t e n s e v e r t i c a l m i x i n g had t a k e n p l a c e . Subsequent the t i d a l  3  v e r t i c a l and t h e h i g h c o n c e n t r a t i o n of d i s s o l v e d  u n u s u a l among B r i t i s h C o l u m b i a  basin  m  3  i s 10 km l o n g a n d 1.8 km w i d e .  (1963) n o t e d t h e n e a r h o m o g e n e i t y  field  (1976)  tidal  1973) a n d t h e s l u r r y d i s c h a r g e r a t e o f 1.4 m  Rupert I n l e t  that  Currents  Directions,  The maximum d e p t h  mining  is  Narrows.  (Sailing  1  1 9 7 6 ) . The s i l l  172 m b e f o r e  of  basin  1 ) , w h i c h i s c o n n e c t e d t o Q u a t s i n o Sound a n d t h e n c e t o t h e  Pacific  of  t o g e t h e r form a s i n g l e  rainfall.  S e a s o n a l changes  i n the  The by late  i n the oceanic  may a l s o p l a y a r o l e . D u r i n g p e r i o d s o f  9  high  runoff,  induced  by  Narrows  the  during  depth. This during  vertical  turbulent  jet  diffusion  streaming  flood tide,  i s the s a l t  which the t i d a l  into  resulting  the  e x t r a c t i o n phase  during  water  at  the  the  s p r i n g and  and  (1980,  buoyant  i n 2-3  estimate  of  outside  buoyant  in  t h i s phase. T h i s  the  salinity  1973). the  runoff  while in  Stucchi  basin  is similar  weeks made by D r i n k w a t e r and O s b o r n  to respond to i n c r e a s e d  and  concentration  t h a t 63% o f t h e w a t e r  the  throughout  i n c r e a s e on a v e r a g e ,  (Drinkwater,  to  than the jet  It persists  o f t h e low  the s i l l  weeks d u r i n g  1-4  the deep water  1.2.2  with respect  which p e r i o d  deep water  d e c r e a s e s because  estimates  exchanged  extraction  the  cycle,  the water e n t e r i n g  negatively  replacement phase.  of  water  1981)  a  summer m o n t h s , d u r i n g  temperature  dense  generating salt  d i s s o l v e d oxygen the  of the water a t  of t h e exchange  jet is positively  is  from Q u a t s i n o  f l o o d t i d e e v e n t u a l l y becomes more d e n s e  depth,  initiating  freshwater  basin  in dilution  t h e d e e p water.- As t h e r u n o f f d i m i n i s h e s , basin  of  is  to the  (1975) f o r  during  the  salt  phase.  Sediments Johnson  regime  (1974)  i n the i n l e t  conducted during  the  a  study  period  a f t e r commencement o f m i n i n g o p e r a t i o n s . distributions  in  surficial  of  the  sedimentation  immediately  before  B a s e d on t h e  sediments,  grain-size  seismic  reflection  p r o f i l e s and n e a r - b o t t o m c u r r e n t m e a s u r e m e n t s , J o h n s o n t h a t m a t e r i a l eroded from the bottom during periods  of deep-water  R u p e r t I n l e t and d e p o s i t e d b a s i n , as p a r t i a l l y  i n the  r e p l a c e m e n t was  on t h e s l o p e  Hankin  and  concluded  Point  area  c a r r i e d headward i n  on t h e n o r t h  s i d e of the  i n d i c a t e d by t h e d e c r e a s e i n g r a i n s i z e  with  10  distance  from  Hankin  Point.  Of p a r t i c u l a r  importance t o t h i s  argument and t o t h e p r e s e n t s t u d y i s h i s o b s e r v a t i o n t h a t of  the  7 s u c c e s s f u l meter  up-inlet velocities  deployments  exceeded  maximum  i n Rupert  down-inlet  Inlet,  on  4  maximum  velocities  at  d e p t h s f r o m 79-157 m. In  1979  channel  was  reflection  a n d p o s s i b l y a s e a r l y a s 1973, a l e v e e d found  in  surveys  the  tailing  conducted  annually  G e o l o g i c a l S c i e n c e s a t UBC. A s t u d y levee  slopes  by D a v i s ( 1 9 7 8 )  1.2.3  such as t h a t  of  by  during the  the  seismic  Department  stability  of  of the  f o u n d t h e l e v e e s t o be m a r g i n a l l y  s t a b l e , and p r o b a b l y not s u b j e c t loading  deposit  submarine  to  liquefaction  under  shock  from t h e d a i l y p i t b l a s t .  E n v i r o n m e n t a l Impact S t u d i e s A v a r i e t y o f i m p a c t s t u d i e s h a v e been made s i n c e t h e m i n i n g  operation  began.  Waldichuk  Many  and Buchanan  of  these  a r e o u t l i n e d a n d r e v i e w e d by  ( 1 9 8 0 ) . Somewhat c o n f l i c t i n g v i e w s o f t h e  s i t u a t i o n a r e p r e s e n t e d by G o y e t t e a n d N e l s o n  (1977)  and  Evans  (1978). A  m o n i t o r i n g g r o u p was s e t up a t t h e U n i v e r s i t y  Columbia the  under  Dept.  t h e d i r e c t i o n of P r o f . J.B. Evans,  of  in  Control  Program.  outfall  trace  collected  s e v e r a l r e p o r t s submitted t o the group, which  were  exchange  sediment  of  was  (Hay, M a c D o n a l d a n d M u r r a y , on metal  (Hay, 1978b).  The  head  author  c o n c e r n e d w i t h t h e e x t e n t and morphology  water  then  Mineral E n g i n e e r i n g , to review the data  by t h e m i n e ' s E n v i r o n m e n t a l involved  of B r i t i s h  of t h e t a i l i n g  deposit  1976 a n d .1978), t h e e f f e c t s o f d e e p -  turbidity  (Hay,  concentrations  1978a) a n d t h e c h a n g e s i n with  distance  from  the  11  CHAPTER 2 SOUND SCATTERING AND  ATTENUATION IN SUSPENSIONS  . Fundamentally, the problem suspended  matter  backscattering amplitude  the  reduces  ocean  to  near  obtaining  the  reduction  in  considered  here  viscosity.  The  total  of  from  scattered  are  the  use o f  loss  for  the  particle.  mechanisms  which  purpose  incident  of  The  to present  theoretical  wave  loss  thermal  of t h i s p r e s e n t a t i o n  work and  previous  the  and  in a  mechanisms  diffusion  and  i s both to review  some  new  results.  A  t r e a t m e n t s of the problem  is  i n Table I.  expressions  studies,  f o r t h e wave s c a t t e r e d  to  have  from a s i n g l e p a r t i c l e  which  i n c l u d e t h e e f f e c t s of t h e v i s c o u s and Although  Morse  and  Ingard  (1968,  i t i s useful  thermal loss p.435)  sphere  results  suitable  solid  appeared  i n t h e l i t e r a t u r e and a r e d e v e l o p e d h e r e .  solution  for  suspended  in  scatterers  of  Morse  and  expressions  gas,  (1972)  by e x p r e s s i n g t h e a m p l i t u d e s o f t h e p a r t i a l  the long-wavelength l i m i t ,  a  derived  such  equivalent  i n f l u i d m e d i a have  p r e s e n t e d by A l l e g r a and H a w l e y  o f t h e p h a s e a n g l e s u s e d by F a r a n  mechanisms.  have  expressions for a f l u i d  those  of  acoustic  expression  energy.  result  For a c o u s t i c b a c k s c a t t e r i n g  terms  clouds  s u r f a c e of t h e s c a t t e r e r and w h i c h r e s u l t  the r e l e v a n t e a r l i e r  given  the  an  a r e a f f e c t e d by e n e r g y  b o t h t h e a b s o r p t i o n of energy  summary  through  dilute  and p h a s e o f t h e wave s c a t t e r e d by a s i n g l e  These p a r a m e t e r s operate  in  of d e t e c t i n g  The  not  general  i s reformulated  scattered  waves  (1951). S p e c i a l i z i n g equivalent  in  form  in to to  I n g a r d ( 1 9 6 8 , p . 4 3 5 ) a r e o b t a i n e d , and- t h e  r a t i o of t h e r m a l t o v i s c o u s a b s o r p t i o n emerges i n  a  relatively  12  simple  form.  approach. results  This r a t i o i s the p r i n c i p a l r e s u l t  I t i s found t o agree of A l l e g r a  of the p r e s e n t  favourably with the  and Hawley  experimental  (1972) f o r aqueous s u s p e n s i o n s of  p o l y s t y r e n e s p h e r e s , and of U r i c k (1948) f o r aqueous  suspensions  of q u a r t z a n d k a o l i n i t e . B e c a u s e t h i s r a t i o a l l o w s t h e importance  o f t h e two a b s o r p t i o n m e c h a n i s m s t o be e v a l u a t e d , i t  has c o n s i d e r a b l e p r a c t i c a l v a l u e . I n p a r t i c u l a r , of  relative  the a t t e n u a t i o n i s greatly  simplified  the  calculation  i f i t c a n be shown t h a t  thermal absorption i s n e g l i g i b l e . In  principle,  directly  from  partial The  the  advantages. a  is  formal  the  does  been  throughout  obtained  coefficients and  offer  Hawley  of t h e (1972).  several d i s t i n c t  formalism results  in  at  of the r a t h e r t e d i o u s a l g e b r a .  that the path t o the i n v i s c i d  2.1  non-conducting  the m a n i p u l a t i o n of the e q u a t i o n s , i n the reduction t o the loss  i s a discussion  case,  Scattering  including  scattered sphere  ratio  of  Faran's  (1951) shells  i s a l s o d i s c u s s e d . The  waves  from t h e s e p a r t i c l e s a r e compared t o t h a t from a s o l i d  conduction  sphere  review  summary  i n the i n v i s c i d  s p h e r e s , a n d by s p h e r i c a l  analogues  i n the long-wavelength  heat  of s c a t t e r i n g  a  by f l u i d  t h e i r p o s s i b l e marine  solid  have  obvious.  solution.  a  however,  approximation  non-conducting  of  for  simplification  clear  Section  and  could  The u s e o f t h e p h a s e a n g l e  made t h e f i n a l quite  expressions  approach,  T h i s , and t h e f a c t limit  results  s c a t t e r e d waves d e r i v e d by A l l e g r a  present  least  these  and  limit.  viscosity  In s e c t i o n  the  Allegra-Hawley  the  effects  on t h e wave s c a t t e r e d by a  a r e e x a m i n e d . S e c t i o n s 2.2.1 of  2.2  and 2.2.2  theory.  For  are the  largely reader's  13  convenience,  a list  of s y m b o l s i s i n c l u d e d i n A p p e n d i x  1.  Table I . Developments i n the theory of scattering and a t t e n u a t i o n o f s o u n d i n d i l u t e s u s p e n s i o n s and e m u l s i o n s . Wave S c a t t e r e d by a S i n g l e P a r t i c l e R a y l e i g h (1896): f l u i d s p h e r e i n an i n v i s c i d , n o n - c o n d u c t i n g fluid at l o n g w a v e l e n g t h s . Faran (1951): solid or fluid sphere i n a v i s c o u s , nonconducting f l u i d at a l l wavelengths. M o r s e and I n g a r d ( 1 9 6 8 , p . 4 3 5 ) : f l u i d sphere i n a v i s c o u s , h e a t - c o n d u c t i n g gas a t long wavelengths. Attenuation * E p s t e i n (1941): solid or fluid spheres in a viscous, nonconducting f l u i d . • E p s t e i n and C a r h a r t ( 1 9 5 3 ) : f l u i d spheres i n a v i s c o u s , heat-conducting f l u i d M o r s e and I n g a r d ( 1 9 6 8 , p . 4 3 5 ) : fluid spheres i n a v i s c o u s , h e a t - c o n d u c t i n g gas at l o n g wavelengths * A l l e g r a and H a w l e y ( 1 9 7 2 ) : extension of E p s t e i n and Carhart (1953) to include solid scatterers * These a u t h o r s e x p r e s s e d the a t t e n u a t i o n i n terms of the c o e f f i c i e n t s of the p a r t i a l scattered waves, but did not d e r i v e e x p l i c i t e x p r e s s i o n s f o r the s c a t t e r e d wave.  14  2.1  The  2.1.1  I n v i s c i d , Non-conducting  Solid  Sphere  Consider consisting  the p a r t i c l e  t o be a m o v e a b l e s p h e r e o f r a d i u s  o f an e l a s t i c ,  Such m a t e r i a l a d m i t s shear  Case  isotropic material ofdensity  the p r o p a g a t i o n  of both  waves w h i c h h a v e p h a s e v e l o c i t i e s and c'  = (*'+2y  2  )/f>:  a,  compression  ^ . and  wavenumbers g i v e n by  , k '=u,/C  (2.1)  c  and '  c  s'  2  =X/A'  respectively, (Sokolnikoff ambient  • k;=^/c ' A ' and ^  where 1956,  fluid  (2.2)  s  p.66)  and  is inviscid,  a r e Lame's e l a s t i c  primes denote  constants  the scatterer.  o f d e n s i t y p , i n which the 0  The  velocity  of sound i s C  where  = l/Tffo  2  (2.3)  )\ i s t h e a d i a b a t i c c o m p r e s s i b i l i t y  and k = u j / c t  i s  the  wavenumber. In  spherical  t r a v e l l i n g along p^  polar  coordinates  t h e p o l a r a x i s i s g i v e n by t h e  a  plane  o  (2.4)  c  Faran  (1951),  wave  r e a l part of  = p exp[ i ( k r c o s e - to t ) ]  where p i s t h e s o u n d p r e s s u r e . D r o p p i n g following  ( r , e , <f>)  the s o l u t i o n  the time dependence a n d f o r the  l a r g e d i s t a n c e s from a sphere c e n t r e d at the  s c a t t e r e d wave a t origin  takes t h e  form p where  = p e x p ( i k r ) £ ^ (2n+1 ) i s i n ^ e " ? " P„ ( c o s 0 )/k r -  r  D  the P  c  n  ( c o s e ) a r e L e g e n d r e p o l y n o m i a l s . The  ( >] ) o f t h e n t h p a r t i a l n  wave i s g i v e n by  c  (2.5)  phase  angle  15  {tan < ( x ) + t a n ^ ( x * tan;?,, =  , s')}  tano^ (x)  (2.6)  {tan ^  ( x ) + t a n J ( x ' , s ' )} n  where  in  tan^(x)  = -  j (x)/n (x)  (2.7a)  tan^(x)  = - x j ; (x)/j„ (x)  (2.7b)  tan^(x)  = -xn; ( x ) / n  (2.7c)  which  x=k a, c  spherical on the  n  x^k^a,  Bessel  the Bessel  n  s'=k 'a, a n d  functions  The  the result  These  values  a r e such  displacement  and  zero  shear  by  Hickling  of  fluid  stress,  (1962),  solely that  and  of  n (x)  the  kind.  with  the material  through  are  n  second  differentiation  properties  affect  and  n  of the f i r s t  denote  sphere  equal  j (x)  s  functions  argument.  (x)  n  the  Primes  respect  to  constituting  the  values  of  tan § . n  the c o n d i t i o n s at t h e boundary and. s o l i d ,  continuous  are satisfied.  Faran's  result  Noting  an  f o r the tan$  normal error  n  may  r=a;  stress, observed  be  written  as  tancf„ =  A  tanecjx' ) tanWx' ) + 1  '  S  2:  (n +nj (n +n-1 ) - s ' + t a n * ( s ' ) 2  2  (2.8)  2  P  n +n-sj_ + 2tan^(x' ) 2 tan^(x')+1 2  In  (n +n) (1+tan<(s' ) )  2  the long-wavelength  2  ( n + n - i ) - s ' +tan<<(s' ) 2  limit  2  (x,x',  s'<<1),  (2.8) becomes  fts' {(n+1 ) ( 2 n + 3 ) - n ( 2 n + 1 ) ( 2n + 3 ) s j _ + ( 2n+1 )s_L } pi 2x' 2 2  2  2  2  tanfi "  where  =•  (2.9)  { s ' [ y - ( 2 n + 1 ) ( 2 n + 3 ) s _ l _ ] + 2 ( n - 1 ) ( 2 n + 3 ) [ c [ s ^ - ( n + 1 ) (n + 2) ]} 2x' 2x' 2  y=2(n +3n+l) 2  tan § = 0  tan  2  2  2  2  and q=(2n +4n+3). 2  -x ^/3K 2  §, = pjpj  -  F o r n=0  and  n=1,  (2.10a) 7( 'x /5 2  f  ?f  (2.10b)  16  7^ = 1 / ( A '  where  (Sokolnikoff tan to ( k  c  a )  k  2  3r  the  Stern a  2.1.2  F l u i d  c' Note  of  case  the  In  tan$  is  n  of  order  (2.10b)  i s  a  special  case  as  expression  i n Epstein  (2.12)  t  dropped. of  can  Goodman a n d  their  be  result  obtained  from  (1941).  case  of  a  f l u i d  sphere,  i n  which  the  speed  n=0  (2.13) (2.1)  =  and  (2.2)  may (2.6)  be  (2.13)  in  the  form  of  i f  of  (2.8)  i n  (2.14)  reduces  long-wavelerigth  [  -  2  (2.5),  and  are  n  that  the  Morse  * ( x ' ) . pJp?  - t a n  x'  to  The solution  recast  the n  reduce  (yu! ) v a n i s h e s .  i n  shown  =  n  / ( 2 n + 3) ]  l i m i t  to  (2.14)  (x'<<1),  i d e n t i c a l l y  (2.14)  pjp2  becomes (2.15)  a n d n=1,  tan  $  tan  $  The  the  t a n ^  may b e 0.  for  (51)  p.425)  n  and  rj  e x p ( i k r )  i n  T h e same  r i g i d i t y  (1968,  yw'=  (2.12)  that  tancj (x')  for  since  l/7('/?;  =  c o e f f i c i e n t  It  s u f f i c i e n t  i s  i n passing  which  i s  Sphere  consider  2  Ingard  s o l i d  (2.11)  term  s h e l l .  and  the  becomes  order  derived  of  | 7 „ | « 1 ,  •V -ft + 3( A'-/°.)cose  3  (49)  sound  compressibility  7„ )  n  (2.5)  bulk  Because  exp(-i  n  the  "\ , which  spherical  Now  is  p.69).  i n  second  equations  of  a  (1962)  for  sin^  Equation  Pr - P o c  if  =  n  order  .  3  1956,  r\  f i r s t  /*-' /3)  + 2  =  a  =  f i r s t  -7^'  x  p /p: 0  order  2  /3 -  (2. 1 6a) 7<'x /5^  (2.16b)  2  solution  f o r  the  scattered  wave  i s  17  P = Po k a 3r 2  r  »\' -"K + 3( Po" - p. ) c o s e  3  c  Comparing  (2.16)  (2.12), i t w i l l identical order  in  exp(  be  observed  form  that  the  for a  fluid  solid,  whereas  s p h e r e . When t h e t e r m s o f  waves  are  s c a t t e r e r s even t o  the tan $ are very  small  n  they are of order higher  (2.10) and  scattered  f o r b o t h s o l i d and f l u i d  5  2  c  and (2.17) t o t h e p r e v i o u s r e s u l t s  ( x ) , f o r n<1. F o r n>1, h o w e v e r ,  ( 0(s') )  (2.17)  ik r)  2pJ +f>.  T  order  in  n e g l e c t e d , t h e waves s c a t t e r e d by s o l i d a n d f l u i d  p° /po  fora  n  k a  may  c  be  spheres of t h e  same d e n s i t y , c o m p r e s s i b i l i t y , a n d r a d i u s a r e i d e n t i c a l  t o order  (k a) . 5  c  2.1.3 S o l i d S p h e r i c a l For to  the  Shell  sake of c o m p l e t e n e s s and because of i t s r e l e v a n c e  t h e s c a t t e r i n g of sound  shells  by  phytoplankton  2  +  3  ,  /  is  Equation (A),  based  on  equation  such  that  shell.  outer  (2.18)  spherical  shell  of  The p r i m e d q u a n t i t i e s  silica It  fluid  refer  i s the to  the  the s h e l l . to the  r a t h e r t h a n t h a t o f t h e s p h e r e . Suppose  f r u s t u l e o f a d i a t o m c a n be m o d e l l e d by  would  (1962).  thickness  a m p l i t u d e o f t h e s c a t t e r e d wave i s p r o p o r t i o n a l  volume of t h e s h e l l thin  3( ^ ' y j c o s e l e ' ^ p. J  A/a<<1, a n d i n w h i c h t h e c e n t r a l  material constituting The  +  ( 2 0 ) o f Goodman a n d S t e r n  (2.18) a p p l i e s t o a t h i n  same a s t h e a m b i e n t f l u i d .  the  thin  ( e . g . d i a t o m f r u s t u l e s ) , we i n c l u d e t h e r e s u l t  Pr =Po ( k c a ) 3 A "( <Y>' ~ X ) ( 1 4 A' ^ /3) 3r a H (1+4 * 7f;/3) which  with  then  be  expected  that  such  a  t h a t t h e a m p l i t u d e of t h e  18  s c a t t e r e d wave s h o u l d be c o n s i d e r a b l y by  a  solid  silica  l e s s than  that  scattered  body o f t h e same shape a n d s i z e a s a d i a t o m .  T h i s s u p p o s i t i o n assumes, o f f r u s t u l e are unimportant  course,  that  the  pores  i n . the  i n t h e f r e q u e n c y range of i n t e r e s t .  2.2 V i s c o t h e r m a l E f f e c t s The  attenuation  of  a  sound  wave  i n h o m o g e n e o u s medium i s d e f i n e d a s t h e  sum  propagating of  in  scattering  an and  a b s o r p t i o n l o s s e s . E p s t e i n a n d C a r h a r t (1953) d e v e l o p e d a t h e o r y for  the  fluid the  attenuation  of  sound  sphere,  which  of  the  are  partial  modified  c o n d u c t i o n . A l l e g r a and Hawley i n c l u d e the case of s o l i d In  the  inviscid,  s c a t t e r e d compression  the  by  in  in a  terms  of  waves s c a t t e r e d  from a s i n g l e  viscous  and  (1972)  drag  extended  thermal  t h i s treatment t o  spheres. non-conducting  wave i n t h e  case,  fluid,  three  and  waves - a  compression  and  waves i n t h e s o l i d - a r e n e c e s s a r y t o a d e q u a t e l y d e s c r i b e response  compression three  spheres suspended  medium. The a t t e n u a t i o n was o b t a i n e d s o l e l y amplitudes  shear  by f l u i d  of  the  fluid-solid  system  to  an  incident  wave. When v i s c o u s a n d t h e r m a l e f f e c t s a r e i n c l u d e d ,  new waves a r i s e  thermal compression  - a v i s c o u s s h e a r wave i n t h e f l u i d  wave i n b o t h t h e f l u i d  and  the  and a  scatterer.  M a t h e m a t i c a l l y , t h e i n c r e a s e d a b s o r p t i o n o f t h e i n c i d e n t wave i n the  presence  of  the  scatterer  a d d i t i o n a l waves. P h y s i c a l l y , conduction the and  is  i s due t o t h e d a m p i n g o f t h e s e  energy  loss arising  due t o t h e d i f f e r e n c e s  acoustically driven  temperature  from  thermal  i n a m p l i t u d e and phase of  fluctuations  the p a r t i c l e . Viscous losses are the r e s u l t  in  the  fluid  of the r e l a t i v e  19  motion of the f l u i d  and t h e p a r t i c l e .  Both e f f e c t s depend  on  a  flux  - o f h e a t i n one c a s e , momentum i n t h e o t h e r - b e t w e e n t h e  fluid  and  the p a r t i c l e .  gradients  of  This  temperature  which i s the case only the  scatterer.  -The  proportional  to  flux  and  is  appreciable  velocity  i n t h i n boundary  thicknesses  the  of  solids  and  compressibilities conductivity wavelength either  fluids  of  less  than  to s p e c i f i c of  the  the  boundary  the  layers  v i s c o u s and  10"  water g"~  6  cm  1  wave  wave or  £  where  , | k '/k;| «  T  c  10"  for with  thermal  or l e s s ) ,  2  the  than that wave  10 MHz.  fundamental t o the t h e o r y , namely  | k /k |  thermal  that  and  2  compression  s c a t t e r e r a t f r e q u e n c i e s l e s s than about assumption  s  - 1  i s much s m a l l e r  the  are  (e.g. those  heat r a t i o s of about  thermal  incident  in  high,  l a y e r s a t t h e s u r f a c e of  w a v e s . From m a t e r i a l t o be p r e s e n t e d , i t c a n be shown most  the  are s u f f i c i e n t l y  the  wavelengths  where  in  of the  T h i s p e r m i t s an  that  1  (2.19a)  k i s t h e t h e r m a l wavenumber. I n t h e f l u i d ,  the  T  additional  assumption | k /k c  s  | «  c a n be made, where k Carhart in  theory,  sections  1 s  (2.19b)  i s the v i s c o u s  The  Epstein-  as m o d i f i e d by A l l e g r a and H a w l e y , i s r e v i e w e d  ( 2 . 2 . 1 ) and  (2.2.2).  The  p r e s e n t work a r e p r e s e n t e d i n s e c t i o n s 2.2.1  wavenumber.  central  results  ( 2 . 3 ) and  of  the  (2.4).  Governing Equations The  stress tensor for a f l u i d Sij  where tensor i s  = - P V is  2/-. [e,  the Kroneker d e l t a  (Batchelor -  (  2  1967, .  p.147) i s 2  t e n s o r and t h e r a t e of  0  )  strain  20  by,; + d Vj J  The and  (2.21 )  2  ju i s  a r e the v e l o c i t y components,  the  B  shear  viscosity  p, the p r e s s u r e , i s the mean normal s t r e s s . The  stress  tensor  f o r an i s o t r o p i c s o l i d  i s (Sokolnikoff  1956, p.71) Sj £  + 2 ,'€  = A'du^-  /t  (2.22)  ij  where the s t r a i n tensor i s ej t  =  1  f  +  2V< > j x  The  u  £  dx  In  i  i t s mean s t a t e the medium i s s t a t i o n a r y  that  deviation  A' and /<.'  constants.  amplitude of the sound wave  small  non-linear  i s taken  to  and i s o t r o p i c .  be  sufficiently  e f f e c t s can be ignored. In t h i s case the  of a v a r i a b l e  from i t s mean value i s a l s o  products of such d e v i a t i o n s and  (2.23)  a r e the components of the displacement v e c t o r ,  are Lame's e l a s t i c  The  <t"i)  small,  and  are n e g l i g i b l e . Dropping these terms  time and space d e r i v a t i v e s of mean q u a n t i t i e s , the equations  of c o n t i n u i t y and c o n s e r v a t i o n P  pJv^dx;  +  of momentum  =0  (using  ( 2 . 2 0 ) become, (2.24)  (2.25) dx-  where  3  "5x-\ dx j k  dx \  6x l  k  k  the dot i n d i c a t e s p a r t i a l d i f f e r e n t i a t i o n with respect t o  time. In a s o l i d , f> '  +  P^u  L  /ax. = 0  (2.26) (2.27)  dx7  where the a c o u s t i c  3  dx\dx J k  dx \dx J k  k  p r e s s u r e i n the s o l i d i s  21  p'= which  - (  V + 2 / u ' / 3 ) .  <3u /t!x^  i s t h e mean n o r m a l  derived  ( 2 . 2 8 )  t  stress.  A  f o r the pressure i n the f l u i d ,  use a d i f f e r e n t  The  result  could  denote  the  scatterer  quantities.  e q u a t i o n f o r c o n s e r v a t i o n of i n t e r n a l energy  i sdiscussed  indetail  be  but i t i sconvenient t o  form. Primes a r e used t o  and t h e s u b s c r i p t o t o d e n o t e mean  fluid  similar  by B a t c h e l o r  ( 1 9 6 7 ,  (E) f o r a In the  p . 1 5 1 ) .  a p p r o x i m a t i o n u s e d h e r e , i t becomes ( 2 . 2 9 )  T  i s the temperature;  analogous solid  K  the thermal  conductivity.  fashion, the conservation of internal  I n an  energy  i n the  i s written ( 2 . 3 0 )  It  i s important t o note t h a t t h e v i s c o u s d i s s i p a t i o n  has b e e n d r o p p e d  from  ( 2 . 2 9 )  because  term  i t involves products of the  s m a l l q u a n t i t i e s c W ; /<3XJ . T h i s means t h a t v i s c o u s d a m p i n g o f t h e f l u i d motion and  ( 2 . 2 9 )  is  greatest  ( t h e s o u n d wave) a r i s e s  through the divergence of the v e l o c i t y i n the neighbourhood  damping o f t h e energy the  momentum  the  particle. Similarly,  mechanical  flux  i n t h e sound  of  ( 2 . 2 5 )  field,  which  the scatterer. Viscous  wave r e s u l t s  primarily  from  ( d r a g ) n e c e s s a r y t o overcome t h e i n e r t i a o f  t h e term  pressure  second c o e f f i c i e n t ( 2 . 2 9 ) .  from t h e c o u p l i n g of  of  i n Batchelor's  (Batchelor viscosity  1 9 6 7 ,  has  expression  p . 1 5 4 ) ,  been  f o r the  involving  dropped  to  the  obtain  The m e c h a n i c a l p r e s s u r e c a n t h e r e f o r e be i d e n t i f i e d  with  22  the  thermodynamic e q u i l i b r i u m p r e s s u r e , which  from  t h e e q u a t i o n of s t a t e .  heat  c o n d u c t i o n p r e s s u r e changes w i t h i n  reversible,  except  heat  expansion  cycle.  each  conjunction  medium w i t h two  state variables The  details  6/dt  = -icj,  p  may  itself  of the p a r t i c l e .  c y c l e , and  the  three  implicit  is  conservation  Because  a c t s as a  T are reduced  be  found  t o two  equations,  coupled  i n E p s t e i n and  the  equations.  Carhart  (1953).  With  fluid  2  (2.31a)  2  /  the  in  E and  i um.\ V(^- v) + i t j c a ^ T - i t o A t V v = 0  2  of  reduced.  r e l a t i o n s b e t w e e n p and  and  are  as a source d u r i n g the  to the temperature,  these equations are, f o r a  co v + / c J -  fluid  In both c a s e s , the amplitude  pressure, being proportional In  the  i s i n c l u d e d i n (2.29) the s c a t t e r e r  sink during a compression  subsequent  determined  I t a l s o means t h a t i n t h e a b s e n c e o f  i n the neighbourhood  thermal conduction  c a n be  0  and ( r - 1 ) 7 - v - i c j T - yg- V T 2  where  Y = C /C p  of sound, thermal  ¥  (2.31b)  i s the r a t i o of s p e c i f i c  i s the c o e f f i c i e n t  heats, c i s  of t h e r m a l e x p a n s i o n  the  and  speed  cr i s t h e  diffusivity.  In a s o l i d ,  the e q u i v a l e n t equations  oo u+(c,' + m'Xv(V-u)2  =0  2  c,' fi VT+ 2  ,  are (2.32a)  /X'^7 U=0 2  and (-ih)) ( y ' -1 ) V-u  - iojT' -  r'<r' V T' 2  =0  .  (2.32b)  where c/ = ( \'+2y/3)/p: 2  = 1/(/*.')  (2.33)  23  The field The  equations  i n the fluid  problem  spherical  and  at  The  solid  are  to these  respectively. equations  t h e n be s p e c i a l i z e d  conditions  at the surface  acoustic  in  by t h e use  of the sphere  i n the f l u i d  represented  by  and d i s p l a c e m e n t  scalar  potentials  field  <f> a n d  in  vector  that  Vx Vx  A  (2.34)  A'  (2.35)  r/-/t-0 a n d f  = <fl + (j> (f)  and  c  thermal fc=  (fs  +  In the  wavelike  fluid (2.37)  the  of symmetry,  to three V <t> 2  scalar  potentials  2  +k £ c  + k <^ 2  7  V f\^\l  T  A=(0,0,A^) and  the f i e l d  equations 2  c  2  f o r the compression  4>r  solutions,  V (p  potentials  f o r the incident  and  waves.  Because  where,  T  being  r  scattered  <^ a r e t h e s c a l a r  waves.  <t>o  and  reduce  (2.36)  r  which  0  field  A such  = - ? f+  where  (j)  scatterer,  the  Solution  u = -fif'+  and  represent  solutions  w h i c h must  boundary  velocity  potentials  in  (2.32)  infinity.  2.2.2 G e n e r a l  v  general  coordinates,  appropriate  and  medium a n d t h e s o l i d  i s to find  of  the  (2.31)  equations  A'=(0,0,A^). (2.31) and  Assuming (2.32)  each  of the form  =0 = 0  (2.38)  4 = 0  f o r the scatterer,  the primes are understood. In t h i s  way  24  the def  wavenumbers of t h e c o m p r e s s i o n , t h e r m a l  a n d s h e a r waves  are  ined. In  the fluid  K  medium,  = u> [ 1 - iu> {  2  )  2  c  k  2  k  2  c  2  * i  o  -  (2.39a)  3^  2  /c  w  (2.39b)  = iw^//.  provided  (2.39c)  the temperature i s given  T = [b <£ c  c  by  +b <j> ]/(-i«J ) r  (2.40)  r  where  b  c  = --r  [  -  b  T  = - y  [ CJ  2  /cl-  - / c - 4 W.\ 2  2  (2.39a)  ?°  V  '  3  y  c ,6  Note  4icjAt.\ k  and (2.39b) h o l d  2  k  2  ]  (2.41a)  ]  (2.41b)  only  i f | k /k t  T  | « 1 ,  | k |~u>/c e  and w«3 o c /(4 u.y ) 2  /  For  0  y  water, the last  much  less  cases. term  than  10  I t should involving  equation chosen  a solid,  k/  2  =  w  c' 2  k' 5  2  c  s  | «  1  requires  Hz, which w i l l  1 1  also  be n o t e d t h a t  the  second  (7.4) i n Epstein  In  | k /k  condition  f o rthe stress  k;  or  that  the  frequency  n o t be a l i m i t a t i o n 02.39a)  coefficient  and Carhart  does of  (1953)  not  because  i n most  include  viscosity  be  a  as does  of t h e form  i n (2.20)  the equivalent  relations are  1 - i c j o-' ( y ' - 1 ) ( /3) c' (A' +2^')  2  (2.42)  (2.43a)  2  2  = i c j /cr'  (2.43b)  = }:^ /^  (2.43c)  2  25  provided T'= b '#  +b '  e  T  ft  (2.44)  where b' = -y'  [ w  2  -  /c,' + 4/,'U/  ]  (2.45a)  b' = -y'  [ w  2  -  /c,' + 4 V U ;  ]  (2.45b)  c  T  2  2  2  2  A g a i n t h e e q u a t i o n s f o r k' a n d k' h o l d o n l y i f | k' | ~ w / c ' c  and  | k '/kT-|«l. R a t h e r  was  case  c  than a r e s t r i c t i o n  e  the  T  i n t h e ambient  fluid,  on t h e f r e q u e n c y ,  i n the s c a t t e r e r  as  y' must be  v e r y c l o s e t o 1. Until with  this  solid  p o i n t the development  scatterers.  where t h e s c a t t e r e r identical  been  I t i s of i n t e r e s t  i s fluid.  i f c)u/<3t=v,  has  Equations  <£=-icj$'  and  concerned  only  t o c o n s i d e r the case  (2.34)  and  (2.35)  are  A=-icu A' , a n d ( 2 . 3 9 ) a n d  ( 2 . 4 3 ) become e q u i v a l e n t i f  ci  2  _  provided fie //*,'  w «  2  which i s e q u i v a l e n t t o (2.42). Equations equivalent  i f c,' i s r e p l a c e d by c' a n d  (2.40) and (2.44) a r e e q u i v a l e n t i f the fluid  field  ( 2 . 4 1 ) and  equations  for a solid  f  by - i -*-  (2.45)  u>yu  y  a  . Equations  #'/(-io> ) .  (2.32) reduce  are  Finally,  t o those  fora  ( 2 . 3 1 ) p r o v i d e d -icju=v a n d /t'-*-iww,. The  solutions w i l l  t h e r e f o r e apply t o both f l u i d  and  solid  26  scatterers,  and the r e s u l t s o b t a i n e d  specialized k ',  ,  c  t o the  , b^,  and  case b^  of  by  for solid  fluid  their  ones  fluid  p a r t i c l e s can  by  simply  equivalents  be  replacing unless  noted  otherwise. Notice | b /b c  |  T  that  and  since  | k /k |«1 c  and  T  | b ' /b^. | a r e a l s o <<1.  | k,!/k_;|«1,  F u r t h e r m o r e , i n c a s e s where  c  k a k' , w h i c h i s t r u e  f o r most l i q u i d  water,  | bJ/b |<<1 as w e l l . These  c  c  | b / b | | « 1 and c  prove very  2.2.3  The  Boundary-Value  Problem  solutions  equations  coordinates finite  and  of  solid  particles  in  relations will  expressions.  (2.38)  spherical  polar  w i t h symmetry a b o u t t h e p o l a r a x i s , a n d w h i c h  remain  a t t h e o r i g i n and a t i n f i n i t y ,  in  a r e , i n the f l u i d  £  i " (2n+1 ) j„ ( k r ) P„ ( c o s e )  £  i ( 2 n + 1 ) A„h„(k r) P (cos 6 )  2  i " ( 2 n + 1 ) B h ( k r ) P„ ( c o s e )  j£  i"(2n+1) C.h  medium,  c  £1  (2.46)  n  t  n  i n the s o l i d £'=  and  T  useful in deriving explicit  The  that  n  T  (k^r)dP  n  n  n  (cos 6 )  scatterer,  i"(2n+1) A ^ U ^ r )  PjcosQ)  oo  (2.47)  CO  (\1=  The  C  values  i"<2n+1.)  j ( k ^ r ) d P ^ (cos© ) n  o f t h e unknown c o e f f i c i e n t s A„ ,B„ ,C ,A^ ,B^, and  d e t e r m i n e d by t h e b o u n d a r y  are  n  conditions  at  the  surface  of  the  27  sphere.  These  conditions  tangential velocity, tangential  stress  and H a w l e y only  are  temperature, heat be  limit,  the  f l u x must be d r o p p e d to  be  be  strain e-  found  velocity, stress  (1953).  in  term.  no-slip  In  conditions  to  (2.23)  those"  in  Sokolnikoff  ( u ) by t h e r a t e o f s t r a i n  on  used  spherical  We  and  note  in  inviscid  (continuous  temperature  and  c o n d i t i o n s c a n be by  Faran  polar  (1956, p.184). (v)  the  condition  - t h e o t h e r boundary  equivalent  Expressions f o r the may  radial  Carhart  from t h e f i r s t  t a n g e n t i a l v e l o c i t i e s ) and the  shown  flux,  radial  i n A l l e g r a and Hawley's e q u a t i o n ( 6 e ) , i n which  a f a c t o r of 2 i s absent non-conducting  the  c o n t i n u o u s . They may be f o u n d i n A l l e g r a  (1972) a n d i n E p s t e i n a n d  a misprint  heat  that  these  (1951).  coordinates  By r e p l a c i n g t h e relations,  the  ( 2 . 2 1 ) may be o b t a i n e d . The  resulting  (a) R a d i a l  equations are :  velocity  xj;(x)+xA h;(x)+tB h;(t)+C n(n+1)h (s) n  n  n  n  (2.48a)  = (-iuu J f x ' A j j ^ x ' l + t ' B ^ j ^ t M + q n i n + D j J s ' ) ] (b) N o - s l i p  condition  j„(x)+A h„(x)+B^h (t)+C [h (s)+sh;(s)] n  n  = (-icj (c)  ){A^j  n  n  n  ( x ' )+B; j„(t' )+C^[ j"„(s' )+s" ] \ ( s ' ) ] }  Temperature  b [j (x)+A„h (x)]+b B h (t) c  (2.48b)  n  n  = (-ico (d) H e a t  T  n  n  (2.48c)  H b ' A ^ U ' K b ^ j ^ f ) ]  flux  b [xj;(x)+A„xh;(x)]+B b th^(t) c  n  = (-ico  T  ) j T f A ^ ' x ' j ; (x' ) + B ; b ^ f j j t f ) ] K  (2.48d)  28  (e) R a d i a l s t r e s s (-icjp.  a + 2 / , x ) j„ ( x ) + 2 u x j„"(x)+A [ ( - i c o ^ a + 2 2  2  2  0  /  2  a  n  x ) h (x) 2  / W < >  n  + 2 x h ; ' ( x ) ] + B j (-ioj o a + 2 , t ) h ( t ) + 2 a t h ; ( t ) ] 2  2  A  /  2  e  /  2  0  n  y  ,  0  -C„ 2 n ( n + 1 ) [ h ( s ) - s h ^ ( s ) ] A  =  (2.48e)  n  [ (- u  2 J  , / J o  a + 2 X x ' ) j ( x ' ) * 2 / x ' j " ( x ' ) ]+B,| [ ( V ^ a ' 2  2  2  n  n  +2/*'t' ) j ( f ) + 2 u ' f j " ( f ) ]-C«2y n(n+1 ) [ j„ ( s ' ) - s ' j ' ( s ' ) ] 2  2  n  /  (f) Tangential  n  n  stress  ^ { x j ; (x)-j (x)+A„[xh;(x)-h„(x) ]+B„[th,; ( t ) - h ( t ) ] n  n  + C j s h „ " ( s ) + (n +n-2)h„(s) ]/2} 2  (2.48f)  2  =/t'{A;[x'j:(x'  (x' ) ] + B A [ t ' j ^ ( f ) - j „ ( f  +C;[s' j;'(s') + ( n + n - 2 ) j ( s ' ) ] / 2 2  2  r i  t=k a,  )]  }  where  x=k a,  except  i n t h e case of t h e s p h e r i c a l Hankel and B e s s e l  c  in which case they are  identical  exceptions. as  Davis  s = k a and t h e primes denote t h e s c a t t e r e r  r  5  denote d i f f e r e n t i a t i o n .  to  that given  Carhart This  of  those  obtained  by  and  Allegra  and  v e c t o r p o t e n t i a l i s d e f i n e d as t h e n e g a t i v e  attenuation  of  the  incident  wave,  (1953) have shown, d e p e n d s e x p l i c i t l y simplifies  on  with obtaining r e s u l t s  as  E p s t e i n and  the  k  n  only.  t h e p r o b l e m . F u r t h e r m o r e , we a r e  i n t e r e s t e d p r i m a r i l y i n the long-wavelength l i m i t  For  ( f ) ,  2  here.  considerably  content  ( 8 ) , w i t h two  ( 1 9 7 9 ) a l s o o b s e r v e d . The s e c o n d i s t h a t t h e C„ a n d C,|  Hawley because t h e i r  The  (2.48)  i s t h e s i g n of t h e (n +n-2) terms i n  terms a r e a l l the n e g a t i v e  of  The e q u a t i o n s  A l l e g r a and Hawley's e q u a t i o n s  The f i r s t  functions,  and  shall  be  f o r n=0 a n d n=1.  n=0, t h e b o u n d a r y c o n d i t i o n s on t h e t a n g e n t i a l v e l o c i t y  stress  are  such  that  every  t e r m c o n t a i n s dP„/de =0 a s a  29  multiplicative condition  f a c t o r . Of  (2.48c)  d i v i d i n g by b  (see  the  Carhart,  remaining be  further  by. d r o p p i n g a l l b u t t h e B  T  paragraph  in  Section  equations,  simplified  and  0  the  B„  terms  2.2.2, a n d E p s t e i n  and  1953).  For  n=1  a similar  argument  be u s e d t o show t h a t t h e B, but  four  on t h e t e m p e r a t u r e may  after  final  the  (2.48c)  and  o t h e r words,  ( E p s t e i n and C a r h a r t ,  1953), can  and B,' t e r m s a r e n e g l i g i b l e  (2.48d),  which  may  t h e r e f o r e be d r o p p e d . I n  t h e r m a l e f f e c t s a r e u n i m p o r t a n t f o r n=1  equations are reduced t o - f o u r  in a l l  i n w h i c h B,  and  B/  and t h e s i x are  set  to  c o n d i t i o n s and t h e  no-  zero.  2.3  The  I n v i s c i d Non-Conducting  In slip  this  limit,  condition  e q u a t i o n s , jj  the t h e r m a l boundary  may  be  ,B„ ,B^ and C  a  Limit  dropped.  In  the  remaining  are set to zero. Equation (2.48f) then  n  becomes C„'=  -2A„ [x' j ; ( x ' )-j„ (x* ) ] s' j„"(s' ) + ( n + n - 2 ) j 2  2  n  (2.49) (s' )  Defining F ( x , A ) = j„(x) R  + A„h„(x)  n  and t a k i n g  the r a t i o of  ( 2 . 4 8 a ) and  (2.50) (2.48e)  xF '/F = t a n <| (x' , s ' ) n  n  o  where  tan §  easily  shown t h a t i f  A„  n  is  g i v e n by  = -isin-| exp(-i>] n  and t a n c£„=xF^ /F  n  r t  ( 2 . 8 ) , and xF ' =x j \ (x) + A x h ^ ( x ) . I t i s n  n  )  , then tan/|  (2.50a) n  i s as g i v e n  (2.48) reduce t o F a r a n ' s r e s u l t  i n the  i n ( 2 . 6 ) . The e q u a t i o n s  limit.  30  This Epstein  leads and  the  departure  Carhart  viscothermal xF„' / F „  to  (1953)  effects  are  rather  than  tan $ =  x F ; /F„  n  2.4  The Long-Wavelength  for  aqueous the  and Hawley  and  theory  I  k '/k  |  k '/k  wavelength - t a n r j . =xl~ x /3 3  c  that  s  s  s  limit  When  solved  for  by  the  (1972)  n=1  term  only  reduced  to  term  to  approximate  found  that  in  attenuation  from  k a>0.05,  and  for  for  k,.a>0.2.  the  region  c  On t h a t  basis,  k a<0.1. c  Term  equations n=0.  (2.48)  the  1  (2.52)  | «  1  (2.53) (see  equations  2  added  to  | «  1  the  reduce  for  £ 0  With  readily  (A2)  n +4b;tarw.(t' ) b 's' T  (1972).  replaced  spheres, the  the  n=1  applies  P°/f>°  0.1;$  from  the  (n=0)  (2.19),  now be  polystyrene  from  equations  that  of  exceeded  The I s o t r o p i c  are  are  by  Limit  Allegra  a n d 1.  that  equations  taken  1.  n=0  term  and Hawley  (2.6)  w i l l  Using three  in  n  (2.48)  following  2.4.1  the  equations  approached the  i n Appendix  suspensions  n=2  included,  approach  (2.51)  details  forms  the  and A l l e g r a  The t a n §  The  The  are  A„ .  from  Appendix  (A2)  reduce  1),  restrictions  then  2  T  e  K'b 'b x' K b b 'x  A + 2 a ' / 3 ) f l - K ' t a n ^ f )\ x'+2y ) \ K tany(t) ,  long-  to  3s' H - K ' b ; V b . - p.\ - 1 + 4x~*~l K b /\b ' pi) v  i n the  y  T  2  c  T  c  2  (2.54)  provided (r'-!)|  t a n oc ( t ' ) / t ' o  2  | «  s ' /4x ' 2  2  ~ 0. 1  (2.55)  31  It solid  i s t h e c o n d i t i o n (2.53) which r e s t r i c t s particles.  The f u r t h e r r e s t r i c t i o n  by A l l e g r a a n d H a w l e y Equation  (1972) and  2.4.2 The D i p o l e  i s examined  of t h e f l u i d and vanishes.  the result  and again  to solid  invoking  (2.53) and  s c a t t e r e r s , the equations  become ( p,-pJ ) ( t a n y, ( s ) + 1 )  tann, = x / 3 - (f,  (2.56)  +2f>: ) ( t a n y, ( s ) + 1 )+6(p.  3  which i s e q u i v a l e n t  -/>; )  t o (15) i n A l l e g r a  and Hawley  gives theappropriate  result  2.4.3 The A t t e n u a t i o n  o f t h e I n c i d e n t Wave  Epstein  and Carhart  wavelength l i m i t ,  (1953)  2  0  €  3  suspension particle  as  (2.57) of suspended  t h e range  may be c o n s i d e r e d such  of  region of  dilute,  On  (1967), t h e  a p p e a r s t o be v a l i d t o linear  concentrations  as  material.  ( 1 9 4 8 ) a n d Hampton  o f a b o u t 8-9%. T h i s  interaction,  i n the long-  = *.+ 5f,  d e p e n d e n c e o f «r on c o n c e n t r a t i o n  taken  ( s = °° ) .  h a v e shown t h a t  i s t h e volume c o n c e n t r a t i o n  concentrations  and  f o r thea d d i t i o n a l attenuation  t h e b a s i s o f e x p e r i m e n t s by U r i c k linear  limit  (1973)  wave due t o t h e s c a t t e r e r s i s g i v e n by  * = -3£ R e [ A + 3 A , ] / 2 k a where  i nthe inviscid  thecoefficient  of t h e i n c i d e n t p r e s s u r e  is  1.  (n=1) Term  restricting  (A10)  i n Appendix  (K'=0), t h e second term  In t h e long-wavelength l i m i t , so  to  ( 2 . 5 5 ) was n o t assumed  (2.54) i s independent o f t h e v i s c o s i t y  in the non-conducting l i m i t  the result  over  dependence which  the  meaning t h a t t h e e f f e c t s o f  multiple  scattering,  may  be  ignored. In  our case  A  n  i s given  by ( 2 . 5 0 a ) ,  a n d i t c a n be shown  32  that Re (A, ) = I m [ t a n ( 7 „ ) ] for  (2.58)  | 7„|<<1. Re a n d Im r e p r e s e n t  their  arguments.  Because  the real  thermal  and imaginary  and v i s c o u s  completely  decoupled i n theapproximate r e s u l t ,  imaginary  parts  thermal  of  effects  (2.54) and (2.56) s h o u l d  as discussed a t t h e beginning  Proceeding definitely  for  the  h o l d s , and a l s o  case  give t h e r a t i o of  |s1»1,  order  terms  of t h i s s e c t i o n .  | t'|»1  taking  are  t h e r a t i o of the  t o viscous absorption providing thehigher  are n e g l i g i b l e ,  p a r t s of  f o r which (2.54)  and  (2.55) (2.56)  become Q •tan/?. & f : - Y, 3( 1+i) ( y ' - l )dl2al a 3c,' x /3 2  | k a | , | k 'a|»1  (2.59a)  | k a|»1  (2.59b)  T  T  2  3  -tanc], = pi ~ p x /3 p + 2f>: a  - (Hi)3^.'-/t ) *d/  3  \f>*2p:  J  s  a_  where Q= 3c. p - K ' b ^ V bt-A." 4c.' K" b~ TA/ b\ '~ c l, S V\ Po 2  1 +K' b ' b c  2  T  c  1+K'cr  T  p  The p a r a m e t e r s d ' T  viscous  a n d d„ a r e t h e t h i c k n e s s e s o f t h e t h e r m a l a n d  boundary  layers  i n the scatterer  r e s p e c t i v e l y , and a r e given  1  2  T  v  = ^2/l  M  t h e medium  0  2  (2.60a)  (2.60b)  to viscous absorption i s  0  .losses.  /  r/z  R , = I m ( t a n /y. ) = _2_( y'-1 ) cI^2 I 2 Im(3tan7,) 9 It w i l l  =(2K'/co o 'c; ) "  (2/i,/p.u>)  =  The r a t i o o f t h e r m a l  and  by ( M o r s e a n d I n g a r d , 1968)  d ' = V2/| k; | = ( 2 o ' A > ) /  d  (2.59c)  - 1  K <r'  2  be n o t e d t h a t t h i s  ratio  (2.61 ) k:  /a.' " p.  does  not  include  scattering  33  2.4.4 C o m p a r i s o n The (2.61)  with  values  Experiment  in  T a b l e I I may be u s e d t o e v a l u a t e t h e r a t i o  f o r aqueous  suspensions  of  spheres, with the h e l p of the r e l a t i o n y'-l where T  a  polystyrene (Pippard  and  quartz  1966, p.61)  "T^'V^'Cp  (2.62)  i s the absolute temperature.  T a b l e I I . P h y s i c a l p r o p e r t i e s a t 20 °C Water ; " 1  density thermal c o n d u c t i v i t y s p e c i f i c heat thermal exp. c o e f f .  A  K C  g cm" cal°C" cm-'s" cal°C- go - 1 3  1  3  P  V-  viscosity speed of sound  0.998 1.41 x 10" 1 .000 2.1 x 10"" 5.77 x l O ' 1.002 x 10" 1 483  C  1  1  1  c  3  2  g cm m s  s"  - 1  1  _1  Polystyrene" density thermal c o n d u c t i v i t y s p e c i f i c heat thermal exp. c o e f f .  P"  comp. wave s h e a r wave  c  K  c  speed speed  C  Q u a r t z and G r a n i t e ; 2  3  P  s  P'  K  P fi C  y-i c  speed speed  g cm" cal°C-'cm''s" cal°C-'g°C" 3  1  1  1  m s~ m s"  1 1  3  density thermal c o n d u c t i v i t y s p e c i f i c heat thermal exp. c o e f f . comp. wave s h e a r wave  1 .055 0.27 x 10~ 0.287 2.64 x 10-" 0.069 2380 1 1 00  C  2.65 8.4 x 10" 0. 1 92 3.4 x 10" 5.2 x 1 0 51 00 3200  g cm cal C"'cm-'s" cal°C-'g-' °C" ' - 3  3  5  0  1  3  m s" ' m s1  s  ' B a t c h e l o r (1967, pp.595-597) C l a r k ( 1 9 6 6 , p . 9 2 , 167, 197-201) Weast ( 1 9 7 8 / 1 9 7 9 , p. E-16) " A l l e g r a a n d H a w l e y (1972) 2 3  The  thermal d i f f u s i v i t y  cr = K/( C Po  with the r e s u l t  p  ( cr ) i s g i v e n by  )  that  (2.63) f o r polystyrene, the r a t i o R  01  (2.61) i s  34  R  and  =  0|  12.5  x  \0-*{{2p:  + p )/(p.'-  p.)]  =  2  a  3.6  (2.64a)  for quartz, R  = 3.72  01  Note  that  each  case.  x  ] 0 - [ ( 2 f ' + o ) / ( : - p . ) ] = 5.4 u  evaluating  a  P  following  c  )g>  (-1.274 and  approximate  forms  were  b ' = c' k ; c,' ^'  •  2  2  T  2  2  results  deserve  some d i s c u s s i o n .  In the f i r s t  t h e y a p p l y o n l y t o t h e c a s e where t h e s k i n d e p t h s v i s c o u s waves i n t h e f l u i d and  of  thermal  independent  of  /*m)  numerical  radius  of  the  F i g u r e 8 (a=0.504 ^m)  of  with data  Over  scattering  c^/o?,  the  t h e v a l u e s of  solution  shown t o a g r e e  and  and  i n which  spheres.  radius.  solid  Secondly,  v i s c o u s e f f e c t s a s e m b o d i e d by  either  thermal  the  (2.61) i s  particle  or  the  o f t h e i n c i d e n t wave. T h i s i s i n a g r e e m e n t w i t h F i g u r e  (a = 0.653  ( 1972),  to  of the  place  t h e t h e r m a l wave i n t h e  p a r t i c l e a r e much l e s s t h a n t h e p a r t i c l e  7  in  P  2  frequency  used  T  2  -( y'-1 )u p' c'  These  ratio  -0.658) i n  b = _kl  2  c  /3  and  (2.64b)  3  Q:  b = - ( y -1 b'=  /  t h e v a l u e o f Q i s o f o r d e r -1 The  x 10'  2  o  the  the  and  equations  frequency  constant, in quite  Urick  able  was  of q u a r t z and  o n l y v i s c o u s and  ~°(, ,  determined  range  to  but  3-20  from  f o r which  not o n l y i s  a and  polystyrene k a<0.1 c  their  r e a s o n a b l e agreement w i t h  kaolinite  scattering  MHz,  of  i t v a r i e s b e t w e e n 4.2  account  Hawley  (2.48), are p l o t t e d  f o r aqueous s u s p e n s i o n s  w i t h a mean of 5.4,  suspensions  0  losses are unimportant,  relatively  (1948)  o(  i n A l l e g r a and  ratio and  6.7  (2.64a).  f o r a t t e n u a t i o n i n aqueous  (0.5^a<10/*m) by c o n s i d e r i n g  l o s s e s over the frequency  range  1-15  35  MHz, i n a g r e e m e n t w i t h  (2.64b). I t i s concluded that  d e n s i t y of the p a r t i c l e velocity  of  i s c l o s e t o that of water, the  the surrounding  i s reduced a c c o r d i n g l y , important,  fluid  importance  ( 2 . 6 1 ) may be  of  viscous  suspensions of s o l i d p a r t i c l e s particle  sizes  depth c r i t e r i a  apply.  used  and  to  thermal  i n water,  These c o n d i t i o n s size  f o rwhich  f r e q u e n c y o f 200 k H z , q u a r t z  evaluate absorption  in  f o r frequencies  or  and t h e s k i n  impose an u p p e r a n d l o w e r  ( 2 . 6 1 ) may be u s e d .  particle  the  For a  d i a m e t e r s must be < 250/tm  >2 am, a t w h i c h k a a n d k 'a=1. The a p p r o a c h c a n be e x t e n d e d /  t  to smaller  diameters,  c  h o w e v e r , by t a k i n g t h e r a t i o o f  (2.56) and e v a l u a t i n g t h e B e s s e l Returning  to  functions  (2.61) a n d ( 2 . 6 4 ) ,  the magnitude of t h e r a t i o  i s determined to a y  D  with the possible exception different quartz, R  ol  -  thermal  ,  /  0  /  0  that  large  extent  ) , the other  o f Q, a r e a l s o i m p o r t a n t .  )/{f>:-  Given  conditions  thermal  the  (2.65)  2  a  This allows  an  estimate  i s acceptable.  losses  would  be  to  be  l o s s e s must be i n c l u d e d .  t h e s a k e o f d i s c u s s i o n , s u p p o s e t h a t an e r r o r o f  (2.65),  factors,  p) ]  made o f t h e d e n s i t y b e l o w w h i c h t h e r m a l  coefficient  by  that  may be a u s e f u l a p p r o x i m a t i o n .  absorption  although  and a c o u s t i c p r o p e r t i e s of p o l y s t y r e n e  i t would appear 1 0 - M (2 > + o  e  (A7) and  numerically.  i ti sclear  a n d t h e d e n s i t y d i f f e r e n c e ( p '-p  (y'-1)  For  absorption  l o s s e s may be  t o which t h e long-wavelength l i m i t  bound on t h e p a r t i c l e  and  relative  as i s the case f o r p o l y s t y r e n e .  relative  very  i s small. Viscous  t o t h e p o i n t where t h e r m a l  I t would appear t h a t  and  i f the bulk  Setting  R , = 0.05 i n  negligible  f o rp a r t i c l e s with d e n s i t i e s greater  5% i n t h e  than  0  under about  these 1.6  36  g  cm" . 3  The  densities  v a l u e , w i t h the and  thermal  and  (1963),  scattering  g 1~ ).  l o s s e s may  was  not  kHz,  even  the p r e s e n c e of t h e s e scatter  latter  is  shells  used  origin,  of  Finally,  p . 4 3 5 ) . The  (a)  the  high  the  s o u n d by  very  results  sphere two  (including  the  of  suspended  range.  by  Duykers  in  the  the open  biological  seem a p p r o p r i a t e be  The  to estimate  3  t o be  (2.59)-(2.60) should  in and  high. be  compared  ( 8 . 2 . 2 2 ) i n M o r s e and  s e t s of e q u a t i o n s  that  scattering  matter  of a t t e n u a t i o n may  formulae  (3.25  and  I t i s worth n o t i n g that g cm"  the  absorption  small,  discussion  2.65  of  frequency  frequency  a h i g h b u l k d e n s i t y does not  the  Watson  concentrations  much o f t h i s m a t e r i a l i s l i k e l y  such  fluid  over  this  small,  in suspensions  energy over t h i s  with  as a r e s u l t h i s e s t i m a t e s  for  attenuation  d i a t o m s must be  p a r t i c l e d e n s i t y of  viscous absorption ocean. Since  very  i n S e c t i o n 2.3.  a  be  i n d i c a t e both that thermal  little  consistent  spherical (1967)  very  should  h a v e t o be c o n s i d e r e d .  measurable  at  Their observations  1  the  a r e w e l l below  that viscous absorption  however, found t h a t  losses)  125-750  they  phytoplankton  N i t s c h i a c l o s t e r i u m f. minutissima  range  in  result  most  conduction  Meister  diatom  of  are q u i t e s i m i l a r  Ingard  with (1968,  i n form,  but  following differences:  n=0 -the -the  p r e s e n c e of ratio  of  boundary-layer  the  f a c t o r Q2c '  specific  s  heats  /3c'  2  2  ( y )  t h i c k n e s s p e r t a i n to the  t h a n t h e a m b i e n t medium.  and  the  thermal  scatterer rather  37  (b)  n=1 t e r m ( p^ -p„ )  -the  Their  expression  p<? ( p„ ' - p ) i n t h e i r  replaces  2  result.  e  f o r the viscous  part of the absorption  c r o s s - s e c t i o n d o e s , h o w e v e r , d e p e n d on ( p. '"/><,) • 2  The  Epstein-Carhart  equivalent,  however,  and  Morse-Ingard  primarily  because  c o n d i t i o n s a r e used. Morse and I n g a r d and  thermal  instead This  waves  inside  theories different  not  boundary  do n o t i n c l u d e t h e v i s c o u s  the scatterer i n t h e i r  f o r c i n g the temperature f l u c t u a t i o n s t o  approach i s u s e f u l f o r a f l u i d  are  formulation,  zero  f o r r<a.  s p h e r e i n a g a s e o u s medium,  t h e i r case i n p o i n t .  2.5  Summary Some  aspects  attenuation with  of  the  theory  of  the  o f s o u n d by s p h e r i c a l p a r t i c l e s h a v e been  t h e e m p h a s i s on s o l i d  the  problem  additional suspension  sea  a  sound  wave  parallel to (1968).  propagating  of the p a r t i c l e as w e l l as  t h e p a r t i c l e m i g h t have on m o l e c u l a r  water In  of  i s assumed t o r e s u l t f r o m h e a t c o n d u c t i o n  drag at the surface effect  s p h e r e s i n Morse and I n g a r d  attenuation  isa  i n a form s u i t a b l e t o  of a c o u s t i c b a c k s c a t t e r i n g and roughly  treatment of f l u i d  and  presented,  s c a t t e r e r s . Much o f t h e m a t e r i a l  s y n t h e s i s o f somewhat s c a t t e r e d l i t e r a t u r e the  scattering  The in  a  and v i s c o u s  scattering.  Any  relaxation losses i n  i s ignored. the  inviscid,  non-conducting  case,  the  form of t h e  s c a t t e r e d wave i s c o m p a r e d f o r d i f f e r e n t t y p e s o f s c a t t e r e r . The solution appropriate of t h a t  fora solid  to a fluid  sphere emerges as a s p e c i a l case  sphere. In the  long-wavelength  limit,  the  38  two The  solutions  are  identical  wave s c a t t e r e d by a t h i n  i n form t o terms of order  spherical  (k a) . 5  c  s h e l l , however, i s  quite  different. The  modification  effects and  Carhart  the  taken  the  s c a t t e r e d wave by v i s c o - t h e r m a l  i s e x a m i n e d . The t r e a t m e n t  of t h i s  of s o l i d  phase  angles  scatterers,  used  including  the i n v i s c i d  the  wave  scattered  e f f e c t s of these ratio  of  treatment  to  relatively  simple  with  experimental  Hawley is  a  solid  form.  viscous  This ratio  effects  that  depends  and  the r e l a t i v e primarily  particle,  is  than  the p a r t i c l e  minerals should  satisfy  This i s not l i k e l y  overall final  expression  including the  obtained  to  interest  importance  on  the  be  to this  of thermal  difference  and e l a s t i c  the in  a  consistent  thesis.  It  and v i s c o u s  in  the  bulk  In p a r t i c u l a r ,  p r o p e r t i e s of quartz 1.3 a n d 1.7  g cm  " , 3  l o s s e s c a n be i g n o r e d f o r f r e q u e n c i e s a t  which the s k i n depths of the thermal less  the  Accordingly, is  shown  p o l y s t y r e n e and d e n s i t i e s g r e a t e r t h a n thermal  terms  r e s u l t s of U r i c k (1948) and A l l e g r a and  p a r t i c l e s w i t h the thermal  respectively,  in  c a s e . The  d e n s i t i e s of t h e s c a t t e r e r and the ambient f l u i d . for  (1972) t o  explicit  absorption  (1972), and i s of p a r t i c u l a r  argued  of  non-conducting  l o s s mechanisms, i s d e r i v e d .  thermal  the  by  Epstein  ( 1 9 5 1 ) . T h i s a p p r o a c h was  r e s u l t s a r e a l s o f o r m a l l y more c o n c i s e . An for  by  i s reformulated  by F a r a n  because i t p r o v i d e s a uniform  problem,  problem  ( 1 9 5 3 ) , a s e x t e n d e d by A l l e g r a a n d H a w l e y  include the case of  of  a n d v i s c o u s waves a r e  much  r a d i u s . Most p a r t i c l e s composed o f s o l i d these c o n d i t i o n s . f o r phytoplankton,  bulk d e n s i t i e s c l o s e to that  of  sea  which i n general  water.  In  the  case  have of  39  diatoms,  the  approximated  thin-walled by  circumstances, d i a t o m s h o u l d be  a both  silica  solid the  body o f t h e same s h a p e and  spherical  energy  substantially  might  shell.  scattered  lower than that  and  be  usefully  Under  such  absorbed  by a s o l i d  by  s h e l l s has not appeared  a  silica  s i z e . A t h e o r y of the a t t e n u a t i o n  sound i n s u s p e n s i o n s of s p h e r i c a l literature.  frustule  of  i n the  40  CHAPTER 3 DETECTING SUSPENDED SEDIMENT WITH SONAR: THEORY AND Historically, quantitative ocean  t h e use o f a c o u s t i c b a c k s c a t t e r i n g  estimates  h a s been  devoted  There are s u g g e s t i o n s might  be  (1948)  reported  EXPERIMENT to  obtain  of d i s c r e t e s c a t t e r e r p o p u l a t i o n s  i n the  primarily  to  fisheries  i n the e a r l y l i t e r a t u r e  that t h i s  u s e f u l f o r the d e t e c t i o n of suspended d e t e c t i n g 0.5  mm  applications. approach  sediment.  Dietz  d i a m e t e r sand a t a f r e q u e n c y of  18 kHz a n d a t d e p t h s o f up t o 120 m a f t e r r e l e a s i n g t h e s a n d the  surface.  Hersey  and  Backus  showing  i n t e r n a l wave s i g n a t u r e s  matter  collecting  contributor sonar  front  thermocline Increased  of  (Cushing  et a l ,  deepening  in  reverberation  reported  (Trout  increased  waves  (Trout  1956)  and  reported  echograms particulate  be a  et  been  made  a l ,  internal  from  significant  tides  (Weston,  layers  and w i t h  increased  et a l ,  1956).  reverberation  same d e p t h a s t h e submerged o u t f l o w Geneva a s m e a s u r e d w i t h d r o g u e s . detected  increased  suspended  s a n d and d e t r i t u s i n an  and  1958).  with  high  Cushing  concentrations Shepard  of  1952), a  e t a l , 1952; Herdman, 1953;  d i a t o m s and d e t r i t u s (Cushing  i n Lake  might  response t o the wind  was  a l , 1956; W e s t o n , 1958)  (1963)  suggested that  pycnocline  internal  temperature gradients et  the  and  presented  t o t h e e c h o . P r e v i o u s l y , r e p o r t s had  detection  possible  in  (1962)  at  and  of Dill  from a p p r o x i m a t e l y  the  f r o m t h e Rhone R i v e r  i n Lake  S c h r o e d e r and S c h r o e d e r  (1964)  reverberation  •from a l a y e r c o n t a i n i n g i n t e r f l o w from the R i v e r  fine Toce  Maggiore.  Renewed  attempts  sounding f o r flow  have  been made r e c e n t l y t o use  visualisation  and  for detection  of  acoustic suspended  41  matter  in  detecting  the  f l o a t i n g mud  1974), dredge al,  oceans.  spoils  1978),  This  layers  water  mass  hydraulic  sludge (Proni  intrusions  No q u a n t i t a t i v e d e n s i t y were The  1973;  Gallenne,  and  Hess,  r e s u s p e n s i o n and  1978b)  and  internal  l e e waves ( F a r m e r a n d S m i t h ,  r e l a t i o n s h i p s between the s i g n a l  to  the  practical  q u a n t i t a t i v e p u r p o s e s : more turbulence  velocity  bubbles, b i o t a or may  thermocline  and  and  density  1980).  scatterer  from  scattering  layers  the  increased  mechanism particles,  different I n an  reverberation  mean  attempt  from  and  concentration  t o be a s s o c i a t e d w i t h t h e t h e r m o c l i n e , b u t  p l a n k t o n were a more l i k e l y the echoes  c a u s e . On  the  (1958) c o n c l u d e d i t m i g h t  to the increased t u r b i d i t y  of  of  problem  t h e method f o r  fluctuations,  the N o r t h Sea, Weston  known  amplitudes  one  of  c o n t r i b u t e to the r e c e i v e d s i g n a l .  in  be p a r t l y due  application  than  reflection  to d e f i n e the cause of  detritus  waves  precipitate-forming  1978a), sediment  (Orr  b o r e s and  1975),  internal  v e r y v a r i e t y o f o b s e r v e d phenomena u n d e r l i n e s a  -  with  established.  fundamental  -density  concerned  e t a l , 1976b),  Apel,  ( O r r and H e s s ,  jumps,  been  ( P r o n i e t a l , 1975,1976a and B o k u n i e w i c z e t  sewage  waste  has  (Tsuchiya et a l ,  and m i c r o s t r u c u r e ( P r o n i and chemical  work  the b a s i s of the  of that  relative  f r o m . t h e t h e r m o c l i n e and t h e s e a  he c o n c l u d e d t h a t t h e a c o u s t i c  i m p e d a n c e d i f f e r e n c e due  to  bed, the  change i n t e m p e r a t u r e a c r o s s the l a y e r c o u l d not a c c o u n t f o r the effect.  Although  d i s t i n g u i s h a b l e on (Proni  and  Apel,  some the  of  the  basis  scattering of  their  mechanisms  frequency  may  dependence  1 9 7 5 ) , no work h a s y e t been done i n w h i c h  separate c o n t r i b u t i o n s  of  both  the  physical  and  be  the  biological  42  scattering  mechanisms  have  been  determined  in circumstances  where b o t h a r e i m p o r t a n t . T h e r e h a s , o f c o u r s e , work  extensive  i n which b i o t a a r e t h e s o l e s c a t t e r e r s of i m p o r t a n c e . T h i s  i n c l u d e s most o f t h e s t u d i e s o f b a c k s c a t t e r i n g diel-migrating situ,  felt  scattering  l a y e r s and  s u c h a s t h a t by B e a m i s h The  that scattering  with zooplankton. was  from i n o r g a n i c p a r t i c l e s would dominate  the  and  tailing  kg s "  at  i s d i s c h a r g e d a t a d e p t h o f 49  as a s l u r r y  1  192 kHz  where  discharge  The  made  area  plume g e n e r a t e d by t h e s u b m a r i n e m i n e - t a i l i n g Inlet.  were  done i n an  targets in  negatively  a n d a r a t e o f 390  50% s a l t w a t e r by v o l u m e .  p r i m a r i l y o f q u a r t z and s i l i c a t e powder  1971)  o f 10% The  solids,  tailing  minerals  concentration  relationship  is  obtained,  between  and  is  s e c t i o n a l p r o f i l e of c o n c e n t r a t i o n reverberation.  s t a n d a r d t a r g e t . Other  ground  to  in diameter  This  signal  relative  other study i n which a m p l i t u d e and for  a  (Evans  amplitude  used t o g e n e r a t e a  i n t h e plume f r o m  relationship  is  the  shown  t h a n t h e work by B r a i t h w a i t e  i n which measurements were a l s o  frequency  fresh  consists  an  suspended  a n a t u r a l aqueous Section  to  3.1  obtained  at  and  crosstapeto  c o n s i s t e n t w i t h t h e o r y , and w i t h t h e a m p l i t u d e of t h e echo  rivers,  m  1976).  An e m p i r i c a l  recorded  40%  itself  (90%),  o f w h i c h 6 5 - 7 5 % i s l e s s t h a n 0.074 mm  and P o l i n g ,  a  from  i n the  Rupert  water  fish,  i t  Measurements  buoyant  from  from i n d i v i d u a l  (1969 and  work r e p o r t e d h e r e was  signal.  in  been  be from  (1974) i n a  single  a s t a n d a r d t a r g e t , t h e r e seems t o be empirical sediment  relationship  between  c o n c e n t r a t i o n h a s been  no  echo  reported  environment.  i s a s y n o p s i s of t h e t h e o r y of t h e d e t e c t i o n  of  43  suspended  sediment  wavelength  region.  experimental in  section  3.1  using In  work  conventional  section  3.2  sonar  the  the  details  long-  of  the  a r e p r e s e n t e d , and t h e r e s u l t s a r e d i s c u s s e d  3.3.  Theory  3.1.1 B a c k s c a t t e r i n g  from a S i n g l e  Scatterer  When t h e wavenumber ( k ) o f t h e i n c i d e n t t  is  in  much  smaller  than  w h i c h i s f r e e t o move,  the radius the  compression  wave  (a) of a c o m p r e s s i b l e sphere  amplitude  (p ) r  of  the  scattered  p r e s s u r e wave i s g i v e n by p, k a ( x + r c o s 8 ) e x p [ i ( k r - w t ) ] 3r ...  p =  2  r  (3.1a)  3  c  where 7=  K  X  (3.1b)  K  X, = 3 ( Pa — Po) 2  P  : + p  (3.1c)  a  In  these r e l a t i o n s ,  r i s the r a d i a l distance  the  sphere, 9 i s the s c a t t e r i n g angle, o the L  incident  pressure  wave,  ?(  the  from t h e c e n t r e of amplitude  of  the  c o m p r e s s i b i l i t y , p the  bulk  a  d e n s i t y and w t h e a n g u l a r f r e q u e n c y . Primed q u a n t i t i e s r e f e r the  scatterer.  exp[  i(k r-ut)] will  be u n d e r s t o o d .  The  (3.1a)  e  expression  Rayleigh for  In the remainder of t h i s d i s c u s s i o n ,  first  ( 1 9 4 5 , p. 283) f o r f l u i d  the  elastic  was  partial  solid  scattered  published  the factor  in  1878  by  spheres. Using the expressions  waves o b t a i n e d by F a r a n  s p h e r e s , i t was  to  shown  in  Chapter  2  (1951) f o r that  the  scattered  wave h a s t h e same f o r m f o r b o t h t y p e s o f s c a t t e r e r t o  order  5  (k a) . c  This higher  order  term  has  been  dropped  from  44  (3.1a).  The  V=  where  bulk  [ A*+2 x'/3]-  and  scatterer,  yu.'  For  Lame's  elastic  k a«1  from a C l o u d of  than  water,  considerably  that  coherent  is  cloud  of  u n i m p o r t a n t , the  denser  more  the  B o t h t h i s and  assumption that  the  is fact  can  be  multiple  i n c i d e n t sound p r e s s u r e  p  in a  scatterers is (3.3a)  0  where  and  energy  pp r Dexp(-«r- A ) r  p-=  r  A =  j *  dr  (3.3b)  for  r > > r . The  attenuation, c o e f f i c i e n t  ocj  that  to  0  from the  due  transducer  distance  a x i s t o the the  the  the  p o i n t at which the  p r e s e n c e of  The  r„  the  ambient  fluid  the  the  the  cloud  is  r, ;  r  along  the  sound p r e s s u r e  level  i s p„,  It  medium a r e  is not  and  D.  of  s u s p e n s i o n s of  been d i s c u s s e d  thermal attenuation  in dilute  i n the p r e v i o u s  chapter.  i s n e g l i g i b l e ( l e s s t h a n 5%  I t was of  D  bulk  changed  scatterers to a f f e c t sound  is  acoustic  assumed t h a t t h e sufficiently  is  distance  distance  directivity.  attenuation  s p h e r e s has  n e a r edge o f  t o the p a r t i c l e ,  p r o p e r t i e s of  i n the  s u s p e n d e d p a r t i c u l a t e i s ~x . The  to the  transducer  acoustic  that  fluid  (Y^=-0.93,  forward-scattering  U n d e r i d e a l c o n d i t i o n s and  scattering  by  a  Particles  (0=180°) t h a n f o r w a r d .  imply  c  ignored.  is  For  Table I I ) , which i s both s i g n i f i c a n t l y  s c a t t e r e d backward  the  constants.  p a r t i c l e s c o n s i s t i n g of q u a r t z - l i k e m a t e r i a l  compressible  dilute  (3.2)  ^'=0.  "^=0.77; see  that  by  1  are  Backscattering  less  i s given  /  A'  3.1.2  c o m p r e s s i b i l i t y of a s o l i d  solid shown  viscous  45  absorption)  for  greater  1.3  than  quartz.  particles g cm  s u f f i c i e n t l y high densities  for particles  - 3  A l t h o u g h t h e a n a l y s i s was  much g r e a t e r thermal  waves ( a p p r o x i m a t e l y  a l l  absorption  particle  coefficient  2^m  with  the  v a l i d only  than the wavelengths  here that v i s c o u s for  with  of at  the  200  for particle  damped  kHz),  In  this  for excess viscous absorption  be  radii  the  and  assumed  conduction  case,  losses  attenuation  i s (Urick,  1948),  6 k . (s-1 ) l 8 b ( b + 1 ) 2  s=p '/p  where  0  scatterers.  and  o  The  the v i s c o u s  The and  £  2  + b [(4s+2)b + is  the.  boundary l a y e r  i s the  9]  2  volume  parameter b i s the  b = a(w/2>/) where v  (3.4)  2  81(b+1)  2  fraction  occupied  r a t i o of p a r t i c l e  thickness  (equation  by  radius  to  2.60b)  , / 2  kinematic  shear v i s c o s i t y  attenuation coefficient  of  the  for scattering  fluid. loss  is  (Morse  Ingard,  1968, p. 435) k a (* + . « = e k 3 3  3  (3.5)  2  c  s  t  a s s u m i n g t h a t t h e m o d i f i c a t i o n of wave is  of  viscous  i t will  dominates thermal  sizes.  properties  -  by  thermal  negligible.  scattering  Because  amplitudes,  scattering The  conduction  and  these  the drag  amplitude (see  effects  (3.5)  the  scattered  previous  result  slightly  in  chapter) reduced  overestimates  the  loss. linear  dependence of  attenuation  has  s u s p e n s i o n s up  t o volume c o n c e n t r a t i o n s  with quartz  and  by  McLeroy  and  been  the  concentration  Blue  the  of  kaolinite,  established  by  Hampton  coefficient  experimentally of  9-10%  by  (1967) w i t h  (1968) w i t h a l u m i n o s i 1 i c a t e  on  i n aqueous  Urick  (1948)  kaolinite  and  (clay) pigments.  46  This  implies  that  s c a t t e r i n g o r any here and  as  an  process  involved dilute  of  (diameter  mean  95 /xm).  both confirmed  be  Since  of  was  13%  is  taken  'dilute'.  Busby  linear  up  other  1-5 /<-m,  the  extent  of  p r e d i c t e d the  the  size.  B l u e and  and  of  experiments  McLeroy  (1968)  ( 3 . 4 ) , "even f o r i r r e g u l a r Blue  to  for suspensions  the  ( 1 9 4 8 ) and  particles.  (3.4)  than  and  term  a f u n c t i o n of p a r t i c l e  the v a l i d i t y  clay  however, t h a t  of the  d i a m e t e r s of  e x p e r i m e n t s of U r i c k  platy  unimportant,  greater  particle  r a n g e may  The  is  (1956) f o u n d t h a t a t t e n u a t i o n  concentrations  g l a s s spheres  and  other  between p a r t i c l e s v i a m u l t i p l e  operational definition  Richardson  volume  interaction  McLeroy  attenuation  quartz  (1968) d i d  find,  less accurately  in  ( i n rrr ) a t  °C  s u s p e n s i o n s of n e e d l e - s h a p e d s c a t t e r e r s . The  attenuation  i s given  by  coefficient  ( C l a y and  Medwin  <X = 3.595 x 1 0" f 8  i n sea  1977,  1 Q-  S *ff  6  f2  where the  f  is  molecular  dependence small  (<  +  at €  viscous  frequency  relaxation  has the  •*T)A  various  Fig.  the  2b.  frequency  depths  (3.6) *f2  salinity  of  MgSO^ .  i n ppt The  of  quartz  Scattering F i g . 2a  considered.  density  suspended  matter  concentration  is  i s greater  distribution.  the  is  extra  than  18-260 mg  ratio  frequency  p a r t i c l e s . The  coefficients  important  *f  pressure  The  ratio  plotted  l o s s i s n e g l i g i b l e o v e r most of  shows t h a t  and  second term because i t i s  being  scattering attenuation  considered.  size  S the  +  2  i s p l o t t e d i n F i g . 2a as a f u n c t i o n of  diameters and  i n kHz,  been d r o p p e d f r o m t h e water  1.0  1  p.98)  + 2.337 x  2  water  attenuation  the  for of in  range  due  to  if  the  l " , d e p e n d i n g upon  the  (3>  0.1 << ) 1  only  47  Fig. 2 ( a ) The r a t i o o f t h e a d d i t i o n a l a t t e n u a t i o n c o e f f i c i e n t due t o s u s p e n d e d p a r t i c l e s w i t h d e n s i t y 2.65 g c m to that in sea water at 10°C with 30 ppt salinity, plotted against f r e q u e n c y as a f u n c t i o n of p a r t i c l e s i z e , per f r a c t i o n a l volume c o n c e n t r a t i o n . B o t h v i s c o u s and s c a t t e r i n g l o s s e s i n c l u d e d , (b) R a t i o of attenuation c o e f f i c i e n t s due t o s c a t t e r i n g l o s s ( x l O ) and v i s c o u s absorption. - 3  3  .  48  3.1.3  The  Sonar  Now  Equation  consider  transducer  is  the c l o u d across  used  pattern.  width  Assuming  distributed outlined squared  in  of  the  a  .large  space,  (the  the  which  number  the  of  (on  and  randomly  incoherent.  can  be  integrated  effective " back-scattered  As  combined, over  the  intensity  transducer.  transducer  (3.1)  and  of  wave b a c k - s c a t t e r e d  the  Pk= ^ _ r o D k 3r 2  2 c  a  3  2  Let  be of  an  the  angle  (3.3),  the  effective  pressure  at  (i^-v,)exp[-2.(«r + A ) ]  c h a r a c t e r i z i n g the  beam. The  detected  i s the d u r a t i o n of  is (3.7)  half-width  of  the  main  volume i s then (3.8)  2  7  the  from a s i n g l e p a r t i c l e  c r ( 2 7r)fr sin(ftdc/ where  that  antenna  scatterers  (3.3a)  2  same  average)  transducer  s c a t t e r e d waves a r e  I=p /pc)  the  r e c e i v e . Suppose  distributed  (3.1a) and  intensity  in  and  m a i n l o b e of  the  volume t o g i v e  From  lobe  system  both to t r a n s m i t  below, Equations  detected  sonar  of s c a t t e r e r s i s u n i f o r m l y  the  at the  a typical  the  transmitted pulse,  or the  'pulse  length'. Assuming a sensitive  over  1977,  144)  p. D =  circular  i t s s u r f a c e , the  the  directivity  radius  a  uniformly  i s ( C l a y and  Medwin,  Bessel  f u n c t i o n of  rms  (3.9)  0  (f> i s t h e a n g l e  The  of  2J,(k, a„ sin<£ ) k a sin^ t  where  transducer  pressure  with the level  respect first of  t o t h e a c o u s t i c a x i s and  kind.  the  return signal  becomes  J, i s  49  Pb  16ffcTk 9a  P° ° r  =  r  I'/z  3  ( r - X )exp[-2(o<r+ A ) ]BAM K  where M i s t h e mass c o n c e n t r a t i o n B=  r  J  (3.11a)  n  (k a^ s i n ^ )  3  c  narrow-beam t r a n s d u c e r s , B =_J kc o  c  (3.11b)  0  is only  over t h e main l o b e  -  s i n c ^ = <f> a n d  x=k a c& 0  .  o  The f a c t o r  2-  for  by  OO  | d n(d )dd = 0  6  (x = 3.832)  A d e p e n d s on t h e s i z e  of t h e p a r t i c l e s and i s g i v e n OO  2  becomes  x  since the i n t e g r a t i o n  A =  integral  2  a  distribution  this  [ J," ( x ) dx = B' J k a  2  which  of suspended m a t t e r and  J," ( k a sin<f>) a<t>  2  For  (3.10)  1/ 2  f  [n(a)a da 0  6  (3.12)  6  p  where dp=2a i s t h e p a r t i c l e  diameter  and  n(d )  is  p  the  size  spectral  d e n s i t y d e f i n e d s u c h t h a t t h e t o t a l number o f p a r t i c l e s  per  mass o f s e d i m e n t i s g i v e n 00  unit  N = Note  I n(d )dd 0 p  that e = a-M ^ n ( d It  is  operating the  (3.13)  p  )d dd 3  p  worth  r  noting  frequencies  particle  by  from  (3.10) t h a t w i t h A = 0 ,  y i e l d no a d d i t i o n a l  concentration  information  and s i z e d i s t r i b u t i o n  w a v e l e n g t h r e g i o n . S u c h i n f o r m a t i o n c a n be o b t a i n e d the  frequency  dependence of A  terms of h i g h e r Because frequency, range  ambient  the  c  attenuation  there  will  will  depend  noise  and  from  (<*)  through  for  increases  (3.10) and (3.11b) t h a t  be an optimum o p e r a t i n g upon  only  which  important.  coefficient  i n ^ general  regarding  i n the long-  frequencies  i n k a i n (3.1a) a r e  i t i s clear  (r)  frequency  order  , o r from  different  the  for a  given  frequency.  spectrum  with  of  This the  t h e maximum power w h i c h c a n be d e l i v e r e d t o  50  the water. pressure  The l a t t e r  depends  the  cavitation  b u t does n o t h a v e a w e l l - d e f i n e d f r e q u e n c y  Ambient  noise  levels  in  Wenz ( 1 9 6 2 ) and a t t h e h i g h kHz)  upon  will  be  dominated  t h e o c e a n have been r e v i e w e d  background  thermal  (1965) h a s shown t h a t t h e e q u i v a l e n t rms t h e r m a l for  a directional  and  i s g i v e n by p  at  =  transducer  (kT c'A aPo  frequencies  fj  1  /  such  ( >30  noise.  Kendig  noise  pressure  i s independent of frequency  (white)  (3.14)  that the wavelength.is  diameter.  T  Boltzman's  constant  and  will  a  is  the  absolute  much l e s s t h a n t h e temperature,  k  is  f i s the bandwidth of t h e t r a n s d u c e r -  i n Hz. From ( 3 . 1 0 ) a n d ( 3 . 1 1 b )  the  optimum  frequency  be t h a t f o r w h i c h t h e f a c t o r $= f e x p ( - 2 * r )  is  by  here  2  transducer  receiver  dependence.  frequencies contemplated by  threshold  a  maximum  (3.15)  since  B' i s i n d e p e n d e n t o f f r e q u e n c y .  a t t e n u a t i o n due t o s u s p e n d e d m a t t e r  The e x t r a  h a s been d r o p p e d ,  so  these  a r g u m e n t s a p p l y o n l y t o t h e n e a r edge o f t h e c l o u d . Differentiating frequency  (3.15)  f o r a thermal  with  respect  noise-limited  to  f,  t h e optimum  system i s such  that  fda = _ J _ df 2r, where r  A  frequency (3.6)  (3.16)  i s t h e maximum e x p e c t e d obtained  from  an  o p e r a t i n g range.  iterative  i s p l o t t e d as a f u n c t i o n of r^  solution  The  optimum  of (3.16) and  i n F i g u r e 3, a t 30ppt a n d  10 °C. The same d e p e n d e n c e a p p l i e s i f t h e s i g n a l n o i s e - l i m i t e d a t a l l o r i s l i m i t e d by a n y w h i t e  i s either noise  not  source-.  51  1400-1  1200H  1000^  N  800  X  *"  H  600  400  200  — i —  100  50 r  200  150  (metres )  x  Fig. 3. Optimum f r e q u e n c y f o r d e t e c t i o n o f R a y l e i g h s c a t t e r i n g v e r s u s maximum o p e r a t i n g r a n g e i n s e a w a t e r a t 10°C w i t h 30 p p t s a l i n i t y assuming thermal background n o i s e . An  estimate  obtained noise.  of  t h e minimum  detectable  from t h e e q u i v a l e n t p r e s s u r e For  thermal  noise-limited  level  signal  of  systems,  ( 3 . 1 1 b ) a n d ( 3 . 1 4 ) c a n be c o m b i n e d t o g i v e an  the  or  particles,  range.  Assuming  a  suspension  of  background  equations  (3.10),  estimate  of the  minimum d e t e c t a b l e c o n c e n t r a t i o n o f s u s p e n d e d m a t t e r size  c a n be  f o r a given  uniformly  sized  f o r which  n(dp') = o ~ ( d - d ) p  t h e minimum d e t e c t a b l e c o n c e n t r a t i o n P  2 0  ^  - r e*^ r  at  a signal-to-noise D f2  m  (3.17)  3 o.kT ,Af\ 1  2  2  ( € ) i s g i v e n by  <  ( rK  JT) B' 2  a  4TTX  2  k  2  /  d  3  r a t i o o f 1. W i t h B'=0.239  = 3.69 x 10 -  1 6  r e" r 2  2  0  c < r  (  A f ) 1 V k a :rk / d 2  t  0  3  this  reduces t o (3.18)  52  for quartz  p a r t i c l e s at  10  °C.  From ( 3 . 1 8 ) a t 30 p p t , m,  the  2.65  x  100  m  value 10  mg  6  is  pressure  of  10 /tin  1  mg  1~  per  1  2  d i a m e t e r s may  be  kHz  ms  and  a =  0.095  0  for a specific  a  of b a n d w i d t h per  estimates  Pa  of  2  of M a t o t h e r  i n F i g . 1 of  to  Orr  which  of  source  ranges  and  are  found  and  Hess  be  noted  system c o n f i g u r a t i o n . I t should  t h a t £=0.09 i s t h e maximum c o n c e n t r a t i o n  (M =  range  s c a l e d f r o m t h i s v a l u e , and  t o be c o m p a r a b l e t o t h o s e p r e s e n t e d (1978b)  0.5  diameter p a r t i c l e s at  (3.18),  ( p ) . Using  particle  T=  kHz,  t h e minimum d e t e c t a b l e mass c o n c e n t r a t i o n  l " ) of  41.7  f = 200  the  theory  applies.  3.1.4  Standard It  p  at  can  Targets  be  seen from  f=200 kHz e(  coefficient  concentration. is greater equivalent reflects given  and  T=100 m,  results The  than ,of  (3.10) t h a t  in  an  e r r o r of  a  30%  10%  of  the  It  real variability and  not  i n the  measurements. F u r t h e r m o r e ,  i t is  additional  attenuation  due  zooplankton,  b u b b l e s - can  be  One  way  attenuation the  d e p t h of  backscattered  to avoid  this  coefficient interest.  o(  of  or  the  estimate  (1965)  to  other  show  the  scatter  coefficient  uncertainties  of  by  whether t h i s  difficult to  level  attenuation  predicted  attenuation  at  a  in  the  that  the  scatterers -  fish,  neglected.  sensitivity i s t o use  The  i n the in  clear  temperature  pressure  r e v i e w e d by T h o r p e  value  is  10%  error  s c a t t e r i n the data  (3.6).  salinity  for a given  to  the  a standard  effective  from a s p h e r i c a l t a r g e t  is  of  the  t a r g e t at or  near  pressure  value  of  the  wave  53  P*= p. r„ D * a * e x p ( - 2 c < r * ) F * 2r*  (3.19)  2  2  where  a*  is  the  radius  transducer d i r e c t i v i t y the  target  1974).  form  Dividing  of  the  at the p o s i t i o n  factor  ratio  the  As  concentration  a  which  is  recorded  the  i s the  of t h e t a r g e t and  result, is  value  proportional,  voltages (3.20)  both  F*  is  Dragonette,  to  the  sound  s h o u l d a l s o be i n t h e  yields  independent  e f f i c i e n c y and r e c e i v e r s e n s i t i v i t y to  D*  ( 3 . 1 0 ) by ( 3 . 1 9 ) g i v e s  level,  pb/p*.  sphere,  ( e . g . Neubauer, Vogt and  Since the r e c e i v e r output pressure  target  an  estimate  of  of  the  transducer  a n d i s much  less  sensitive  o f °( i f r * i s c l o s e t o r . T h i s s i m p l i f i c a t i o n i s  a c h i e v e d a t the not i n c o n s i d e r a b l e c o s t of  introducing  a  D*~*  d e p e n d e n c e i n t h e e s t i m a t e o f M. Braithwaite in  rivers.  (1974) used p i n g - p o n g b a l l s a s s t a n d a r d t a r g e t s  In  the present  study  t h e y were f o u n d  d e p t h s o f 50-80 m, a n d were a b a n d o n e d carbide  spheres.  in  favour  t o implode a t of  tungsten-  The a c o u s t i c i m p e d a n c e o f t u n g s t e n - c a r b i d e i s  h i g h enough t h a t t h e b a c k s c a t t e r e d echo i s e s s e n t i a l l y rigid  sphere  a t wavenumbers o r d i a m e t e r s  below t h e f i r s ^  resonance a t k a=7 c  3.2 E x p e r i m e n t a l The  Apparatus  and  g r e a t e r than  that of a unity  and  (Neubauer e t a l , 1974).  Procedures s y s t e m was o p e r a t e d  from a 5  m l a u n c h b e l o n g i n g t o t h e UBC D e p a r t m e n t o f G e o l o g i c a l  Sciences  and  a c o u s t i c data a c q u i s i t i o n  modified  partly  f o r t h i s p r o j e c t (Appendix  2 ) . The e c h o -  54  s o u n d e r was a c o m m e r c i a l p r o t o t y p e Inc.  and  modified  for this  built  study.  by  Ross  Laboratories,  I t s characteristics  are  summarised i n Table I I I . Table  I I I . A c o u s t i c Sounder C h a r a c t e r i s t i c s  Transmitter pulse length output pulse  0.5 ms 400 V p e a k - p e a k 800 w rms  Receiver sensitivity* bandwidth  0.65 x 1 0 " V 5 kHz  Transducer impedance resonant frequency bandwidth  100 ohms 192 kHz 18 kHz  *  input which  The  s a t u r a t e s d e t e c t o r a t maximum g a i n  receiver  transducer  sensitivity,  resonant  R a d i o Type 1001-A  frequency  Standard  were  Signal  of  frequency  o f 192 k H z . The beam w i d t h points  using Equation  target.  The  return  FM  channels  analogue  of  titanate  signal  bandwidth  was  and  Generator. elements -  the  checked  trigger  in  The  angle  a  Model  echo.  3960  signal The  resonant  between  the  t o be 2.3°  flume  were  General  transducer  and has a  pulse  r e c o r d e r . The r e c o r d e d  (0-12V) o f t h e f u l l - w a v e r e c t i f i e d  and t h e  determined with a  of a H e w l e t t - P a c k a r d  tape  and  t h e m a i n l o b e - was e s t i m a t e d  (3.8). This  standard  separate  barium  gain  consists  half-power  32  6  using  a  recorded  on  four-channel  i s the envelope sounder's  time-  v a r i a b l e g a i n ramp was n o t u s e d . S i g n a l l e v e l s were m o n i t o r e d a  Tektronix  made a t a t a p e  Model  422  portable o s c i l l o s c o p e . Recordings  s p e e d oi 38.1  cm s " , 1  f o r which  the  on were  recorder  55  frequency -19  response  was  dB a t 10 kHz.  for  a  2  kHz  The  2V  flat  rms  f r o m 0-4  -3 dB a t 6.5  kHz  and  was  to  -43  dB  s i n e wave. E a c h a n a l o g u e  tape  was  tape noise l e v e l  peak-peak  c a l i b r a t e d by r e c o r d i n g t h e o u t p u t recorder's calibrator The  sampling  rate  of  5  DC  of  The  9.5  cm  s"  1  data  tapes  C e n t r e Amdahl 470 V/S  carbide  standard gauging  about  wire.  0.025 cm  spark-eroded by  12  were  mV  per  of  3m  to  time  spheres.  They  were s u s p e n d e d  cm  wire  was  weighted  The  booms  extending  cm  weighted diameter  cemented w i t h epoxy i n t o a h o l e 0.1  cm d e e p w h i c h h a d based  been  on t h a t  used  made l a b o r a t o r y d e t e r m i n a t i o n s o f s p h e r e s as  monofilament  the t r a n s d u c e r such that m.  from a  0.013  i n t o t h e s p h e r e . T h i s method was  70-75  significant  diameter  l i n e w i t h a 1m l e n g t h o f  i n d i a m e t e r and a b o u t  beneath  c o n v e r t e r . The  tungsten-  0.794  The  was  Computing  lateral  line  beam-wise  of  running to and  a was  function in  t h e t a r g e t was  position  s u s p e n s i o n c o u l d be c h a n g e d w i t h l i n e s four  used  mini-computer  least  were  The  frequency.  depth  real-time  Model I I .  N e u b a u e r e t a l ( 1 9 7 4 ) , who  suspended  by  p r o c e s s e d on t h e UBC  the b a c k s c a t t e r e d a m p l i t u d e from s i m i l a r of  a  the d i g i t i s i n g  targets  nylon monofilament nichrome  and  t a p e d r i v e s y s t e m w i t h a 12 b i t A-D  Digital  The  r a t e o f 20 kHz  D e p a r t m e n t o f O c e a n o g r a p h y PDP-12  e f f e c t i v e v o l t a g e r e s o l u t i o n was bit.  the  up t o 2046 d a t a w o r d s i n l e n g t h . D i g i t i s i n g  done on t h e UBC 9-track  from  r e c o r d e d t r i g g e r p u l s e was  a c t i v a t e a preset software delay to p o s i t i o n  and  levels  a t an e f f e c t i v e  speed  o f 5 kHz.  window w h i c h was  -40  output.  t a p e s were d i g i t i s e d  u s i n g a playback tape  kHz,  the the  turn at  point  of  tips,  fore-and-aft.  a  of  This  56  position  was  adjusted u n t i l  t h e echo  from the t a r g e t  reached  a  maximum v a l u e . Water  samples  were  c o l l e c t e d u s i n g a c o m b i n a t i o n sampler  c o n s i s t i n g of a s m a l l - v o l u m e standard was  1.2  litre  NIO  filtered  with  pre-rinsed,  filtration.  The  associated was  details  weighed  after  being  with  of  in  a  at l e a s t  means,  temperature  Together  with  cylinder),  mg  was  recorded  probably  t h e 2% e r r o r  the combined  t h a n 5% a t 10 mg launch  is  error  l " . The  moored  1  min  interval  space  was  limited  echoes  were  47  and  mm  suction  sampler  and  humidity  and  2.  Each  filtration  overnight.  w i t h a s t a n d a r d e r r o r of on  0.03  a  Mettler  H20  mg  in  difference  limit  closer  i n volume  the  o f 0.2  to  mechanical  mg  0.5-1.0  (measured  l" . 1  mg  samples  fore-and-aft.  The  were c o l l e c t e d acoustic  s e p a r a t e d each p a i r of on t h e l a u n c h , o n l y  f r o m t h e b o t t l e s and  In  l" . 1  i n t h e mass c o n c e n t r a t i o n was  water  of  with a graduate less  while  the  signals  were  each b o t t l e  cast.  recordings.  Because  3 sampling b o t t l e s  u s e d . T h e s e were p o s i t i o n e d w i t h r e s p e c t t o t h e b o t t o m the  been  size,  after  f o r s e v e r a l m i n u t e s b e f o r e and a f t e r  A 5-10  sampler  had  i n Appendix  and  a  60 °C f o r .2-3 h o u r s a n d a l l o w e d t o  determination  limit  pore  combination  and a t h e o r e t i c a l d e t e c t i o n  practice this  which  Nuclepore f i l t e r s  b a l a n c e . T h i s y i e l d s an e r r o r o f 0.04 the  on  These samples  /cm  twice before  at  room  single  water.  the  W e i g h t s w e r e d e t e r m i n e d t o 0.01 mg  bottles  0.4  mounted  from the s m a l l  system are d i s c u s s e d  oven-dried  equilibrate  using  pre-weighed  filtration  filter  into glass  laboratory  sampler  water  deionised-distilled  i n the  diameter  ml)  b o t t l e . The  drawn t h r o u g h a f u n n e l  prerinsed  (250  by  from the s a m p l i n g w e i g h t .  were using  57  Particle  size  analyses  were made on a M o d e l  C o u n t e r w i t h a 200 / t m a p e r t u r e . A known w e i g h t mg) of  of sediment a filtered  from each f i l t e r  dispersant  hexametaphosphate)  (5 g 1 ~  aqueous  i n an u l t r a s o n i c  Isoton  II  in  a  f o r 60 s i n 1 m l  solution  of  sodium  bath (Bransonic 220). T h i s  s u s p e n s i o n was made up t o 200 m l u s i n g a and  Coulter  (approximately 1  was d i s p e r s e d 1  TAII  solution  r a t i o o f 1:9 by v o l u m e .  of  glycerol  Glycerol at this  c o n c e n t r a t i o n s h o u l d reduce t h e Stokes' s e t t l i n g  velocities  q u a r t z d e n s i t y p a r t i c l e s by 2 5 - 3 0 % o f t h e i r v a l u e s i n p u r e (see  weast,  1975-1976,  p.  D-230  s t i r r e r was u s e d  that  out. A t o t a l  3.0  x  10  were  not s e t t l i n g  particles  4  corresponding  to  about  Quadruplicate  samples  precision  ±4-10%  of  were  from  counted 15-30% each  spectra  were  per of  of  to  dispersed  the  two  corrected  and  initial  filters  57.4 /<m  f o r background,  10% o f t h e t o t a l c o u n t s i n e a c h  ensure  o f 1.5 x 10" t o sample, 200 m l . yielded  a n d ±33-40% i n t h e m a s s - n o r m a l i s e d  d e n s i t i e s a t d i a m e t e r s o f 4.5  water  f o r v i s c o s i t i e s of aqueous  s o l u t i o n s o f g l y c e r o l ) . An e x t e r n a l particles  of  a  number  respectively. A l l  w h i c h amounted t o about  channel.  Probable  coincidence  e r r o r s were l e s s t h a n 5%. Samples (SEM) the  were  to verify ultrasonic  prepared  f o r scanning  electron  both the complete d i s p e r s i o n of  the  microscopy sample  in  b a t h a n d t h a t t h e l a r g e s t p a r t i c l e s were i n f a c t  b e i n g d e t e c t e d by t h e C o u l t e r  Counter.  suspension  a 47 mm d i a m e t e r 0.4/^m p o r e - s i z e  was  Nuclepore f i l t e r filter  was  washed  onto  After  dispersion,  a n d o v e n - d r i e d a t 60 °C f o r 2  h.  The  the  entire  t h e n p l a c e d on t h r e e a l u m i n u m SEM s t u b s c o a t e d w i t h  g r a p h i t e c e m e n t . A f t e r a l l o w i n g t h e cement t o  d r y , the  filter  58  was  c u t and  in  a  t r i m m e d a r o u n d e a c h s t u b . The  vacuum e v a p o r a t o r . The  under a microscope the  largest  (<20  /xm)  particle  of  1 mg)  s u r f a c e of t h e  was  removed  size  .by  were from  not  being  repeated  settling  before f i l t r a t i o n .  s u r f a c e was  a c h i e v e d with- a c e l l u l o s e  suspensions Counter  dispersion  were  t o check t h a t Fine  aspiration  of  of  prepared  interparticle  the p a r t i c l e s "acetate  in  the  on  instead  spacings. the  backing  same  the  filter filter.  fashion  of t h e same p o l y s t y r e n e b e a d s u s e d f o r  the  from  Coulter  calibration.  The coarse  distribution end  of  the  of l a r g e p a r t i c l e s Coulter  shapes of these p a r t i c l e s . present  ( F i g . 4b)  Counter  Aggregates  but  ( F i g . 4a)  confirmed  s p e c t r a . Note the of  clay-size  i n s m a l l numbers ( l e s s  spectrum.  The  degree to which  will  extent that f l o c c u l a t i o n  i n the d i s c h a r g e .  A n a l y s i s and Data  1979.  The  1979.  A  outfall  end  the measured d i s t r i b u t i o n s  t h o s e _in s i t u i s n o t known, and occurs  differ  at  the  angular  particles  than  were c o n f i n e d f o r t h e most p a r t t o t h e s m a l l d i a m e t e r  3.3  material  Thus more m a t e r i a l (4 mg  uniform  were  and  c o u l d be e x a m i n e d a t s u i t a b l e  standards  lost.  examined  s a m p l e s t o be e x a m i n e d f o r maximum  Relatively  Size  gold-coated  f i l t e r was  a t each s t a g e of t h i s p r o c e d u r e  particles  supernatant  s t u b s were  least  5%)  and  of  the  reflect to  the  Results  were c o l l e c t e d bathymetry leveed  stations  i s from a s u r v e y  submarine  t o the southwest.  a c r o s s the channel  a t two  The  channel  conducted extended  launch  axis at s t a t i o n s  ( F i g . 5)  was  1 and  during from  moored 2.  i n September,  the  August tailing  fore-and-aft  Fig.  4b.  Scanning  electron micrograph  of  t y p i c a l aggregate.  60  1  F i g . 5. B a t h y m e t r y i n A u g u s t , 1979 s h o w i n g s t a t i o n l o c a t i o n s and s o u n d i n g t r a n s e c t o c c u p i e d i n S e p t e m b e r , 1979, and I s l a n d C o p p e r M i n e (ICM) s t a t i o n A.  3.3.1  Suspended Sediment The  r e s u l t s of b o t h t h e  s i t u concentration IV.  The  values  c o e f f i c i e n t per the  and of  the A  gravimetric  determinations  s i z e a n a l y s i s are  (Eq.  u n i t mass a r e  3.12)  and  of  in  summarized i n T a b l e  the v i s c o u s  absorption  a l s o shown. T h e s e were o b t a i n e d  in  f o l l o w i n g manner. The  Coulter  Counter  channels  on  aperture  current.  diameter  at the  i n the  the  basis  assigns of  Letting  a  particle  to  a volume-proportional d;  t h r e s h o l d of t h e  be  the  equivalent  i t h channel,  2  + d.-  mass-normalized s i z e s p e c t r a l d e n s i t y at d  one  of  reduction  16 in  spherical  t h e mean d i a m e t e r  channel i s d, = d„,  The  Analysis  t  is  61  n(d~ ) =  (3.21)  £  - di where N the  i s t h e number o f p a r t i c l e s  d  channel.  Noting  volume c o n c e n t r a t i o n £ i 7TM £ N d 6 *  t h a t d „, =2  </3  £  per unit  sediment  mass  in  d , i t c a n be shown t h a t t h e L  i s approximately (3.22)  3  L  and A  = 2" M £ N-d*  2  (3.23)  6  where M i s t h e  i n situ  mass  viscous attenuation coefficient  concentration.  Similarly,  due t o s u s p e n d e d m a t t e r i s  M £ *.(d )  (3.24)  £  o? i s t h e a b s o r p t i o n  where  the  t  coefficient  per unit  mass f r o m  (3.4).  Table IV. R e s u l t s of g r a v i m e t r i c and s i z e analyses of f i l t e r e d s a m p l e s . X' i s d e f i n e d i n E q . 3.26. d is the median diameter. A** d (^m)  —  79 390  12.0 3.66 11.3 3.61  1 .07 1 .022 1.14  70.6 73. 1 74.7  280 480 870  14.3 4.88 13.4 4.69 17.4 5.99  1 .03 1 .27 1 .023 1 .048 0.99  26 27 28  86.6 89.6 91.2  220 640 1080  14.3 4.60 14.9 4.84 13.3 4.04  1.12 0.94 1.01  II  29 30 31  86.6 89.6 91 .2  380 640 800  14.3 4.65 14.2 4.94 13.3 4.39  1.01 1 .09 1 .034 1.18 1 .060  III •  32 33 34  87.6 90.7 92.2  22 190 13.7 550 14.1  Filter  Stn  Cast  1  I  21 22  70.9 73.6  II  23 24 25  I  2  * ** ***  (m)  (mg 1 - ) mg' / d o nr 'mg-" d o 1  1  5  3  1  2  1  1) 1)  M*  4.50 4.64  ***  1.17 1.21  K  1 .026 1 .031  1 .008 1 .022  62  2.5  42.5 82.5 122.5 DIHMETER(MICRONS)  162.5  F i g . 6. ( a ) H i s t o g r a m o f s i z e s p e c t r a l d e n s i t y n ( d ) a n d n ( d ) d * (+). N o t e t h a t p o i n t s b e y o n d 80>.m a r e e x t r a p o l a t e d by a s s u m i n g t h a t l o g n ( d ) v e r s u s dp r e m a i n s l i n e a r . (b) H i s t o g r a m o f n(d )c\p. The i n t e g r a l of t h i s curve i s p r o p o r t i o n a l t o t h e t o t a l v o l u m e p e r u n i t mass. P  1 0  p  P  p  63  Typical  mass-normalized  n(dp)dp  areplotted  mainly  t o the larger  d i s t r i b u t i o n s of n ( d ) , 0  i n F i g u r e s 6a a n d 6 b . B e c a u s e  l i n e a r response  the  linear  r a n g e o f t h e 200 /*m a p e r t u r e  dependence  between  log  increase  i n t h e e s t i m a t e of A through  Fig.  illustrates  7  n(d )dp p  ) 0  A i s sensitive  limit  (80 //m) o f  by  exploiting  a n d d . The l a r g e s t  this  procedure  p  p  i n the value  from f i l t e r s  CM 79/19  z Z  -  CD  CD X X  !  a  | i K  X  a '—'  1  V CD O 1  00 =  2.5 Fig.-  7. P l o t s  a -21 CD -22 -23 + -24 -25 O -26 f -27 X -28 z -29 Y -30 X -31 K -33 S -34  A  X  42.5  82.5  122.5  162.5  DIAMETER(MICRONS)  of n(dp)d  6 p  8%.  for a l l f i l t e r s .  of  A,  25 a n d 3 1 , was ± 7 %  respectively.  s;  was  i n the d i s t r i b u t i o n of  among t h e s a m p l e s . The p r e c i s i o n  A CD  and  n(d )  the v a r i a b i l i t y  b a s e d upon q u a d r u p l i c a t e s a m p l e s and ±4%,  3  p  d i a m e t e r p a r t i c l e s , t h e d i s t r i b u t i o n s have  been e x t r a p o l a t e d t o d i a m e t e r s b e y o n d t h e u p p e r the  n(d )d  See T a b l e I V .  64  3.3.2 A n a l y s i s o f A c o u s t i c A  section  of  a typical digitized  8a. I t c o r r e s p o n d s echogram  Signals.  to  reproduced  the  in  position  r e c o r d i s shown i n F i g .  indicated  w i t h in  28 p o i n t s c e n t r e d a t d e l a y s c o r r e s p o n d i n g of  the  sampling  bottles  recorded  to  the  the  first  the  echo  from  were a v e r a g e d  midpoints  over  cast at station  of  the useable  example  t i m e - s e r i e s . This i s the best data  before  on  situ concentrations,  s e c t i o n s o f e a c h r e c o r d i n g . F i g . 10 shows an 28-point-average  F  F i g . 9. F i g . 8b i s a t y p i c a l  the standard t a r g e t . For comparison  each  by  of  these  s e t , a n d was  2. B e f o r e  computing  t h e o v e r a l l a v e r a g e o f e a c h t i m e s e r i e s , p o i n t s were r e j e c t e d a t three  levels. (1) P o i n t s detector  belonging  to  echoes  which  the  (amplitude > 12V).  (2) P o i n t s b e l o n g i n g t o e c h o e s w h i c h with  saturated  fish-like  tracks  e c h o e s were i d e n t i f i e d  on on  c o u l d be  identified  t h e echogram ( F i g . 8 ) . Such a  graphic  display  of t h e  average of f i v e c o n s e c u t i v e records. (3)  28-point  averages  s t a n d a r d d e v i a t i o n s from three passes The  results  summarized and  after  signal  through  with  values  greater  t h e mean a f t e r  t h a n two  the f i r s t  thetime-series.  f o r both  the  mean  and  rms  voltages  i n T a b l e V. T a b l e V I shows t h e a v e r a g e s i g n a l applying  levels  receiver gain.  in  the these  two o f  third  rejection  criterion.  tables are a l l normalized  The  are  before mean  t o t h e same  BOTTOM  0 ~1  ;  1  1  110  120  EQUIVALENT  F i g .  (a)  8.  signal  Each  from  (pings),  or  trace  seconds  10  from  from  a  large-amplitude  (b)  Typical  Note  tape  the  the  bottom  and  of  mobile  (lower  two  recorder  panels) transient  of  data  the  tape-recorded  DEPTH  at  a  and  5  backscattered transmissions  delay  indicated, or  from  ping-pong  response  the  given  are  scatterer echoes  of  130  consecutive  20  plume  i  (ms)  average  non-overlapping sets  echoes  spheres,  is  r r  1  (T).  (depth). as  is  The that  ' f i s h ' , two  tungsten  b a l l s  (upper  carbide panel).  66  F i g . 9. E c h o g r a m s c o r r e s p o n d i n g t o F i g s . 8a a n d 10. A = p r e - c a s t recording, sounder gain=5.5; B=post-cast r e c o r d i n g , gain=5.5; C = b o t t l e s ijn s i t u , g a i n = 6; D=diel-migrating scattering layer; E=top s a m p l i n g b o t t l e ; F = ' f i s h ' i n F i g . 8 a . STN 2 PRECAST  o_  I  NBRV-28  bottom + 7 m CO  i  CD >  a  "1  r  + 3  ZD  CL.  ^Z  cr  i  i  I  I  I  I  !  i  i  i  i  i  + 2 1  —  0.  r  1  40 .  1  1  1 80.  1  1 120.  TIME(SEC)  1  160.  i 200.  Fig. 10. 2 8 - p o i n t - a v e r a g e time-series c e n t r e d a t each b o t t l e d e p t h a t s t a t i o n 2 b e f o r e c a s t I . No a v e r a g i n g over successive pings.  67  Letting  v  point-average level  s" = Xv  be  b  the average b a c k s c a t t e r e d  time-series,  define  a  voltage  in a 28-  depth-normalized  signal  where  b  X = a*r exp[2c<(r-r*) ] 2r*  (3.25)  2  Finally, s'  a  = X'.s  second  X^  matter  and X^ between  average  A  + A  are  | 3  (s') i s d e f i n e d such that  )]  the  extra  attenuation  the top ( f i r s t )  two lower b o t t l e s the  signal  where  X' = e x p [ 2 ( A  and  normalized  (second  to  suspended  sampling b o t t l e and each of the  and t h i r d ) . X^-  concentration  due  between  was  .the  determined  first  and second and  second and t h i r d samplers. The values of X are given i n Table V. R e s u l t s of d i g i t a l processing of taperecorded acoustic signals. The columns l a b e l l e d 'before' and ' a f t e r ' i n d i c a t e the s i g n a l l e v e l s before and a f t e r each c a s t . Stn  Cast  Filter  v (vc>lts) before a f t e r  1  2  X  fc  )lts)  do- )  before  2.74 2.95  2.68 3.06  5  I  21 22  2.14 2.55  * *  II  23 24 25  0.95 2.08 1 .82  3.18 2.38 2.12  2.72 3.04  1 .34 2.55 2.26  I  26 27 28  1.15 1 .49 1.81  1 .55 1 .70 1 .95  4.13 4.45 4.62  1 .46 1 .85 2.22  II  29 30 31  1 .92 1 .73 1.81  * * *  4.13 4.45 4.62  2.33 2.09 2.24  III  32 33 34  1.10 1 .07 1 .68  0.56 1 .5 1 .43  4.23 4.56 4.74  1 .45 1 .49 2.16  2.91  *No r e c o r d i n g due" t o i n s t r u m e n t a l  failure.  from  after  3.79 2.92 2.61 •  1 .91 2.09 2.37  0.81 1 .97 1 .89  68  T a b l e V, f o r r * = 71.4 m a n d was d e t e r m i n e d A  *=  from t e m p e r a t u r e  6.67 x 10 "  nr .  The  1  17, 1980, f r o m w h i c h t h e  a n d s a l i n i t y were 11.54 °C a n d 31.87  75-105 m. The v a l u e s o f X/  £  Cast  ppt  from  are given i n Table IV.  Table V I . Mean signal r e j e c t i o n c r i t e r i o n (3) Stn  latter  and s a l i n i t y p r o f i l e s a t s t a t i o n  ( F i g u r e 5) t a k e n by ICM on S e p t e m b e r  mean t e m p e r a t u r e  3  levels  Filter  v  prior  to  applying  ( v o l t:s)  before after 1  2  I  21 22  2.14 2.35  II  23 24 25  1 .04 2.19 1 .92  3.45 2.48 2.18  I  26 27 28  1 .20 1 .57 1 .89  1 .73 1 .94 2.07  II  29 30 31  2.03 1 .80 1 .85  III  32 33 34  1.17 1 .08 1 .76  0  Fig. s'(rms)  11a i s a p l o t versus  M  1 / 2  .  o f s' v e r s u s M The  i n c l u d e d , because the s i g n a l recordings.  A  straight  data  0.62 1 .60 1 .59 1 / 2  from  was h i g h l y  line  (visual  ;  F i g . 11b station  i s the signal  level  plot  1 —11  f i t ) appears  of  a r e not  non-stationary  r e a s o n a b l e r e p r e s e n t a t i o n o f t h e s e d a t a . The d a s h e d 11a  a  between to  be a  line inFig.  ( s " ) e x p e c t e d on t h e b a s i s o f  the  echo  from t h e s t a n d a r d t a r g e t .  The a m p l i t u d e o f t h i s e c h o ,  to  d e p t h a s s ' , was v*= 19.0 ± 1.2 V. The  the  same  gain  and  v a l u e of s c o r r e s p o n d i n g t o t h i s v o l t a g e i s , from  normalized  (3.25) and  69  10  — i —  20  M  1  /  2  (rngfV  30  /  2  F i g . 1 1 . (a) Normalized s i g n a l l e v e l s ' v e r s u s the" square root of the p a r t i c l e c o n c e n t r a t i o n . S o l i d l i n e i s v i s u a l b e s t - f i t t o the d a t a . Broken l i n e i s the value of s ' expected on the basis of the echo from the standard t a r g e t . (b) Plot of s (rms) v e r s u s square root of c o n c e n t r a t i o n . See s e c t i o n 3.4 f o r e x p l a n a t i o n of the broken l i n e . 1  70  ( 3 . 2 0 ) w i t h D* a n d F* s e t t o u n i t y s  "/v*  =  UcT)  1 / 2  4 k c (\~  K)B'AM  '  IS". The  dashed l i n e  of  A  Fig.  =  i n F i g . 11a i s a p l o t o f s" u s i n g a  4.63 x 10"  kg - /  1 0  1  m  2  (Table  3  theoretical  is  reasonable  signal  The  levels  offset  reverberation It  agreement at  high  between  concentration  distribution,  can  relatively  constant  o f S t a t i o n 1 —11) the  diameter  tail,  size  reflect  pressure be  expected  only  of  distributions,  in  diameter  To t h e  particularly  The  is  extent  the large  this  linearity  distribution  somewhat  size  i s t h e z o n e where  distribution  are  Because t h e b a c k s c a t t e r e d  echo  and  size  counter-  was n o t p o s s i b l e , h o w e v e r , t o s a m p l e c l o s e r  play.  approximately  the  IV (with the exception  as c o n f i r m a t i o n of the theory. A s i z e  It  root  concentration.  t h e _in s i t u d i s t r i b u t i o n ,  t r a n s p o r t m e c h a n i s m s come i n t o  amplitudes  i f  t h e shape o f t h e l a r g e  of A i n Table  1.5-2 m f r o m t h e b o t t o m , w h i c h gradients  relationship  l e v e l and t h e square  independent of d i s t a n c e above t h e bottom intuitive.  theoretical  concentration.  i s independent  values  and  i n d i c a t e t h a t s u c h was t h e c a s e .  measured  be t a k e n  empirical  (3.10) t h a t a l i n e a r  o r more p r e c i s e l y  of the d i s t r i b u t i o n ,  and  c o n c e n t r a t i o n s , and apparent  independent of p a r t i c l e  i s c l e a r - from e q u a t i o n  the  between  them c o u l d be due t o a b a c k g r o u n d  b e t w e e n t h e rms b a c k s c a t t e r e d  can  I V ) . The b r o k e n l i n e i n  There  curves.  that  value  i n S e c t i o n 5.  agreement between t h e s l o p e s o f t h e  end  mean  11b i s a p l o t o f 2S"//T7' , a n d i s d i s c u s s e d  measured  of  (3.27)  1 / 2  monochromatic phase,  the  expected,  is  the  sinusoidal magnitude  of  the  strongest  as  different  superposition  waves the  than  of  of  random  instantaneous  71  resultant amplitude and  should  Yaspan,  1968,  backscattered  pressure  such  be R a y l e i g h - d i s t r i b u t e d ( e . g .  p.  3 2 5 ) . That  s h o u l d have a  i s ,the  Gerjuoy  instantaneous  probability  density  P(p)  that P(p)dp =  1 e x p [ - p V < P > ] p dp 2<P > b  (3.28)  2  2  b  <p^  where  >  i s t h e mean-square  d i s t r i b u t i o n of the instantaneous recorded  signal  d i s t r i b u t i o n s of 1 p o i n t  centred  on  each  of  averaging  interval  shown,  the latter  distributed  probability  distributed,  the cumulative  a straight large  line.  amplitude  The  being  distribution amplitudes, can do  is  of  not  because  of  consecutive  bottles.  These  when a l l 28 p o i n t s  probability  against  s c a l e . I f the amplitudes  signals,  be s e e n f r o m F i g u r e s  amplitude  and  these  that  in  data  curves  a  Rayleigh-  were  Rayleigh-  d i s t r i b u t i o n would p l o t as i s the case  t h e tendency  increase  unexpected,  to  with  only f o r toward t h e  depth  i n the  the  Rayleigh  follow  particularly  at  small  t h e use of echo-envelope d e t e c t i o n . I t I 2 d - f , however, t h a t t h e 28-point  follow a Rayleigh distribution  amplitudes.  plotted  I t c a n be s e e n t h a t t h i s  failure  i n 399  and cumulative  Rayleigh d i s t r i b u t i o n appears t o plume.  of the  ( e . g . 399x28 p o i n t s ) a r e u s e d . B o t h t h e  p r o b a b i l i t y d e n s i t y histograms are  frequency  2 - 1 . F i g u r e s 12a-c  t h e sampling  d i s t r i b u t i o n s do n o t c h a n g e s i g n i f i c a n t l y the  The  and average amplitudes  were d e t e r m i n e d f o r s t a t i o n  are t h e amplitude records  amplitude.  which i s t r u n c a t e d . a t  means small  72  121.10 MSEC  MEAN  121.10 MSEC  MEAN  Fig. 12. A m p l i t u d e s t a t i s t i c s p l o t t e d as cumulative frequency c u r v e s (+) a g a i n s t a R a y l e i g h - d i s t r i b u t e d p r o b a b i l i t y s c a l e a n d as frequency histograms. F i g s . 12a-c a r e t h e d i s t r i b u t i o n s o f the a m p l i t u d e s i n a 28-point window centred at the delays indicated ( 2 8 x 3 9 9 p o i n t s ) . F i g s . 12d— f a r e t h e d i s t r i b u t i o n s o f the 2 8 - p o i n t a v e r a g e s (399 p o i n t s ) .  73  79/19  j—:—:—!  1.32  23 SEPT.  79  i—i—i—i—I—I—|—i—i—i—i—i—i—i—i—i—j—i—i—i—i—i—i—i—i—l—|—i—i  27.82 54.32 TIME(SEC)  80.82  F i g . 13. (a) C o n t o u r s of s i g n a l l e v e l ( i nvolts), uncorrected for spreading or attenuation. Grid points are a t the i n t e r s e c t i o n s o f h o r i z o n t a l and v e r t i c a l hash marks, and represent a v e r a g e s over 28 p o i n t s (1 m) i n t h e v e r t i c a l and 5 p o i n t s (2.5 s ) i n t h e h o r i z o n t a l . (b) Same as ( a ) , but c o n v e r t e d t o c o n c e n t r a t i o n u s i n g F i g . 11a after applying spreading and a t t e n u a t i o n c o r r e c t i o n . Contour i n t e r v a l = 5 0 0 mg 1"  74  The  e m p i r i c a l curve  concentrations  from  Fig.  signal  run a c r o s s the channel results  in  11a  levels  and  past  a r e shown i n F i g u r e s  was  used  r e c o r d e d on an station  13a and  13b,  2 and  e c h o g r a m i n F i g . 14. D a t a w e r e r e j e c t e d a t t h e levels  previously  through  a grid consisting  point  vertical  are at the  of  5-ping  The  estimate  echo-sounding  (Figure the  5).  corresponding  first  and  second  non-overlapping  h o r i z o n t a l averages. joining  the  The  hashmarks  along  p o s i t i o n of the bottom echo, chosen a u t o m a t i c a l l y last  i n t e r v a l used i n c o n s t r u c t i n g each v e r t i c a l column i n  g r i d was  28-  grid points  t h e b a s i s of a s i m p l e a l g o r i t h m , i s a l s o shown. The  point  The  c o n t o u r s were c o m p u t e r drawn  consecutive  i n t e r s e c t i o n s of l i n e s  e a c h a x i s . The on  and  mentioned.  to  that immediately  p r e c e d i n g but  not  including  the  28the  bottom  echo.  Fig. 14. Echogram c o r r e s p o n d i n g t o F i g . 13. A=tape r e c o r d e d pass, sounder gain= 5.5; B=third pass, sounder gain=€.0; C=second pass, opposite d i r e c t i o n , gain=5.5; D = d i e l - m i g r a t i n g scattering layer. P=discharge plume (channelized) X=buoyant c l o u d . See C h a p t e r 7.  75  The  concentrations  determinations  in  by d i r e c t  F i g . 13b  sampling,  was  l o c a t e d c l o s e t o the channel  of  the  high  concentration  possible that' the  high  discrimination  scatterers,  spatial  zone o v e r t h e l e f t  discussed  are  data.  due  i n F i g . 13b) i s u n d o u b t e d l y due t o concentration  the c h a n n e l ,  signal  The  gradient. force  result  Such a p r e s s u r e  associated  rightward  with  curvature  large-amplitude  statistics  apparent  from  relatively  p r o f i l e s of the c o n c e n t r a t i o n  are  increase bank  upward t o t h e l e f t a  cross-channel  flow  ( F i g . 5 ) . I f these  obtained  or the  in  (arrow  within pressure  would oppose t h e c e n t r i f u g a l  down-slope  of downslope v e l o c i t y such  in  gradient  estimates  to  side-echo.  isopleths t i l t  which would  part  d e v i a t i o n s f r o m t h e mean  The  section.  in  concentration at the g r i d point c l o s e s t to the l e f t  The  station  size distribution  two s t a n d a r d  i n 'the n e x t  any  bank. I t i s a l s o  echoes from  changes i n p a r t i c l e  were n o t r e j e c t e d f r o m t h e s e  than"  a x i s and t h e r e f o r e t o t h e r i g h t  against  that p o i n t s exceeding  higher  p o s s i b l y because t h e  concentrations  incomplete  fact  are  and  in  a  with  f o r c e s were i n b a l a n c e ,  mass  transport  instantaneous  field,  channel  provided  could  be  two-dimensional the  density  is  c o n t r o l l e d by c o n c e n t r a t i o n .  3.4 D i s c u s s i o n 3.4.1  Signal The  Statistics  apparently  linear  envelope of the full-wave of  the  mean  electrical  r e l a t i o n s h i p b e t w e e n t h e mean o f t h e  rectified  concentration  s i g n a l and  requires  further  c u r r e n t g e n e r a t e d by t h e t r a n s d u c e r  the  square-root  d i s c u s s i o n . The i s proportional  76  to  the  velocity  pressure  of  the  transducer  face and t h e r e f o r e t o the  o f t h e i n c i d e n t wave. The i n s t a n t a n e o u s  backscattered p =  wave a t t h e t r a n s d u c e r p exp(i 0  exp(-iwt)£  n  n  pressure  i sthe real  ofthe  part of  )  jn  (3.29)  j  d  w h e r e p. a n d the  are the.amplitude  n  j t h scatterer.  configuration  of  The  subscript  scatterers.  system,  t h e change  detected  volume  ( t h i c k n e s s c7/2)  pulse. over  i s coherent.  after  each ping  configuration  of p a r t i c l e s .  are  level  random  2  which  <>  =  £  The  which  the  a r g u m e n t was t a c i t l y  proportional with  the  backscattered  at a given  positions time,  realizable  assumed the  concluded  delay  by  mean  the  square  that  over  waves over the  a l l possible  i n t h ec o n f i g u r a t i o n a  sufficiently  large  c o n f i g u r a t i o n average  i s constant. assumed  inwriting  t h e mean s q u a r e  t o t h e c o n c e n t r a t i o n . The p r o b l e m  an envelope d e t e c t i o n system,  calculate  constant  pressure  average  backscattered  t h e mean c o n c e n t r a t i o n  i t was  essentially  (3.30)  approximate  This  incident  n  number provided  the  2  J  will  small  delay i s  The a v e r a g e  pings  be a v e r y  of  sense  of  ensemble a r e incoherent. of  normally  i n the  <p. >  j  denotes  configurations.  the  from  spatial  of the p a r t i c l e s  a s t h e outcome o f a  functions  a t a given 2  If  wave  back-scattering  passage  The i n s t a n t a n e o u s  i s t o be r e g a r d e d  <p > = <p > in  will  volume, and i n t h i s  wave  pressure  pulsed  <^-„ may t h e r e f o r e b e c o n s i d e r e d  the detected  scatterers  a  the  the  denotes a given  i nposition  of a wavelength during The  n  For  detection  fraction  and phase o f  the c o n f i g u r a t i o n average  (3.10),  voltage  from  should  i s , however,  t h e i n f o r m a t i o n necessaryof the squared  signal  be  that to  i s not  77  available. filtered at  5  The s i g n a l h a s been f u l l - w a v e r e c t i f i e d  t o get the envelope.  kHz i s e q u i v a l e n t  A low-pass f i l t e r  R a y l e i g h - d i s t r i b u t e d , then 2  I f , however,  the  the average pressure  means  should  pressure  that  the  rms  average  the  relationship  in  F i g . 11a. I t s h o u l d  pressure  i s g i v e n by  the  in this  e m p i r i c a l curve  voltage  and  11b i s n o t e q u i v a l e n t  v o l t a g e . The b r o k e n l i n e to  is  n o t c h a n g e t h e mean v a l u e  to  in.Fig.  many  (3.31)  proportional  (3.31)  cut-off  2  this  voltage  a  =JL<P > 4  Because low-pass f i l t e r i n g signal,  with  t o a weighted average over a great  c y c l e s o f t h e 192 kHz c a r r i e r .  <p>  and low-pass  should  explains  of a  a l s o be  the  linear  be e m p h a s i z e d t h a t t h e rms t o the  configuration  f i g u r e was o b t a i n e d  rms  by a p p l y i n g  f o r s , and r e p r e s e n t s  the l i n e  1  a b o u t w h i c h t h e t r u e rms a v e r a g e p o i n t s s h o u l d l i e . The the  following  lengths and  choice of a 28-point  was  1m was  tolerated.  averaging  considerations. necessary  the  i n t e r v a l was g o v e r n e d by  Averaging  over  several  pulse  t o reduce the v a r i a n c e of t h e e s t i m a t e ,  minimum  vertical  I n t e r e s t i n g l y , these  resolution  28-point  which  could  be  averages a r e Rayleigh-  distributed. It basic  i s worth noting that limitation  to determine region.  This  pulse  i s an  lateral  repetition  signal  statistics  impose  on t h e u s e o f a c o u s t i c b a c k s c a t t e r i n g  average  choice of o p e r a t i n g  the  scatterer  in  the  a d d i t i o n a l f a c t o r t o be c o n s i d e r e d  frequency rate  populations  and  and  range,  therefore  space s c a l e s of t h e t h e f i e l d  which  a  systems Rayleigh i n the  determine  the  t h e r e s o l v a b l e time and  of s c a t t e r e r s .  78  3.4.2  Comparison These  (1974), this for  With  r e s u l t s should  which  were  notation, r=r*,  A =0  S„-  Previous  Studies  be c o m p a r e d  presented  i n terms  the logarithm a n d D*=F*=1 l01og„Y  TS* =  Vp*  those  of  Braithwaite  of s c a t t e r i n g strength.  of the r a t i o  ultimately p  with  of  reduces  (3.10)  and  (3.19)  to  \  2 K  In  (3.32a)  5Vl  2  where <5V =  TS*  1 6-ncTr B 2  = 201og,  (3.32b)  2  (a*/2)  o  "  (3.32c)  and S =  I01og,  v  f  0  ( r -  r,,) A Mk«1 2  TS*  i s the target  detected suspended  values results  were  cannot  be  (a)  Turbulence  isothermal 10  m  through  1 MHz,  given,  so  is  strength  of the  Braithwaite's  but unfortunately direct  (1974)  neither  comparison  the  with  the our  Mechanisms  discussion is  of other  pertinent,  potential contributors  even  though  only  to  limited  made,  velocity fluctuations  Schroeder reverberation  at  scattering  volume.  bV  target,  made.  a  c a n be  the  unit  made  reverberation  statements  i s  v  Reverberation  Finally,  of the standard  S  per  o f r n o r IT w e r e  3.4.3 O t h e r  the  and  matter  measurements  9  strength  volume  (3.32d)  2  i  and a t 50  lake  Schroeder kHz  water.  from  'turbulent'  These  a g i t a t i o n with  (1964)  zones  were  reported zones  in  generated  an e l e c t r i c a l l y  driven  detecting essentially  at a depth of 3 cm  diameter  79  i m p e l l e r . The z o n e s p e r s i s t e d the  motor  suggested being  o f f , and  generated  thermometer  bubbles not can  at  that small bubbles by  were a l s o o b s e r v e d a  rose  of gas r e l e a s e d from  after  the result  of  ascent,  the  viscosity  These  diameters a r e such t h a t t h e bubbles  bubbles  with  they remain  . I t was  solution  were  rising  zones  range  1969). A lower clean  of  Although  and  the  diffusion  echo d u r a t i o n . 2  g cm"  s  1  o f 2.8-7.2 /xm u s i n g S t o k e s '  limit  surfaces  on  such  of t h e 'bubbles'  i s 1.4X10~  a bubble  (LeBlond,  diameter  of water  giving  rise  _ 1  cavitation.  by t h e s e a u t h o r s , t h e d i a m e t e r s  °C,  switching  t h e passage of s c h o o l s of f i s h ,  c a n be c o m p a r e d w i t h t h e o b s e r v e d 7  after  r a t e s o f 0.03-0.2 m s  be e s t i m a t e d f r o m t h e r a t e s o f  At  s  the t u r b u l e n c e . Since s i m i l a r  are not n e c e s s a r i l y  lifetimes  140  d u r i n g t h e s t e p - w i s e r a i s i n g and l o w e r i n g  and  attempted  f o r about  - 1  ,  law.  should s h r i n k as they  the  lifetimes  (T ) L  of  c a n be o b t a i n e d by a s s u m i n g t h a t  a t t h e same d e p t h . U s i n g  equation  (5)  in  Leblond  (1969), the e x p r e s s i o n f o r the l i f e t i m e i s (3.33a)  (3.33b) D  c  is  the  molecular  concentration  diffusivity  i s C i n the bubble  Leblond  (1969),  internal  pressure, c l e a n bubbles  could  not  consistent  last with  reverberation due  C'=  K/2  f o r more the  and  than  of  and C C=KP  the  gas  and  i n the water. where  P  interpretation  s that  at  Following  i s the bubble's  of oxygen w i t h t h e s e 80-130  i t s mass  diameters  10  m. T h i s i s  the  increased  i n t h e wake o f t h e i m p e l l e r o r a m o v i n g o b j e c t was  t o the formation of bubbles.  80  Schroeder some of t h e Sound  and  Schroeder  ( 1 9 6 4 ) a l s o seem t o s u g g e s t  backscattering could  scattering  from  homogeneous f l u i d  has  the  be  turbulence  been t r e a t e d i t was  from v e l o c i t y  (1953),  h o w e v e r , and  vanished  at s c a t t e r i n g a n g l e s of  fluctuations.  velocity  field  theoretically  found t h a t the  that  by  in  a  Kraichnan  s c a t t e r i n g amplitude  180°.  (b) T u r b u l e n c e d e n s i t y f l u c t u a t i o n s Turbulence f l u c t u a t i o n s i n the d e n s i t y cause  backscattering.  a m p l i t u d e s of particle the  the  Without  fluctuations  concentration,  magnitudes  of  inhomogeneities. reverberation  direct  it  in  wave  can  of  the  temperature  and  seem p o s s i b l e t o  backscattered  T h i s m e c h a n i s m may  s u g g e s t e d by F i g .  however,  measurements  salinity,  does not  the  field,  estimate  from  c o n t r i b u t e to the  such  background  11.  (c) R e f l e c t i o n from d e n s i t y d i s c o n t i n u i t i e s Although of the and the  temperatures  s a m p l i n g program d e s c r i b e d  M from a p r e v i o u s  c r u i s e are  echogram. Sharp g r a d i e n t s  determined  from  discrete  consistently  given  the  profiles  of  and  the  impression.  These  gravitationally alone,  prevent  vertical  abrupt break it  of  suspended  that  the  h e r e , t y p i c a l p r o f i l e s of  T,S  shown i n F i g . 15 t o g e t h e r  with  with  properties  but  the  that  respect  There  i s n e v e r r e f l e c t e d i n any  echograms  sediment tend  is  have  to confirm  this  plume  is  temperature  and  are  often  required e v i d e n c e of  S p r o f i l e s w i t h i n the o b v i o u s way  be  interface,  the  to  suspended .solids  i n t h e T and  cannot  of a d i f f u s e upper  indicate  convection.  i n slope  part  samples,  profiles  and  m e a s u r e d r o u t i n e l y as  scalar  impression  unstable  salinity  but  were n o t  on  the  to an  plume,  echograms.  81  F u r t h e r m o r e , u s i n g t h e same a r g u m e n t s a s Weston  (1958), but w i t h  t h e s t a n d a r d t a r g e t a s an a m p l i t u d e r e f e r e n c e , r e f l e c t i o n s s u c h an i n t e r f a c e  s h o u l d n o t be a s i g n i f i c a n t  b a c k s c a t t e r e d energy. (1956)  and  B  •s.  11.4 I  31.8 I  high  as  9.5°C n r ) 1  11.6  n.a TEMP ( ° C )  32.0  32.1  S  (%o)  **y  RUP 26* 13 Sept. 1978  I  (as  received.  11.2  11.0 50-  (1964) h a v e r e p o r t e d l a y e r s  temperature g r a d i e n t s  f r o m w h i c h no e c h o was  contributor t o the  I t s h o u l d be n o t e d t h a t b o t h C u s h i n g e t a l  Schroeder and Schroeder  w i t h pronounced  from  A  r-  0. Ill  a  \ ii<H  10  20  >  — I — 100  SO  TSP (mg/l)  F i g . 15. T y p i c a l T, S a n d M (TSP) p r o f i l e s plume ( s e e a l s o C h a p t e r 7 ) .  through the discharge  (d) Gas b u b b l e s In  1975  t h e mine c h a n g e d t h e i r  t r a p a i r b u b b l e s w h i c h were e n t r a i n e d had  previously  resulted  i n the  slurry  i n some o f t h e t a i l i n g  the s u r f a c e w i t h the r i s i n g these  discharge configuration to and  which  being c a r r i e d to  bubbles. I t i s u n l i k e l y  that a l l of  b u b b l e s a r e removed b e f o r e d i s c h a r g e w i t h t h e new  a l t h o u g h t h e r e i s no l o n g e r any s u r f a c e m a n i f e s t a t i o n  of  system, their  82  existence.  Bubbles,  especially (  10  t h e case because  at  4  t h e n , must be o f some c o n c e r n , a n d t h i s i s  the  i n equation  s u r f a c e ) compared t o t h a t  t h a t even non-resonant light  \  (3.1)  is  so  high  f o r mineral particles  bubbles a r e extremely important.  In  the  o f t h e d i s c u s s i o n c o n c e r n i n g e q u a t i o n ( 3 . 3 3 ) , h o w e v e r , any  bubbles  which  do  not r i s e  f a s t enough t o escape  t h e plume a r e  unlikely  t o s u r v i v e t o d e p t h s o f 90 m a t a d i s t a n c e o f  0.75  km  from t h e p o i n t of d i s c h a r g e ( F i g . 5 ) . (e)  Biota It  taken  i s o b v i o u s from t h e a c o u s t i c while  a t anchor  records, p a r t i c u l a r l y  ( e . g . F i g . 9, t h a t t h e r e a r e s i g n i f i c a n t  numbers o f m o b i l e l a r g e - a m p l i t u d e s c a t t e r e r s w i t h i n It  i s quite l i k e l y  enough do  to  that these s c a t t e r e r s are f i s h .  pattern  (e.g. F i g . 8).  sensitive  Those  on  p a t t e r n c a n n o t be i d e n t i f i e d a n d a r e a error  is  not f e l t  t o be s i g n i f i c a n t  low c o n c e n t r a t i o n o f s u c h echo-sounding (f)  the  plume.  They a r e e a s y  d i s t i n g u i s h and t o e l i m i n a t e , h o w e v e r , p r o v i d e d t h e y  i n f a c t pass through a s u f f i c i e n t l y  beam  those  runs  of  on a v e r a g e , as  of  error.  This  i n view of the  determined  from  the  (e.g. F i g . 14).  Floccules It  Assuming than  9%  is  likely  that  floccules  form i n t h e d i s c h a r g e plume.  the c o n c e n t r a t i o n of p a r t i c l e s by  volume,  the p a r t i c l e s  in a  floccule  is  t h e y were u n i f o r m l y d i s p e r s e d  less  s h o u l d behave as independent  s c a t t e r e r s , a n d w o u l d c o n t r i b u t e no more t o t h e r e t u r n e c h o if  the  the p e r i p h e r y of the  source  scatterers  part  than  t h r o u g h t h e d e t e c t e d volume.  83  CHAPTER 4 THE MORPHOLOGY OF TOE T A I L I N G The b a t h y m e t r y three  succeeding  of t h e t a i l i n g times  d e p o s i t o f f t h e mine s i t e  i s shown i n F i g . 16. T h e s e s u r v e y s  the e v o l u t i o n of the d e p o s i t over a state  i n which  morphological of  In and  t h i s chapter  seismic reflection  deep-sea  Continuous  surveys are presented.  of the channels  or 'apron',  to  Seismic  was  morphological  a r e compared t o t h o s e of r i v e r s  first  reflection  and  S c i e n c e s and t h e then mine's  also present  in  before  evidence  absence of a t r a n s e c t  discharge  from  the o u t f a l l .  the  north  a  1971  of G e o l o g i c a l as  part was  (1974) has d i s c u s s e d t h e a  channel. had  reveals  slope  The  1971  begun, but a r e -  of a c h a n n e l , p r i n c i p a l l y along  from  m o n i t o r i n g program. A channel  o f t h e 1972 a n d 1973 p r o f i l e s  inconclusive  in  ( F i g . 17).  o f O c e a n o g r a p h y a t UBC  t h r e e s u r v e y s and does not m e n t i o n conducted  1974  annually  by t h e D e p t .  i n 1975 ( F i g . 1 8 ) . J o h n s o n  was  in  (CSP) s u r v e y  conducted 1977  Institute  environmental  observed  Profiling  again  1975  examination  The  bathymetric  Surveys  through  distance  reach  fan-valleys.  in a series  survey  a  on t h e w e s t f l a n k o f t h e a p r o n i n  T h i s was t h e f o u r t h  first  from  t h e upper  t h e r e s u l t s of these and o t h e r  The s u b m a r i n e c h a n n e l  the  show  survey.  4.1 The R e s u l t s o f E a r 1 i e r  of  at  was t h e d o m i n a n t  was r e p l a c e d by "a s u b m a r i n e d e l t a  characteristics and  period  a regime i n which  the redevelopment of a channel the l a s t  three-year  a l e v e e d and meandering c h a n n e l  f e a t u r e , through  the channel  DEPOSIT  positive  but  because of the at  a  suitable  84  Fig. 16. Time series of b a t h y m e t r i c surveys showing ( a ) , the meandering c h a n n e l regime i n . November 1976, ( b ) , the apron regime i n September 1978 a n d ( c ) , t h e r e c h a n n e l i z e d r e g i m e i n A u g u s t 1979. C o n t o u r s i n m.  Fig.  18. T a i l i n g  thickness  i n m e t e r s , 21 O c t o b e r ,  1975.  86  Fig. 19. Pre-mine bathymetry seismic reflection lines (CSP) l i n e s (ICM) are a l s o shown.  In The  1975  the  mine  approximate  together  with  superimposed  those on  summarized  in  Table  relative  of  the  locations  of  running  locations  approximate  basis  began  in and  of  channels  VII.  relief  and  The  lines  are  seismic  pre-mine  of  echo-sounding  these  the  Rupert Inlet. the mine's  main  in  reflection  in  channel  cross-sectional  lines  shown  bathymetry. observed  Locations of echo-sounding  The each  was  monthly. F i g .  surveys, number  and  profile  are  selected  area.  19,  on  the  87  T a b l e V I I a . Summary o f t h e number o f c h a n n e l s observed in surveys. The l e t t e r s N and S i n d i c a t e t h a t t h e main c h a n n e l c l o s e t o t h e n o r t h or s o u t h w a l l of the i n l e t . Date Sept Nov Oct Jan  73 74 75 77  8A  8  9  10  1 1  11A  12  13  14  * *  1 1 1 1  2 1 1  1 1 1 1  3 1 2 1  * * 2 1N  0 1N 2 1N  0 IN • 1N 1N  0 1N 0 0  1 1  * l i n e not  1  run  T a b l e V I l b . Summary o f t h e number o f c h a n n e l s observed in f i r s t 20 ICM s u r v e y s . N = n o r t h s i d e ; S = s o u t h s i d e ; C = c e n t r e . Date 8 Mar 18 Mar 2 May 23 J u n 16 J u l 1 3 Aug 22 S e p t 28 O c t 17 Nov 1 5 Dec 1 5. J a n 12 Feb 12 Mar 9 Apr 18 May 22 J u n 27 J u l 27 Aug 28 S e p t 4 Nov In  75 75 75 75 75 75 75 75 75 75 76 76 76 76 76 76 76 76 76 76  8  10  1 1  1 1 1  2 2 1N  2N 2N 3N 3N 3 3 3 1N 1N 1N 0 1N 0 1N IN 1N 1N  1 1 1  2S 2 2 2 2S 2 2N 2 2 2N 1N 0  1  1 1  1 1 1  1 1  12  13 1N 1N  1 0 0 0 0 0 1N  1N IS  0 0 1 0 1 2  1N 1N 2C 2C  14  1S 1S 1  (1)  15  IS  both  the  is 1S  1 1  0 0  1 1 1 1 1 1  1  1 1 1 1 1S 0 0 0  >  1C 1 0  general,  channel r e l i e f  the  16  1 1  a r e a d e c r e a s e w i t h d i s t a n c e d o w n s t r e a m . The also  CSP was  IS  0 and  cross-sectional  following points  are  noteworthy. A c h a n n e l was  Bottom  scouring  responsible  never o b s e r v e d a t or beyond CSP-18 or by  tidal  f o r the f a i l u r e  a r e a , and w i l l  currents  ICM-17.  i s probably at l e a s t  of the c h a n n e l t o b u i l d beyond  be d i s c u s s e d i n d e t a i l  elsewhere.  partly this  88  (2)  Along  profiles was  the  section  of  the  8A, 8, 9 a n d 10, a n d a t ICM-8, more  observed  (3)  cross-inlet  Two  o n l y o n c e (CSP 9, S e p t .  or  channel,  than  one  a t CSP channel  1973).  more c h a n n e l s were o b s e r v e d a t a n d d o w n - i n l e t o f  CSP-10 i n 1975, a n d on many o c c a s i o n s a t a n d b e y o n d ICM-10. number a n d l o c a t i o n o f t h e c h a n n e l s 4.2 B a t h y m e t r i c a n d S e i s m i c The  channel  The  i n t h i s area are v a r i a b l e .  Surveys  was a c c u r a t e l y  surveyed  f o r the f i r s t  time i n  November, 1976 ( F i g . 20) u s i n g a D e l N o r t e M o d e l 202A T r i s p o n d e r range-range  positioning  each  a n d ±3 m i n t h e p o s i t i o n . The t r a n s p o n d e r s i t e s  range  system  w i t h a r a t e d a c c u r a c y o f ±1 m  s u r v e y e d by t r i a n g u l a t i o n w i t h a W i l d T2 t h e o d o l i t e ,  established  two  new  benchmarks  c o o r d i n a t e s of the transponder The  for this  a t s i t e C ( F i g . 20) a n d a d j u s t i n g t h e r a n g e at  sites  v a l u e s . The p o s i t i o n  documented i n Appendix Soundings  were  to t i d a l  datum  using  tidal  Hydrographic  Service  speed  The  f o r t h i s and subsequent  from  depths  of sound.  the  triangulated surveys  are  3. made  f r o m t h e CSS V e c t o r a t s p e e d s o f 4-6 echo-sounder  200 kHz, b e a m - w i d t h 5° x 1 0 ° ) . D e p t h s were  consecutive  different  study.  readings  k n o t s w i t h a R o s s L a b o r a t o r i e s M o d e l 200 F i n e L i n e (frequency  ICM  t h e b a s e u n i t up  A a n d B ( F i g . 20) t o t h e i r  fixes  The  s i t e s a r e known t o w i t h i n +0.5 m.  T r i s p o n d e r s y s t e m was c a l i b r a t e d by s e t t i n g  transponders  were  readable to  1 s o f a r c , f r o m b e n c h m a r k s i n t h e ICM s u r v e y i n g g r i d . staff  on  a  cosine-interpolation  extrema (1976).  as A  predicted reflector  to •obtain a correction  This procedure  by was  corrected  scheme  between  the  Canadian  lowered  forvariations  was a b a n d o n e d i n l a t e r  to  in- the  surveys i n  89  w h i c h t h e maps were c o n s t r u c t e d correction.  The  correction  i n the f i e l d  f a c t o r was  e a c h c r u i s e a s t h e r a t i o c ' / c , where c s  for  s  which the echo-sounders  of  T i s the time  100 m,  and was  profiles  using  ( i n seconds)  with  determined subsequent  to  i s the  s  100m.  sounding  speed  (1463 m s * )  and c j  1  The  f o r sound  latter  bathymetric  (Fig.21)  reflection  from  positioning made use  map.  s u r v e y was  purse-seiner  system. I n t e r p r e t a t i o n  of  discussed  the  previous  in  detail  s e i s m i c equipment  surveys in  Hay,  The  had  sensitivity  is  1 kHz, a  Walter  (e.g.  January  1977  using  Figs.  Macdonald  17  the  o f 0.4  calculated  f o r m u l a e i n T u c k e r and G a z e y  18),  as  (1978).  The  236 boomer and a m  single  intervals.  - 2 kHz. The  from  same  thickness  and  and M u r r a y  s p a c e d a t 0.30  the  The  angular  appropriate  ( 1 9 6 6 , p.172  t h e o u t g o i n g p u l s e f r o m t h e boomer ( d i a m e t e r  and  181).  0.41  h e m i s p h e r i c a l wave o f n e a r l y u n i f o r m a m p l i t u d e ( o n l y  dB a t 73°  from the  vertical).  uniformly  sensitive  i n any d i r e c t i o n  its  line  m. in  M.,  is  at  i n terms of t a i l i n g  nominal band-width  o f t h e s y s t e m was  theoretical At  a  i n C l a y and  depths  conducted  i n c l u d e d an EG&G M o d e l  l i n e a r a r r a y o f 25 h y d r o p h o n e s receiver  salinity  appropriate normalization equation  i n t e r s e c t i o n s u s u a l l y d i f f e r e d by l e s s t h a n 0.2 A seismic  100/T,  to a depth  and  the e q u a t i o n f o r t h e speed of sound  each  is  to t r a v e l  d e t e r m i n e d from the temperature  Medwin ( 1 9 7 7 , p. 8 8 ) . The given  a  were c a l i b r a t e d  i s t h e s o u n d i n g speed t o a d e p t h of where  without applying  axis.  parallel  The  main  t o i t s a x i s of  the v i r t u a l l y  lobe 10°  of  A  linear  hydrophone  array  in a plane perpendicular  -0.7 is to  t h e a r r a y has a p r e d i c t e d w i d t h  b e t w e e n t h e -3 dB p o i n t s . B e c a u s e  uniform angular  m)  distribution  of  energy  in  of the  90  outgoing  pulse,  this  system  i s particularly  echo from bottom and sub-bottom displaced  features  which  to side-  are  laterally  from t h e p a t h of t h e s h i p .  A s i d e - s c a n s u r v e y was c o n d u c t e d Richardson  using  a  Klein  i n June,  1977 f r o m t h e CSS  M o d e l 401 s i d e - s c a n s o n a r  0.1 ms p u l s e l e n g t h ) . The t r a n s d u c e r s 402)  sensitive  on  the  (100 kHz,  tow-fish  (Model  h a v e h o r i z o n t a l b e a m - w i d t h s o f 1° a n d a 40° v e r t i c a l  w i d t h . The a x i s o f t h e main l o b e o f t h e beam i s below  the  horizontal.  tilted  beam-  at  i s shown i n F i g . 22.  A s u r v e y was c o n d u c t e d on December 2 3 , 1977 ( F i g . 23) Mac  I  (ICM)  u s i n g a Furuno  echo-sounder  assuming is  just  in  results  are  F i g . 2 3 . The p o s i t i o n s were c o r r e c t e d a s shown by  constant vessel v e l o c i t y , with the r e s u l t a  from  w i t h a 30° beam-  w i d t h a n d r a d a r r a n g e - a n d - b e a r i n g p o s i t i o n i n g . The presented  30°  P o s i t i o n s were f i x e d u s i n g r a d a r - r a n g i n g  t o s h o r e l o c a t i o n s . The s i d e - s c a n r e c o r d  the  ;  qualitative  illustration  that  F i g . 23  of the bathymetry a t t h e  t i m e . The c h a n n e l p r o f i l e s a r e shown i n F i g . 24. A pronounced  l e v e e d submarine  c h a n n e l was p r e s e n t  of t h e s e s u r v e y s . F u r t h e r m o r e , a s e r i e s o f w e l l - d e f i n e d was  observed  the c r o s s - i n l e t  in  that  the  December,'  latter  1977  was t h e l a s t  f i x e s were n o t s u f f i c i e n t l y survey  survey i n  c h a n n e l s y s t e m was o b s e r v e d .  CSP  each  meanders  s e c t i o n of the channel immediately  r e a c h , e x c e p t i n g t h e 1974 a n d 1975  for which the p o s i t i o n  in  below  surveys  a c c u r a t e , and  w h i c h d i d n o t c o v e r t h i s a r e a . The which  the  upper  reach  of  the  91  Fig. 20. B a t h y m e t r y i n November, 1976. To o b t a i n ' t r u e ' d e p t h s ( z ' ) f r o m d e p t h s i n d i c a t e d ( z ) , z' = [ ( z - 3 . 7 ) / l . 031 ]c ' / c where c ' = 1483.4 m s~ i s t h e s o u n d i n g s p e e d t o 100 m d e p t h . The h e a v y l i n e indicates the channel a x i s . s  1  s  Fig.  21. T a i l i n g t h i c k n e s s  i n meters,  12 J a n u a r y , 1977.  92  CO  CO  F i g . 22. S i d e - s c a n s o n a r r e c o r d , J u n e 1977. The numbers 1-6 identify the axes of the s i x c o n s e c u t i v e bends; the v e r t i c a l l i n e s i n d i c a t e r a d a r f i x e s ; S and B the s u r f a c e and bottom echoes and 0 z e r o r a n g e on e a c h c h a n n e l . The u p p e r h a l f o f e a c h panel i s the record from the s t a r b o a r d transducer; the lower h a l f t h a t f r o m t h e p o r t . (See a l s o F i g . 2 9 ) .  Fig.  23.  circles  (a)  Vessel  p o s i t i o n s f o r December,  are adjusted  i s a l s o shown  (dashed  positions, line).  (b)  1977 s u r v e y .  Bathymetry  S o l i d t r i a n g l e s are  in December,  radar  1977. A x i s o f November,  fixes;  solid  1976 c h a n n e l vo oo  94  F i g . 24. December 1977 c r o s s - c h a n n e l profiles, c h a n n e l , a t l o c a t i o n s g i v e n i n F i g . 23.  looking  down-  95  4.3 M e a n d e r i n g C h a n n e l Regime The function in  depth  of  the  of distance  Figure  25.  channel  (along  Note t h a t  axis  the axis) this axis  in  from t h e o u t f a l l i s the locus  d e p t h o f t h e c h a n n e l on e a c h s o u n d i n g necessarily  coincide  with  the  -  because  maximum c h a n n e l d e p t h s perpendicular The  traverse,  1976 a s a is  shown  o f t h e maximum and  does  not  channel thalweg - the locus of the  profiles  are  not  a l l  to the thalweg.  channel  henceforth  November,  called  may be d i v i d e d reaches,  slope:  the  cross-inlet  section  (middle reach),  each  section  i n t o three  of" successively (upper  and t h e r e l a t i v e l y  Each reach e x h i b i t e d d i s t i n c t m o r p h o l o g i c a l 40  Axes of Bends  ,§  6 0  AXIAL DISTANCE  F i g . 2 5 . D e p t h o f November, long-channel distance.  principal  reach),  sections, decreasing  the  s t r a i g h t lower  meander reach.  features.  -i  "  (km)  1976 c h a n n e l a x i s a s a  function  of  96  4.3.1  Upper Reach The  bottom  slope in t h i s  9.5°-12° a t t h e o u t f a l l Fig.  25).  t o 1.9°  Cross-channel  section  ranged  a t t h e end  profiles,  from  an  estimated  of the r e a c h  looking  down-channel,  shown i n F i g . 2 6 a . T h e s e p r o f i l e s were c h o s e n b e c a u s e n e a r l y p e r p e n d i c u l a r to the channel lower  three  fourths  asymmetry, the r i g h t in  the c e n t r a l  turn  left  submarine  channel  axis  ( F i g . 20 and  in this  the higher r i g h t  channels  are  ( F i g . 2 7 ) . Those i n t h e left-right  s e c t i o n of the r e a c h b e f o r e the c h a n n e l 27)  left  begins  has a  levee  -  are  characteristic  currents  in  response  discussion will right  found  from that  channel  possibly  in  the  1977  t o the C o r i o l i s  t o be  and  hydraulic  later.  of  The  survey  subsequently. ( F i g . 24).  right  turbidity  bank  the l e f t ,  study  first  to entrainment jump.  of  f o r c e (Menard, 1955).  s t e e p e r than  w i d t h between t h e  i s p r o b a b l y due a  surface  by  Note  and  of  with  Davis  l e v e e s were m a r g i n a l l y s t a b l e . The  section decreases by t h e  upper  25°-30°. A s l o p e - s t a b i l i t y  relief  F i g . 26a  the  return to this point  levee a l s o tends  ranging  of  the  hemisphere,  h a v e been a t t r i b u t e d t o p r e f e r e n t i a l d e p o s i t i o n on t h e t o the t i l t i n g  to  slight  r e a c h . These f e a t u r e s -  on d e e p - s e a f a n s i n t h e n o r t h e r n  l e v e e due  in  they  the r e a c h e x h i b i t a marked  t o hook t o t h e l e f t  hook and  are  levee being g e n e r a l l y h i g h e r than the  d o w n - i n l e t . The  tendency  and  of  axis  (inset,  The the  slopes (1978)  increase in  second  profiles  o f a m b i e n t sea  water,  t h a t the channel  cross-  T h i s f e a t u r e was  also  exhibited  F i g . 2 6 . C r o s s - c h a n n e l p r o f i l e s , l o o k i n g d o w n - c h a n n e l , November r e a c h ( c ) l o w e r r e a c h (d) meander r e a c h a t c h a n n e l c r o s s - o v e r s .  1 9 7 6 . (a) u p p e r See F i g . 27 f o r  r e a c h (b) m i d d l e locations.  VO  98  Fig.  27.  Sounding t r a n s e c t s  for p r o f i l e s in F i g .  Seismic p r o f i l e s across t h i s thick  bed  underlying of The  the  of the  truncated channel a x i s .  and  reach  ( F i g . 28)  laterally  In c o n t r a s t ,  26.  coherent the  from  the  d e p r e s s e d b e n e a t h the d u r i n g the  initial  pre-mine  sediment-water  l e v e e s , p r o b a b l y as  p h a s e s of  a  channelization.  structure structures.  interface  result  a  reflectors  internal  levees comprises i n c l i n e d , weakly r e f l e c t i n g  echo  indicate  of  (P)  is  erosion  99  a.  Fig. 28. S e i s m i c reflection profiles across upper (a) A x i a l L i n e 2, 1977, (b) A x i a l L i n e 2, 1975. See F i g s . and 21 f o r l i n e l o c a t i o n s .  4.3.2 M i d d l e - R e a c h :  t h e Meanders  The b o t t o m s l o p e t h r o u g h 0.91°  ( F i g . 25), although The  (Figs. radar shape  meanders  were  this  reach  i s nearly  constant  i t decreases  b e t w e e n b e n d s 5 and 6.  present  three  20-22) a n d , a l l o w i n g fixes  reach: 18, 19  in  successive  f o r the large probable  f o r the side-scan l i n e ,  of t h e meanders from s u r v e y  the i n t e g r i t y to survey  2 9 ) . The number o f c h a n n e l - c r o s s i n g s  error  at  surveys in  the  of the g e n e r a l  i s remarkable ( F i g .  i n t h e 1977 CSP s u r v e y  was  100  not  sufficient  Instead,  t h e a x i s was  which the of  NE  to a l l o w the channel  t r a c e d from the  i s o p a c h map  i s w e l l d e f i n e d . The  from the of  side-scan  record  ( F i g . 29b)  i t s t r u e p o s i t i o n as per  assumed  behind  the  It  t o be due  to the  the  radar  1979)  features survey,  for  levees 116  f i x e s . This  channel  m  to  offset  profiles,  (unknown) d i s t a n c e o f t h e  in subaerial rivers. A  and  tow-fish  at  the  in Fig.  are  s u c h as  be  of  at  the  channel  outer  sketch  showing  i n F i g . 25,  partially side-echo.  in cross-  masked  but by  cross-overs  (concave)  ( e . g . L e l i a v s k y , 1966  suggested  may  meanders  30.  shoals  base  of bend axes  the  o f a r i v e r meander i n p l a n and  characteristic  deepening  al,  features  i s presented  The  vicinity  is offset  i s i n s t r u c t i v e t o e x a m i n e t h e "morphology of  salient  section  ( F i g . 21),  ship.  i n comparison w i t h those the  drawn.  p l a n p o s i t i o n of the  g a v e t h e c l o s e s t s u p e r p o s i t i o n o f t h e two is  a x i s t o be  i n f l u e n c e of o f f - a x i s p o i n t s i s such t h a t the p o s i t i o n  the channel  obtained the  in i t s e l f  p.103;  a r e not  and  bank i n  the  Dietrich  et  pronounced.  e r r o r s inherent  in  Such the  101  Outfall  a) November 1976 January 1977  400  400  800  Scale in metres b) November 1976 January 1977 (side scan)  F i g . 29. (a) Channel axes i n J a n u a r y , 1977 ( s o l i d l i n e ) and November, 1976 ( d a s h e d line). ( b ) C h a n n e l a x i s i n J u n e , 1977 ( s o l i d l i n e s ) a n d November, 1976 ( d a s h e d l i n e ) . N o t e o f f s e t of side-scan p r o f i l e due t o s h i p t o t o w - f i s h s e p a r a t i o n . ( S e e a l s o F i g . 22)  102  Cross-sectional profiles  from t r a v e r s e s c l o s e s t  a x e s a r e shown i n F i g . 26b. O v e r s p i l l on bend  resulting  from t h e i n e r t i a  asymmetry o f t h e p r o f i l e s . levee higher  and  458).  in terrestrial  the  level  channel Scroll  of h i g h e r of  a recognizable  are normally  during  The o u t e r  bank  of  each  i s s u g g e s t e d by t h e  is  steeper  l e v e e . The i r r e g u l a r  and i t s  a n d i n some  profile  of t h e  bank h a s p o s s i b l e a n a l o g u e s i n t h e t e r r a c e a n d s c r o l l b a r  formations above  of the flow  outside  than t h e i n n e r bank, w h i c h i s i r r e g u l a r  cases without inner  the  t o t h e bend  bars  rivers.  of the r i v e r considered overflow  The  are  flat  areas  s u r f a c e bounded by e x p o s e d  to result (Leopold,  f o r m on t h e i n n e r  than average d i s c h a r g e  former  from f l o o d  plain  banks  erosion  Wolman a n d M i l l e r ,  1964 p.  ( c o n v e x ) bank d u r i n g  periods  as a r e s u l t of  m a t e r i a l w h i c h h a s been e r o d e d f r o m o u t e r  mark t h e h i s t o r y o f p o i n t b a r m i g r a t i o n  the  deposition  banks upstream and  (e.g. H i c k i n ,  1974).  F i g . 30. D e f i n i t i o n s k e t c h o f m e a n d e r s . B a s e d i n p a r t on i n L e o p o l d a n d Wolman ( 1 9 6 0 ) .  Fig. 1  103  The of  s i d e - s c a n r e c o r d i n F i g . 22 c o n t a i n s l i t t l e  the presence  four  bends  of e i t h e r  of  this  t e r r a c e s or s c r o l l  reach.  i m p r e s s i o n t h a t the i r r e g u l a r 30) a r e e i t h e r result which 6  channel  resemble  scroll  they  would  m yr~ are  This  is  due  The  of  a  form, which  t o be  means  formed  before  (Chapter 5 ) . I t i s suggested Terrace-like 26b and  s i d e - s c a n r e c o r d showing  a b e n d i n t h e La J o l l a  very  of t h e  close  history  1977  to  at  CSP  profiles  November  time  is  not  r a t e s of  that  these  bottom,  it  31) a n d  is  difficult  R e f l e c t o r B i n F i g . 31  from  fill  too  6 ( F i g . 22), al  (1978)  channel  CSP  9  on  reflectors  "channel  because of side-echo  as  from  these  appears  confirm  to  rises gradually bottom,  and  the it  probable  to i n t e r p r e t  be t h e b u r i e d c h a n n e l  the  records  from the  some right shaded  t h e i n n e r bank a s t h e c h a n n e l m i g r a t e d away  i t s previous position  Truncated  and  r e t u r n s by  expectations.  the  1-2  a t e r r a c e on t h e o u t e r bank  known  Nevertheless,  area  1976  bend a x e s a n d a r e shown i n F i g . 31. B e c a u s e  the  and may  b e f o r e the  happened t o c r o s s the  unambiguously.  left  and  fan-valley.  c o n t a m i n a t i o n of the sub-bottom irregular  or  features are present  of the m o r p h o l o g i c a l development of the  existed  the  i n f i l l e d channels  i n the next reach ( F i g . 26c, F i g . 22). N e l s o n et  Two  to  gives  o n l y f e a t u r e s i n F i g . 22  n e c e s s a r i l y h a v e had  to channel o v e r s p i l l .  present  first  b a r s a r e on t h e p o i n t b a r s o f b e n d s 5  on t h e p o i n t b a r s o f bends 5 ( F i g s . and  record  i n c o n s i s t e n t w i t h the d e p o s i t i o n  i n the area  1  the  f e a t u r e s on t h e s e p o i n t b a r s ( F i g .  overspill.  m e a n d e r s assumed t h i s survey.  this  t h e l e v e e s o f a b a n d o n e d and  from  but  Instead  bars i n  indication  in  (C) n e x t the  left  .to  the  relic  levee which  levee  would  (L).  indicate  1 04  e r o s i o n of p r e v i o u s l y d e p o s i t e d m a t e r i a l a r e could  be  masked  by s i d e - e c h o  not  apparent  from t h e l e v e e w a l l .  but  I n CSP 8 on  t h e o t h e r hand, t h e sub-bottom r e f l e c t o r s b e n e a t h t h e l e v e e s and a b o v e t h e p r e - m i n e s e d i m e n t a p p e a r t o be sediment-water accumulation  interface without  at  the  significant  conformable time,  lateral  with  indicating migration  the local  of  the  channel.  1977 CSP 8  10  Fig. 1977,  ms  31. S e i s m i c profiles l o o k i n g down-channel.  across  t h e meander r e a c h ,  January  105  Perhaps  t h e most i n t e r e s t i n g  f e a t u r e of t h e meanders i s t h e  d e c r e a s e i n w a v e l e n g t h and a s l i g h t distance  down-channel  and  wavelengths (w),  (L)  the l o c a l  Wolman of  s e c t i o n below  (1957,  meanders  1960)  in  Stream and  alluvial  have  the  meanders  shown  that  L =  (4.2)  4.7r '  (4.3)  2  data  i n e a c h p a r a m e t e r . E q u a t i o n s ( 4 . 1 ) and  is  that  in  plan  i n d e p e n d e n t o f s c a l e . The  appears  to  view  the  (4.2)  geometry  v a l u e s of the  i t  26b,  this  r e a c h on t h e b a s i s o f t h e b o t t o m The  is  very  parameters  second  of  s t r e a m b r e a d t h of t h e water  distribution  although  surface  echo-sounding  of suspended  13 and  the  from  d i f f i c u l t to define a channel width for profile  w i d t h o f a r i v e r c a n be d e t e r m i n e d  here,  of  apply with reasonable accuracy to  Fig.  in F i g s .  for  i n flume experiments, i n the G u l f  t h i s meander s y s t e m a s w e l l . As s h o u l d be r e a d i l y a p p a r e n t  done  by  (4.1)  rivers,  observation  relations  bends.  the  L = 10.9w  o u r s y s t e m a r e s u m m a r i z e d i n T a b l e V I I I . The  above  bend.  i n s t r e a m s on g l a c i e r s , and embrace a r a n g e o f 5 t o 7  o r d e r s of magnitude  for  the s i x t h  u n i t s . T h e s e r e l a t i o n s were b a s e d on e m p i r i c a l  meanders  with  r a d i u s o f c u r v a t u r e ( r ) and t h e d i s c h a r g e (Q)  1  codify  amplitude  are r e l a t e d t o the channel w i d t h  L = 20Q / i n MKS  in  ( F i g . 29, T a b l e V I I I ) b e f o r e t e r m i n a t i n g  a b r u p t l y t o form the s t r a i g h t Leopold  increase  14, w o u l d  from  the  cross-  i n plan view. T h i s cannot p r o f i l e s which  material within be u s e f u l  a t the axes of t h e  indicate  the channel, l i k e  in this  r e g a r d i n any  be the  that  future  106  studies channel the  of  systems  of  this  kind.  width at the cross-overs  angle  ( F i g . 2 6 d ) , and  which  d i f f e r e n c e may  i n Table  i s lower  than  to the  V I I I . The mean v a l u e that expected  using the  correcting  b e t w e e n t h e l i n e and t h e p e r p e n d i c u l a r  a x i s gives the widths 7.1±0.9,  Alternatively,  from  for  channel  of  L/w  is  ( 4 . 2 ) , but the  be due t o o v e r e s t i m a t i n g w ( s e e F i g . 2 6 d ) .  I t h a s a l s o been s u g g e s t e d  that at a given discharge,  there  i s a t h r e s h o l d s l o p e such t h a t r i v e r s w i t h s l o p e s l e s s than threshold are straight (Ackers  and  Charlton,  second, higher and  whereas those  Wolman,  1970;  with steeper  Schum  and  threshold slope, channels 1960;  Ackers  and C h a r l t o n ,  slopes  Khan, are  the  meander  1 9 7 2 ) . Above a  braided  (Leopold  1970; Schum and Kahn,  1972). T a b l e V I I I . Meander d i m e n s i o n s i n m. The meander The mean v a l u e o f L / r i s 3.8±0.4. Bend 1 2 3 4 5 6  4.3.3  Lower  L (m)  r (m)  L/r  a (m)  w (m)  L/w  518 475 579 536 317 378  180 1 10 207 1 55 82 76  2.9 4.3 2.8 3.5 3.9 5.0  91 1 02 1 22 1 10 101 11 6  64 64  8.1 7.4  54 54  5.9 7.0  (Fig. widen, (Fig.  bottom  slope  20), a s t i l l and  i s a.  Reach  The u p p e r p a r t o f t h i s gradual  amplitude  reach  is  characterized  by  a  more  (0.47°, F i g . 2 5 ) , t h e a b s e n c e o f meanders  lower  channel  symmetric  26c), a terrace-like  hand s i d e o f t h e c h a n n e l .  levees  relief  with  (Fig. 26c).  s t r u c t u r e i s present  no  tendency  In  lines  15-17  the  right-  on  S i m i l a r s t r u c t u r e s are apparent  to  i n the  107  s i d e - s c a n r e c o r d t a k e n seven months l a t e r  (Fig.  They  channel  suggest  a  lateral  shift  of  the  22,  F i g . 29).  axis  without  m e a n d e r i n g i n t h i s p o r t i o n of the r e a c h . The  data i n Table VII i n d i c a t e that t h i s  reach  v a r i a b l e , b o t h a s t o t h e number o f c h a n n e l s and It  is  to  be . e x p e c t e d t h a t  relic  seismic p r o f i l e s across t h i s part material  had  banks and  bottom.  profiles,  in  i n September V I I ) . The the  Fig.  32.  different No  acoustic  such f e a t u r e s  the  were  s p i t e of the d i s a p p e a r a n c e 1976  w h i c h had  from  the  is clearly This  if  obvious  the  in  fill  channel  the  1977  o f a c h a n n e l a t ICM-14 earlier  h a v e been  interface.  i n d i c a t e d , however, i n the  c h a n n e l may  positions.  be p r e s e n t i n  inlet  been q u i t e p r o n o u n c e d  sediment-water  highly  impedance than the  e c h o f r o m t h e b u r i e d c h a n n e l may  echo  channel  a  their  c h a n n e l s would of  is  (Table  masked  Infilling  1975  have been t h a t o b s e r v e d  interpretation  rate  m yr"  1  Chapter The  which,  although  high,  lower s e c t i o n of t h i s  about  5  i s not out of t h e q u e s t i o n (see  Point  reach e x h i b i t s a further  f o r t h e c h a n n e l t o w i d e n and  hugs t h e n o r t h w a l l p r i o r  observed  of  This  5).  i n s l o p e and a tendency  Hankin  deposition  in  on t h e n o r t h  (Table V i l a ) .  local  of a  profiles  s i d e o f t h e i n l e t a t CSP-14 t h e p r e v i o u s y e a r requires a  by  to  its  disappearance  s h o a l as i t  east  area. T h i s i s c o n s i s t e n t w i t h the channel  i n the January  1977  CSP  survey.  decrease  of  the  pattern  CSP  12  F i g . 32. S e i s m i c p r o f i l e s a c r o s s t h e a r e a of t h e r e a c h i n 1975, l o o k i n g d o w n - i n l e t .  197  109  4.4  The  A p r o n Regime  The CSS  next  survey  V e c t o r , at which  channel (Fig.  had  was  conducted  time the  i n September  upper  reach  of  c o m p l e t e l y d i s a p p e a r e d u n d e r an  3 3 ) . The  meander r e a c h ,  'apron'  partially  of  tailing  infilled,  survey  i n l a t e Febuary  slump  s c a r s o r i n c i p i e n t c h a n n e l s m a r k e d b o t h t h e e a s t and  speed  correction  between  depth  grid  position  of  sounding  speed  i n t e r v a l was  60 m.  both  this  e r r o r due contouring  grid.  difference  at  be  a  most  on  by  linear  probable error  an in  Systematic  The  data  calculated by 0.3  m s~  1  in  the  v a l u e of or l e s s  i n the  line  depth,  the from  which  i n t e r s e c t i o n s agreed on  or a s l i g h t  sloping  the  tidal  o f t h e map  large  errors  bottoms.  in  to  composite  correction.  offset  is  different  r e a s o n a b l e e s t i m a t e of t h e  g r i d c o u l d produce steeply  s  o r an o f f s e t  l i n e s were o f t e n r u n  b o t h t o p o s i t i o n i n g and  the d i f f e r e n c e  sounding  5  s i n c e such  should  the  1976  s u r v e y s . U s i n g a c o n s t a n t v a l u e of c '  depths  days,  depth  to specify.  the p r e d i c t e d , t i d e s ,  amounts t o a s y s t e m a t i c e r r o r of 0.02%  ±0.2m, and  The  is difficult  overlay  in  within  the  l i n e s a t the i n t e r s e c t i o n s of  t o 50 m d e p t h d i f f e r e d  The  from  s  the  100 m  negligible.  west  f r o m t h e use o f a c o n s t a n t c '/c , d i f f e r e n c e s  b e t w e e n t h e a c t u a l and  to  later  surveys  a p p l y i n g the a p p r o p r i a t e  contour  difference  errors could arise  that  maps,  constructed  i n e a c h c a s e , by r e a d i n g t h e  o v e r l a y g r i d . The given  a l s o dominant i n a  ( F i g . 3 4 ) . I n b o t h of t h e s e  ( F i g . 35) was  bathymetric  interpolation  a  was  apron.  A d i f f e r e n c e map 1978  1979  was  the  meandering  discernible.  and  regime  the  from  still  f l a n k s of the  This  though  1978  Hand-  relative the  to  depth  T h i s type of e r r o r i s  110  b e l i e v e d t o be r e s p o n s i b l e f o r t h e l a r g e n e g a t i v e d i f f e r e n c e s a t the west end o f t h e g r i d  i n F i g . 3 5 , on t h e n o r t h  Large p o s i t i v e d i f f e r e n c e s  in  the  rest  side.  of  the  map  are  l a r g e l y c o n f i n e d t o t h e c h a n n e l a x i s . The e s t i m a t e d a c c u m u l a t i o n is  small  upper of  and  sometimes  reach and near  significant  n e g a t i v e on t h e l e v e e s b o t h a l o n g t h e  t h e bend axes  i n the middle  negative differences  i s p r e s e n t near  o v e r t h e f o r m e r w e s t l e v e e a n d e x t e n d s down t h e the t a i l i n g mentioned  apron  previously.  over  a  Accumulation  i s pronounced  r e a c h , and  appears  barrier  exact date of only  pronounced at  ICM  personal  the  disappearance  of  i t was s o m e t i m e a f t e r  was f i r s t  communication), of  previous  two  necessarily reach.  that  ( F i g . 19)  stability  of  east of the  to  have  the  channel  years.  The  simultaneous  been (1974)  deposit  acted  f r o m t h e w a s t e dump. the  observed  which  was  profile change with  in  the  channel  in April  unusual at  channel  because  profile  obliteration  profile  1978  that location  this  is  22 December, 1977. A  and p e r s i s t e n t change i n t h e monthly 8  flank  t o t h e d o w n - i n l e t t r a n s p o r t o f mine  waste - i n c l u d i n g both t a i l i n g and m a t e r i a l  unknown;  west  t h a t t h e main l o b e o f t h e t a i l i n g  topographic  The  zone  the o u t f a l l  t h e e a s t than over t h e west l e v e e . Johnson  a l s o suggested as  A  i n t h e z o n e m a r k e d by t h e p o s s i b l e s l u m p s c a r s  former p o s i t i o n o f t h e upper greater  reach.  (Hillis, of  the  over the was  not  o f t h e upper  400  0  400  . D e p t h d i f f e r e n c e map, November 1976 - S e p t e m b e r ion. Negative d i f f e r e n c e s are shaded.  800  1978. P o s i t i v e  values  113  A general c o l l a p s e of the levees along upper reach pinched  i s not suggested  the  length  by F i g . 3 5 . I f t h e c h a n n e l  of  the  h a d been  o f f by a s l u m p o f t h e w e s t l e v e e n e a r t h e o u t f a l l , t h e  r e s u l t w o u l d s u r e l y h a v e been t h e d i v e r s i o n o f t h e f l o w down t h e west f l a n k w i t h o u t  filling  blockage  a t t h e lower  readily  eroded,  end of t h i s  throughout the  of  the  in  was  discharge.  Since  i t is  discharged  would  have  not  have  been  decrease  in  the  axial  slope,  i t s disappearance,  5.9x10  the  m,  the  equivalent  unlikely  that  a l l of  s  3  settled  volume  of  o f 24 d a y s the  i n t h e upper r e a c h ,  tailing  i t may h a v e  s e v e r a l months t o f i l l . Such a b l o c k a g e  may h a v e been c a u s e d by a l e v e e  slump,  or  a s l u m p f r o m t h e w a s t e dump. A m a j o r s l u m p f r o m t h e w e s t e n d  o f t h e dump d i d o c c u r effect  upon  the  of  the  conjunction down-inlet cause  a  dump. with  i n mid June,  upper  o c c u r r e d on 30 J a n . , end  would  and t h e r e f o r e i n c r e a s e d d e p o s i t i o n  the reach. Before reach  by  a  flow  upper  taken  reach  a n d r a p i d d e p o s i t i o n w o u l d have o c c u r r e d on i t s  upstream f a c e , r e s u l t i n g decceleration  t h e u p p e r r e a c h . On t h e o t h e r h a n d , a  reach  (Figs.  but  The the  first 1977  or  two  previously  collapse  of  the  slumps  have c a u s e d deposited  this hypothesis,  obvious slumps  may,  in  sufficient  material  to  l e v e e a t t h e p o i n t most  s e n s i t i v e t o s u c h movement - t h e b a s e o f t h e u p p e r Pursuing  no  1978, b u t a t t h e e a s t  of' these  precursor,  had  23 a n d 2 4 ) . M a j o r  11 M a r . , a n d 11 S e p t .  mass-movement o f breach  1977,  i t i s suggested  reach.  that  after  a p r o n was f o r m e d by f i l l i n g  t h e upper r e a c h ,  was  down t h e west b u t a l s o down t h e e a s t  diverted  flank,  principally  resulting  i n erosion  of  previously  the discharge  the  deposited  plume  tailing,  11 4  particularly apron  i n the area c l o s e t o the o u t f a l l .  coincided approximately  which  it  r e p l a c e d , and  and  waste overburden  4.5  Rechannelized By A u g u s t  flank  of  available  the  The  c r e s t of  w i t h the a x i s of the  upper  a c t e d as a b a r r i e r b e h i n d  continued to  which  the  reach tailing  collect.  Regime  1979,  a second  tailing  channel  apron  had  developed  ( F i g . 36),  west  steepest  was  marked by p r e s u m e d s l u m p s c a r s ( F i g . 3 3 ) . Even by F e b r u a r y ,  1979  were  indications  of  a l s o the area t h a t i n  slope  1978  there  t o t h e f l o w . T h i s was  the  on t h e  a  channel  ( F i g . 3 4 ) . The  August survey d i f f e r e d  was  from  conducted  equipment  discussed  were o b t a i n e d f r o m was  the  5  in  shore  cross-angles  intervals  (1-2 min.)  among t h e s h o r e A detailed  UBC  Chapter  from  lines  were  with  the  s t a t i o n s and  in that position  t o w a r d s o r away f r o m one  station  from the  second  launch.  l a u n c h was  survey of the Hankin  the  extremely  steep-sided  channel  was  outfall  ( F i g . 37, p r o f i l e s  The  not p h y s i c a l l y c o n t i n u o u s  1979  channel  morphologically distinct upper  channel  conducted  P o i n t a r e a was  reach extends  from  r i g h t , w i t h levees which  debouched  at  time  Communication by  radio.  made a t  this  a very  deep  ( F i g . 36).  This  time, d e l i n e a t i n g a pronounced scour hole i n t o which and  fixes launch  from  the  sounding  The  determined  signalled  area  the o t h e r s i n t h a t i t  launch 3, and  in this  stations with theodolites.  guided along s t r a i g h t  while  m  developing  w i t h the channel  off  the  10-15). system  is  and p h y s i c a l l y the o u t f a l l  divisible separated  into reaches.  down-inlet, c u r v i n g to  a r e more o r l e s s p r o n o u n c e d  (Figs.  two The the 37a  115  and  b ) , and then d i s a p p e a r s b e f o r e t h e s t a r t  As  in  t h e 1976-77 s y s t e m ,  u n d e r g o an i n i t i a l and  and  at l i n e the  i n c r e a s e near  then decrease  in t h i s  that the h o r i z o n t a l (Figs.  is  reach other  channel  disappears Some  which  is  a x i s a n d F i g . 13.  i n c r e a s e s downstream channels  consistent  of  a b a n d o n e d by  r e s o l u t i o n was  higher  beam t r a n s d u c e r ,  s c a l e i s much c o a r s e r t h a n  the previous left  with the rightward  The  relief  ( F i g . 37c), a t r a i t  only c l o s e to the o u t f a l l .  of  the  observed i n  The w a l l s o f t h e  r e a c h a r e p r e c i p i t o u s a n d no l e v e e s a r e p r e s e n t ,  i n d i c a t i n g that t h i s channel  Fig.  and 2 ) ,  24 a n d 2 6 ) . P r e f e r e n t i a l d e p o s i t i o n on t h e  indicated,  in this  1  irregular.  slump s c a r s o r c h a n n e l s  f l o w . Note t h a t h o r i z o n t a l  c u r v a t u r e of the channel  the  (lines  survey because of t h e use of a narrower  profiles  lower  the o u t f a l l  reach.  and c r o s s - s e c t i o n  downstream b e f o r e t h e channel  f e a t u r e s may be e i t h e r  levee  relief  13. T h e s e b o t t o m p r o f i l e s a r e h i g h l y  the c o n t i n u o u s  and  the channel  of t h e lower  36. B a t h y m e t r y ,  i s an e r o s i o n a l f e a t u r e .  A u g u s t 1979.  37. C r o s s - c h a n n e l Lower c h a n n e l . See  profiles, F i g . 37  August  1979,  for locations.  looking  down-channel,  ( a ) and  (b) Upper  channeI;  1 17  F i g . 38. S o u n d i n g l i n e s c o r r e s p o n d i n g C h a n n e l s are i n d i c a t e d by s o l i d l i n e s . The  axial  profile  of the channel  s l o p e o f t h e upper r e a c h d e c r e a s e s lower  reach  to profiles  increases.  The  i s plotted  1.93°  in  the f i r s t  .1.24° i n t h e n e x t  slope  of  is  reach which  tempting  reaches  is  upper  t h a t the lower  c u r r e n t s , and  that  by d e p o s i t i o n f r o m  i s discussed further  reach area  is  5.77°  c o n s t a n t v a l u e of of the channel  (0.58°) a b o v e  3 km f r o m  the  reach  d e c r e a s i n g from  i n slope  begins approximately  filled  Thi.s s u g g e s t i o n  i n F i g . 3 9 . The  1 km s e c t i o n . The d i s a p p e a r a n c e  t o suggest  type t u r b i d i t y  the  km, w i t h a r e l a t i v e l y  i s a c c o m p a n i e d by a f u r t h e r d e c r e a s e lower  F i g . 31.  downstream, w h i l e t h a t of t h e  c o m p a r a b l e t o t h a t o f t h e 1976-77 s y s t e m , to  in  the  the o u t f a l l . I t  i s eroded between  the continuous  i n the f o l l o w i n g  by s u r g e the  two  discharge. chapters.  118  AXIAL DISTANCE  Fig.  39. Depth o f c h a n n e l A bathymetric  from  the  1977  (km)  a x i s , A u g u s t 1979.  map o f t h e H a n k i n P o i n t a r e a  CSP  survey  and i s p r e s e n t e d  d e p t h d i f f e r e n c e map i n F i g . 40b. T h i s dramatic  change  in  sedimentation  during (see  Point  Chapter  1). Flood  occurs  primarily  a  area  tide  period  of  to  i n the increases  early  t i d e c u r r e n t s as h i g h as 2 m s " ( S t u c c h i and during  of t h e deep water i n t h e R u p e r t - H o l b e r g represents  an  of t h e deep water  O c t o b e r t h r o u g h December. I t i s d u r i n g  presumably  flood  from l a t e w i n t e r  10 m f r o m t h e b o t t o m  rainfall  i n F i g . 40a, and a  r e g i m e . I t i s t o be e x p e c t e d  as the s a l i n i t y  t h e p e r i o d o f low r u n o f f  been m e a s u r e d Heavy  area  constructed  i s clearly  t h a t e r o s i v e bottom c u r r e n t s d e v e l o p d u r i n g Hankin  was  Farmer,  fall 1  have  1976).  t h e autumn months o f  t h i s period that basin  takes  dilution  place,  of r e l a t i v e quiescence  and  i n the  119  near-bottom zone. Noting in  early  January,  seems l i k e l y due  to this  currents.  that  t h e 1977 CSP s u r v e y was  whereas  the  that the differences seasonal  change  in  I t i s also possible  hole  was a b e t t e d  area  i m p l i e d by t h e t r a n s i t i o n  conducted  1979 s u r v e y was i n A u g u s t , i t i n bathymetry  the  that  i n t h i s area are  amplitude  of  the  bottom  t h e development of t h e scour  by t h e r e d u c e d t r a n s p o r t  of  tailing  f r o m one c h a n n e l i z e d  into  the  state to the  next. This  transition,  e m b o d i e d i n F i g s . 2 0 , 3 3 , 34 a n d 36, h a s  some i n t e r e s t i n g i m p l i c a t i o n s r e g a r d i n g leveed a  direction  in  which  the  downslope  f o r c e a c t i n g on t h e f l o w  determined  feature of  by  a  flow,  combination of the steepest  permitting  would appear t h a t Having  i tt o maintain  an  incipient  b u i l d i n g by p r e f e r e n t i a l d e p o s i t i o n overspill  flows  further  inhibit  initial  route.  and  or  lateral Deposition  the  process.  balances  slope.  approach  capacity.  juvenile channel, the  loss  and  levee-  channel  from  the axis  reinforce  on t h e c h a n n e l w a l l s  record  to  a n d any  the  a l s o o c c u r s w i t h i n t h e c h a n n e l , and  walls' i n the side-scan  expected  will  divergence  latter  t o t h e c h a n n e l b o t t o m . The i r r e g u l a r f e a t u r e s  I f deposition  the  i t s excess density. I t  close to  divergence  of  slope  c h a n n e l - d e e p e n i n g by s c o u r a l o n g  some o f t h e m a t e r i a l d e p o s i t e d  bottom  the  This  the l a t e r a l  slump s c a r s can a c t i n  established  component  i s a maximum.  i n the bathymetry which i n h i b i t s  the  down  of  c h a n n e l s i n t h i s and s i m i l a r systems. Channels develop i n  gravitational be  the development  will  slide  of t h e levee  ( F i g . 22) a r e i n d i c a t i v e o f s u c h a erosion,  equilibrium  for a  the  channel  given  can  be  discharge-and  120 a.  b.  F i g . 40. ( a ) B a t h y m e t r y " o f f H a n k i n P o i n t i n January 1977 and (b) A u g u s t 1979; (c) Depth d i f f e r e n c e map, H a n k i n P o i n t a r e a ; J a n u a r y 1977 - A u g u s t 1979 (Note change in s c a l e ) . Negative v a l u e s a r e s h a d e d and i n d i c a t e e r o s i o n .  121  4.6  Comparison  w i t h Deep-Sea F a n - V a l l e y s  Fan-valleys which Daly shelf  issue  (1936)  by  from  s u g g e s t e d were  turbidity  to  of  eroded  into  both  sea-level  the  continental  continuous stands  and  entire  intermittent  canyon,  fan  and  slump-generated  were  both  more f r e q u e n t a n d ,  deposited,  more  Holocene.  The  powerful  currents are  idealized  continental  The  Pleistocene  fan-valley Nelson  and  s l o p e a t t h e mouth o f w h i c h  fan)  and  terminates  in  the  u n c h a n n e l i z e d l o w e r f a n . The  strictly  comparable  imposed  by  tidal is  t o t h i s because  the i n l e t  w a l l s and  in that a s t r i c t  the  upper  been  (1973),  canyon  terrigenous  a  system  i n the  Rupert  of the  Inlet  sediments.  part  of  of  i n turn  the  unleveed disappear  system  lateral  the c o m p l i c a t i o n s  present. N e v e r t h e l e s s , a comparison and  Kulm  i s not  confinement introduced  s c o u r i n g of the lower reach i n the Hankin P o i n t  also different  the  i s a depositional leveed  d i s t r i b u t a r y c h a n n e l s on t h e m i d d l e f a n w h i c h on  than  (1978b).  system c o n s i s t s of a submarine  on t h e s u r f a c e o f a f a n o f l a r g e l y  (upper  basis  f o r m a t i o n has  p r e s e n c e of the v a l l e y c h a r a c t e r i z e s the upper  fan  the  from the c o a r s e r m a t e r i a l  the  (1966),  system,  record, these events  ( 1 9 7 4 ) , N e l s o n e t a l (1978) a n d Normark  The  valley  during  s u b j e c t o f f a n and  r e v i e w e d by S h e p a r d and D i l l Normark  judging  with  extended  fan-val.ley  turbidity  the t u r b i d i t e s present i n the g e o l o g i c a l  storm-  associated  u s u a l l y c o n s i d e r e d t o be t h e p r i m a r y a c t i v e a g e n t . On of  canyons,  g l a c i a t i o n . T h i s c o n c e p t u a l model has been  encompass t h e  although  mouths o f s u b m a r i n e  currents,  generated, d u r i n g the lower periods  the  area.  by It  a n a l o g y t o the canyon  i s not  i s made b e t w e e n  canyon  r e a c h , ' a n d b e t w e e n t h e f a n - v a l l e y and  the  the middle  122  and l o w e r r e a c h e s . Normark  (1978b)  further  v a l l e y and m e a n d e r i n g examples  the  distinguishes  or b r a i d e d v a l l e y - f l o o r  deep-tow r e s u l t s  channel).  Ascension  The  latter  downcutting, which i s u n c h a r a c t e r i s t i c (Hess  and  scale  events  than  (incised,  represents  erosional  of a d e p o s i t i o n a l  regime  f e a t u r e s may  fan-valley  glaciers.  c h a n n e l s and The  dense  fan-valleys w i l l  much  a t t e n t i o n . One  of t h e d i f f i c u l t i e s  i s t h a t t h e s u r v e y l i n e s a r e sometimes to  resolve  a  upper in  with  a  reach  fan-valley  h a s n o t been i n c l u d e d b e c a u s e  have  been  result  of  channel  cross-over  1970).  M i d - O c e a n C h a n n e l d o e s meander  (Chough  The  list  of s t r a i g h t  or  exhibits  of  similar  low-amplitude  those  meanders.  appears to  Northwest  and H e s s e ,  m e a n d e r s a r e o f low a m p l i t u d e ( a / L < 0 . 0 5 ) . The e t a l , 1970)  list  s l o p e of  The  canyon  ( S h e p a r d , 1968;  i t s meander  (Normark,  (Nelson  sufficiently  system i s analogous t o a  1969)  fan-valley  deep-sea  on t h e a x i a l  c o n t a i n i n g pronounced  t h i s c o n t e x t . The M o n t e r e y  Ascension  with  not  meander. N e v e r t h e l e s s , m e a n d e r s h a v e been  reach of the Rupert I n l e t  the  thesis.  not  c h a n n e l , as i n Rupert I n l e t . T a b l e IXa i s a  fan-valleys  of  valley-floor  i n s u b m a r i n e c h a n n e l s has  f o u n d and t h e i r p r e s e n c e a p p e a r s t o depend the  between  n o t be drawn i n t h i s  phenomenon o f m e a n d e r i n g  received systems  I n any c a s e , t h e d i s t i n c t i o n  be  itself,  p e r h a p s a s t h e r a t e o f s e d i m e n t s u p p l y waned w i t h t h e r e t r e a t the  as  (braided  fan-valley  the  fan-  channels, using  N o r m a r k , 1976; N o r m a r k , 1 9 7 8 b ) . Such  c a u s e d by s m a l l e r  the  f o r t h e Navy f a n - v a l l e y  v a l l e y - f l o o r c h a n n e l s ) and t h e meandering  between  Komar, to  to  the nearby Atlantic  1976), but the  Astoria  fan-valley  l o w - a m p l i t u d e meanders. A  meandering  fan-valleys  is  1 23  given  i n Table  IXb.  Table IXa. A x i a l a meander r e a c h .  slopes ( i n degrees) Canyon  Amazon C o n e Bengal f a n Coronado La J o l l a " * ** Navy Redondo Rupert I n l e t  M i d d l e (meander) Lower reach 0.74 0.29 1 .2 1.9-0.87 0.48 0.23 1 .05 0.91  1  2  5.7 2.3 2.1 0.57 2.1 2.2  3  5  5  * **  above below  of submarine c h a n n e l s  with  reach 0.42 0.09 0.65 0.48 0.06 1 .95 0.47  tributary tributary  Table IXb. A x i a l s l o p e s of submarine channels meander r e a c h o r low a m p l i t u d e m e a n d e r s . Astoria Cascadia Congo NW A t l a n t i c  0.95  7  DOC  either  no  0.30 <0.09 0.23 0.04  8  0.57  3  with  9  D a m u t h and Kumar < 1 9 7 5 ) , C u r r a y and Moore ( 1 9 7 1 ) , S h e p a r d and D i l l ( 1 9 6 6 ) , " S h e p a r d and B u f f i n g t o n ( 1 9 6 8 ) , N o r m a r k and P i p e r ( 1 9 7 2 ) , H a n e r ( 1 9 7 1 ) , ' N e l s o n e t a l ( 1 9 7 0 ) , " G r i g g s and Kulm ( 1 9 7 0 ) , C h o u g h and H e s s e ( 1 9 7 6 ) . 1  2  3  5  6  9  On  the-  reach appears  basis  o f t h e s e d a t a , t h e d e v e l o p m e n t of a meander  to require a s u f f i c i e n t l y  such cases  the s e c t i o n  laterally  constricted.  Coronado  fan-valleys  (leftward) Rupert  near  immediately Although exhibit  steep  upstream the  a  Redondo,  Astoria  w i d t h and  right-angle  and bend the  and Navy f a n - v a l l e y s  i t s m e a n d e r s a r e o f low  relief  often  Jolla  f a n - v a l l e y a l s o bends s h a r p l y t o the l e f t  t h e c a n y o n mouth, b u t The  La  In  t h e r i g h t w a r d bend o f  I n l e t c h a n n e l , t h e Amazon, B e n g a l  n o t . The  slope.  i s s t e e p e r and  nearly  t h e c a n y o n mouth l i k e  axial  of most o f t h e s e  do  near  amplitude.  fan-valleys  decrease  124  downstream. In the case  o f t h e Amazon Cone and  v a l l e y , p a r t of t h i s d e c r e a s e channels. behaviour (1971)  although  reaches,  a  not  relief  increases.  clear.  of  This  Of has  Buffington,  is  s l o p e i n c r e a s e s between  the  feature  which  grid  is  the  has in  is relatively  Cone  and then  (Fig. Inlet  41)  sparse  thalweg, not be  of t h e C a s c a d i a  lower  survey  reach  downstream therefore Table  as  the real.  fan-valley  Bengal  been  channel  the  (Shepard  split  the meanders decay  slope  into  and  decreases,  channel. as  I X a . In the s e c t i o n above the t r i b u t a r y  and  lower  two  but  sections,  reach,  the  thalweg  channel.  of t h e m e a n d e r s i n t h e N a v y , Redondo, Amazon fan-valleys  s t o p a b r u p t l y . The exhibits  coverage  fan-valley  of t h e mouth o f a t r i b u t a r y  upstream of the s t r a i g h t  amplitudes  IX, t h e La J o l l a  I t i s s t e e p l y s l o p i n g and  meanders w i t h i n a . s t r a i g h t The  i n Table  densest  1968).  again  immediately  discussed  t o the c o n t r i b u t i o n s of i t s s e v e r a l t r i b u t a r i e s ,  t o form a s t r a i g h t  indicated  Redondo  i s Vancouver S e a - V a l l e y .  received  channel  Haner  the  i n t h e meander r e a c h may  the systems l i s t e d  develop  the  fan-valley  downstream i n c r e a s e i n the r e l i e f  among w h i c h  and  the  because the sounding  increase i n width  fan-  distributary  the l i n e s are not p e r p e n d i c u l a r t o the c h a n n e l  i s p r o b a b l y due  The  to loss to  respect i s  i n t h a t the a x i a l  the lower  Bengal  t h e C a s c a d i a a r e e x c e p t i o n s , and  downstream, the w i d t h  However,  apparent The  that  exceptional  later.  be due  of the Coronado i n t h i s  meander and  and  Redondo and  indicates  decreases also  The  may  the  some  (Figs.  i n c r e a s e w i t h d i s t a n c e downstream  Redondo c a n y o n and  interesting 20  and  25).  parallels The  fan-valley to  slopes  the of t h e  system Rupert upper  125  ( c a n y o n ) and meander r e a c h e s a r e v i r t u a l l y lower  an  same,  but  r e a c h o f t h e Redondo i s s t e e p e r and a p p e a r s t o be  (Haner, state  the  1 9 7 1 ) . The  transition  i s accompanied  increase  Rupert I n l e t  in  by an  from the meandering  increase  width);  braided  to the  i n s l o p e from  the  braided  1° t o 2°  (and  the m e a n d e r i n g - s t r a i g h t t r a n s i t i o n i n  by a d e c r e a s e f r o m  1° t o  0.5°.  3 J  5  F i g . 4 1 . Redondo c a n y o n 1971 ) . Fig. systems  42 in  is  a  and  sketch  fan-valley of  the  trajectories  s l o p e - d i s c h a r g e parameter  straight-meandering  section. morphology  in  Haner,  of t h e s e which  ( 1 9 7 2 ) , A c k e r s and  (1970) and L e o p o l d and Wolman ( 1 9 6 0 ) . is  space,  from  km  two the  and m e a n d e r i n g - b r a i d e d t h r e s h o l d s h a v e been  drawn a s s u g g e s t e d by Schum and Khan  discharge  (adapted  nm  i  1  assumed  Note  that  may  explain  At  t o be p r o p o r t i o n a l the  a  given  slope,  t o the channel  discharge-dependence  some v a r i a t i o n s  Charlton  of  i n Table IX.  the  the  crossplan  126  1.0  UJ  e  0.1 br  0.01  2.8 x 10*  2.8  2.8 x 1 0  2.8 x 10  2  2.8 x  3  10  4  BANKFULL DISCHARGE (m s ) 3  _1  Fig. 42. H y p o t h e t i c a l s u b m a r i n e c h a n n e l t r a j e c t o r i e s i n s l o p e d i s c h a r g e s p a c e . The b r o k e n l i n e i s t h a t s e p a r a t i n g b r a i d e d f r o m meandering and s t r a i g h t r i v e r s (Leopold a n d Wolman, 1960). Meander c u r v a t u r e i n c r e a s e s w i t h d e c r e a s i n g s l o p e . The meander  Redondo reach  f a n - v a l l e y i s 10 m d e e p and 300 m w i d e i n t h e  (Haner, 1971), i n d i c a t i n g  of m a g n i t u d e g r e a t e r upper r e a c h occurs reach.  than t h a t  i s confined  until  the  a c r o s s - s e c t i o n an channel.  The  by t h e c a n y o n w a l l s ' s o no o v e r s p i l l  loss  flow  i n the Rupert I n l e t  order  enters  L o s s e s by o v e r s p i l l  t h e more g e n t l y s l o p i n g meander along  the e n t i r e  l e n g t h of the Rupert I n l e t channel.  Because t h e s l o p e  increases  upon  in  leaving  potential  the  increase  The s u g g e s t i o n submarine the  channels  a r e assumed t o o c c u r  meander  reach  the  Redondo, t h e r e  in discharge. i s , then, is  that  the  plan  morphology  of  c o n t r o l l e d by b o t h t h e b o t t o m s l o p e  and  r a t e of l o s s of m a t e r i a l through both channel  overspill  a x i a l d e p o s i t i o n . The o b s e r v e d d e c r e a s e  i n w a v e l e n g t h and  of  meanders  curvature  of  is a  the  downstream i s c o n s i s t e n t  Rupert with  Inlet a  gradually  with  waning  and  radius  distance flow  (see  127  Equations  4.1  to  4.3).  These  d i f f e r e n c e between s u b a e r i a l currents:  in  overlying  fluid  the  latter  a r e e f f e c t s of t h e  rivers case,  and t h e r e s u l t i n g  of  even f o r r i v e r s .  is  the Rupert  readily,  difference.  discharge  is  not  well  Because t h e meandering p r o c e s s i t s e l f i s thresholds  are  available.  i t obvious t h a t channels s u b j e c t e d t o the a c t i o n of  t u r b i d i t y c u r r e n t s u r g e s s h o u l d be c o m p a r a b l e The r e l a t i v e  the flow with the  i n F i g . 42 a r e s p e c u l a t i v e . The d e p e n d e n c e  n o t w e l l u n d e r s t o o d , no t h e o r e t i c a l Neither  of  turbidity  o v e r s p i l l o c c u r s more  e i t h e r t h r e s h o l d upon t h e s l o p e a n d  known  channelized  mixing  both because of t h e s m a l l e r d e n s i t y The t r a j e c t o r i e s  and  fundamental  importance  Inlet  system  o f c o n t i n u o u s and  to river  surge-type  i s d i s c u s s e d i n Chapter  8.  channels. flows  in  1 28  CHAPTER 5 SEDIMENTS The s u r f i c i a l spatial  s e d i m e n t s were s a m p l e d p r i n c i p a l l y  variations  in  to  relate  grain-size  and copper c o n c e n t r a t i o n t o  changes i n t h e s e d i m e n t a t i o n regime  i m p l i e d by t h e m o r p h o l o g y o f  the  establish  d e p o s i t . . C o r e s were  taken  to  the  t u r b i d i t e s and t h e r e b y d e t e r m i n e t u r b i d i t y - s u r g e The 700 ppm  Cu  content  of  the t a i l i n g  (Evans and P o l i n g ,  presence  of  frequencies.  b e f o r e d i s c h a r g e i s about  1975), a l t h o u g h i t can vary w i t h o r e -  t y p e a n d e x t r a c t i o n e f f i c i e n c y . An a n a l y s i s o f d a t a c o l l e c t e d by the  mine  the  (Hay, 1978b) i n d i c a t e d t h a t t h e c o n c e n t r a t i o n o f Cu  tailing  outfall, found. to  near which l e v e l s It  increasing distance  2-3 t i m e s g r e a t e r  was d e c i d e d t o e x p l o i t  than  from t h e  700 ppm  were  t h i s d e p e n d e n c e i n an a t t e m p t  identify copper-bearing t u r b i d i t e s with a near-outfall  of  origin.  because of  deposit decreased with  Some  iron  d e t e r m i n a t i o n s were  of t h e i r p o t e n t i a l  t h e sediment  specific  in  a l s o made,  b e a r i n g on t h e g r a i n - s i z e  point partly  dependence  gravity.  5.1 S a m p l i n g a n d L a b o r a t o r y T e c h n i q u e s The  surficial  s e d i m e n t s were s a m p l e d w i t h a S h i p e k g r a b i n  December 1977, F e b r u a r y 1979 a n d A u g u s t subsamples  were  taken  s m a l l p i s t o n c o r e r made subsample the  was  from  a  50 cm  taken during  100-150  3  f o r metal analysis  the f i r s t  plastic  syringe.  temperature f o r s i z e  The s e d i m e n t c o l u m n was s a m p l e d were  Two  cm  3  f r o m e a c h g r a b by t h e r e p e a t e d u s e o f a  s t o r e d a t ambient  o t h e r was f r o z e n  1979.  by  channelized  One  analysis;  (Cu a n d F e ) . gravity regime  corer.  Cores  i n November 1976  129  and  December  study  by  February phase.  1977. The  Davis  1977 c o r e s were u s e d  (1978).  for  the  stability  C o r e s o f t h e a p r o n r e g i m e were t a k e n i n  1979. No c o r e s  were  taken  during  The s a m p l e p o s i t i o n s were d e t e r m i n e d  the  rechannelized  with the Trisponder  s y s t e m a t t h e t i m e o f p e n e t r a t i o n , e x c e p t i n g t h e 1977 c o r e s cores  i n Holberg The  f o r w h i c h r a d a r was  under-consolidated  sediment  column  difficulties corer  Inlet  in  in  state  deposits  of  of  used.  the  tailing  upper mud  a  barrel-less  corer  in  caused  1977  Boomerang c o r e r , m o d i f i e d  f o r use w i t h a w i n c h  1979.  core  top  of  the  liner  below t h e base of the w e i g h t - s t a n d , sediments  the  cores  (Appendix  in  soft  u p p e r 30-50 cm o f t h e s e d i m e n t c o l u m n were  lost.  were  orientation  usually  during  which  meant  that  obtained with l i t t l e  withdrawal  only  in a  from the c o r e r w i t h o u t  both  poorly  upper p a r t of t h e c o r e and a l l o w e d  consolidated  minimized  of t h e c o r e - c a t c h e r w i t h m i n i m a l the  of  an u n s u p p o r t e d  liners  for  core  three  liner.  1976  cores  temperature minimum  of  vertical breaking of  the  removal  highly  plastic  corers  The i n s i d e d i a m e t e r s  were  6.2,  6.6  r e s p e c t i v e l y . A l l c o r e s were s t o r e d i n a v e r t i c a l the  l o s s of  disturbance  the  cm,  c o r e b a s e . The b a r r e l - l e s s c o r e r u s e d i n 1977  utilized  the  loss  the  8  apparent  the v a l v e s e a l . This  at  2), in  i n t h e K u l l e n b e r g was 30 cm  s u r f a c e s e d i m e n t and t h e c o r e c o u l d be m a i n t a i n e d  sediment  some  and a Benthos  I n t h e Boomerang c o r e r , t h e e q u i v a l e n t d i s t a n c e i s and  p a r t of the  w i t h t h e c o r e r . T h r e e t y p e s were u s e d : a K u l l e n b e r g  1976,  The  and  at  12 °C,  - and were a l l o w e d s i x months.  The  the  1977  and  and  of  the  6.6  cm,  orientation .-  1979 c o r e s a t room  t o c o n s o l i d a t e and dewater f o r cores  were t h e n X - r a y e d ,  a  split,  1 30  photographed  5.1.1  Size  and  sampled  f o r s i z e and m e t a l a n a l y s e s .  Analysis  A f t e r manual h o m o g e n i z a t i o n , d i s s o l v e d f r o m 30-40 g ( d r y w e i g h t ) o f s e d i m e n t two the  0.5  h  a  coarse  t h r o u g h a 0.0625 mm units  are  diameter coarse  given  by  base  1  was  s i e v e d t h r o u g h 20.3 To  the  reduce  at the  1971  intervals.  split  diameters  and C a r v e r  in  phi  s p a c i n g was  (1971),  finer  the  a f t e r o v e n - d r y i n g a t 80-90 °C  intervals 0.5  p.50), the weights  The  phi  reciprocal  15  cm d i a m e t e r s i e v e s on a Ro-Tap f o r  0.25  by  by w e t - s e i v i n g  l o g a r i t h m of the  (1968)  in  the  3-4  p h i , and b e c a u s e  o v e r l a p i n the s i z e of the openings (Carver,  fraction  was  t h e r a t e of c l o g g i n g of the f i n e r meshes, t h e  were s p a c e d Otherwise  weighed  sediment  (Particle 2  i n mm- ). F o l l o w i n g F o l k fraction  (mud)  (4 p h i ) s i e v e .  removed  w a t e r , and d e c a n t i n g  centrifugation. This  ( s a n d ) and a f i n e  were  from the grab subsample  washes i n 70-80 ml of. d i s t i l l e d  supernatant a f t e r  into  salts  phi  determined  t h a n 4 p h i r e s i d u e was  min. sieves range.  of the p r o b a b l e  of meshes a t c l o s e r  were  and  at  spacings 0.5  phi  added t o the  fine  f r a c t ion. The  fine  fractions  by h y d r o m e t e r . Model.  5000  1977  grab samples  O t h e r w i s e t h e a n a l y s e s were r u n on  and  5000D  aqueous s o l u t i o n of dispersant  from the  and  Sedigraphs.  sodium  In  Micromeritics  either case, a 5 g  hexametaphosphate  s e t t l i n g medium. The  were a n a l y z e d  was  used  use o f 30-40 g o f  was  d i c t a t e d by t h e n e e d f o r s i g n i f i c a n t q u a n t i t i e s o f  in  the  sieves,  but  presented  N o r m a l l y o n l y 2 g of m a t e r i a l  a  problem  as  1~  1  a  sediment material  f o r the Sedigraph.  i n 25 ml o f d i s p e r s a n t  are  used,  131  which  would  have  meant  subsampling  the  i n t e r m e d i a t e s t e p and i t s a s s o c i a t e d designing entire  a  fine  fraction the  sample  mixing  fraction  cell  (Appendix  was d e t e r m i n e d a f t e r  water  loss  to  fine  errors  which  fraction. This  were  avoided  by  c o u l d accommodate t h e  4 ) . The  weight  of  the  fine  o v e n - d r y i n g a t 80-90 °C a n d u s i n g  correct  for  the  weight  of  sodium  hexametaphosphate. The which cell  adhered  magnetic  of  t o the magnetic  stir-bar  was  scrubbed  stir-bar  from  the  of m a g n e t i t e  i n the Sedigraph mixing  a n d t h e r e f o r e c o u l d n o t be r e l i a b l y  material  the  sediments c o n t a i n e d s i g n i f i c a n t q u a n t i t i e s  a n a l y z e d . Most of  mixture  by  stirring  this  with a  f o r 5 m i n . I t s d r y w e i g h t was a d d e d t o t h a t o f  analyzed fine  f r a c t i o n , o f w h i c h i t was 1-7%. The  precision  t h e s i z e d i s t r i b u t i o n s was ±2% i n t h e m e d i a n d i a m e t e r , ±3% i n  the  p e r c e n t sand  (diameters>0,0625  (0.002<diameters<0.0625 (diameters<0.002 samples 0.044  with mm  increased  mass  This  ±13%  in  the  7-38%  median  sand,  56-86%.silt,  diameters.  The  clay  precision  in  percent  clay  w i t h i n c r e a s i n g c l a y c o n t e n t and t h e o t h e r p e r c e n t a g e similarly.  maximum  of  method  was  samples  of the  small  s e v e r a l grams) of t h e s a m p l e s , t h e e n t i r e  was r u n on t h e S e d i g r a p h  from grab  percent  2.6-9% c l a y a n d 0.033-  g r a i n - s i z e a n a l y s i s .of t h e c o r e s , b e c a u s e  (a  sample  and  silt  mm), a s d e t e r m i n e d f r o m d u p l i c a t e a n a l y s e s o f 4  components behaved For  mm)  mm), ±1% i n t h e p e r c e n t  tested which  without  by a n a l y z i n g had  a  coarse-fine  split.  s m a l l amounts o f s e d i m e n t  already  been  analyzed  by  the  p r e v i o u s t e c h n i q u e . The r e s u l t s o f t h i s c o m p a r i s o n a r e p r e s e n t e d in  F i g . 43.  It  is  clear  that  the  two  techniques are not  1 32  e q u i v a l e n t . F o r samples w i t h median d i a m e t e r s mm,  both  the  substantially  median  diameter  and  the  greater  than  0.04  sand p e r c e n t a g e s  h i g h e r when t h e c o a r s e - f i n e s p l i t  are  i s used.  Seive & Sedigraph Median Diameter (yjm) F i g . 43. Sedigraph  Comparative size plus sieving.  Because  of  method y i e l d i n g the  the  effects  advantage  sedimentation  coarse-fine  analyses:  split  of  Sedigraph  versus  studying t u r b i d i t e s  diameters  was n o t u s e d  of.the coarse-fine s p l i t  alone  on  f o r both  sand  with a  and  mud,  f o r t h e c o r e a n a l y s e s . The the  size-distribution  are  p u r s u e d i n A p p e n d i x 4.  5.1.2 G r a i n The  Density  specific  gravity  of  several  s e d i m e n t s a m p l e s was d e t e r m i n e d u s i n g washed  sediment  following removed  the by  of  approximately  a n d a 500 ml v o l u m e t r i c  procedure  heating  outlined  by  Lambe  w h i l e under e v a c u a t i o n .  longer  formed  of s i l v e r  a white  nitrate  precipitate.  surficial 100  g  of  f l a s k as a pycnometer,  washed a n d c e n t r i f u g e d t h r e e t o f o u r t i m e s an a q u e o u s s o l u t i o n  t h e 1977  to  (1951).  A i r was  The s e d i m e n t s were  until the  the a d d i t i o n of supernatant  The method was  no  standardized  1 33  w i t h Ottawa sand, f o r which the v a l u e obtained  from  f o u r d e t e r m i n a t i o n s . The  v a l u e of the p e r c e n t a g e f i v e s a m p l e s was  5.1.3  and  d r y , unwashed s e d i m e n t was  brushed  through  a  a c i d and  nitric  approximately  t h e s a m p l e was Gelman  200  made  digested in  °C.  analyses  of  After  v i n y l membrane f i l t e r  on a T e c t r o n  AA4  E.V.  digest  Grill was  the  made  present be  and  D e p a r t m e n t of  evaporated,  nominal  pore  size  determinations  a t 386.0 nm  ml  were (oxy-  for  Fe  in  s e t of  due  Fe  s o l u t i o n s prepared  Oceanography.  12 s a m p l e s . The  A  by  blank  precision  of  2.7%±1.1% b a s e d upon d u p l i c a t e d i g e s t s of  to  i n the d i g e s t s but  l e s s than  acid  f i l t r a t e made up t o 100  f o r Cu and  10 s a m p l e s w i t h c o n c e n t r a t i o n s r a n g i n g errors  mm  parts  perchloric  a c i d had  Absorption  f r o m Cu  w i t h every  t h e c o n c e n t r a t i o n s was  Systematic  of . 4  range.  o f t h e UBC  run  solution  screen.  Atomic A b s o r p t i o n Spectrophotometer  10-30% a b s o r b a n c e were  0.005  and  water.  a c e t y l e n e f l a m e ) a t 324.8 nm  Standards  a  the n i t r i c  a  mortar  opening) nylon  1 part concentrated  washed t h r o u g h  with deionized d i s t i l l e d  by  absolute  ground i n a diamonite  140 mesh ( 0 . 1 0 5 mm  concentrated  to  duplicate  was  - 3  0.9%±0.1%.  g was  Dr.  average of the  d i f f e r e n c e from  A mass of a b o u t 0.5  the  2.64±0.02 g c m  Metal Analysis The  at  of  from  interference not  i n the  340  by  standards  to  990  chemical were  ppm.  species determined  3% by m e a s u r i n g t h e c h a n g e i n a b s o r b a n c e  induced  s p i k i n g a d i g e s t e d s a m p l e w i t h a known amount of t h e  element  from the s t a n d a r d  solution.  134  5.2 S u r f i c i a l 5.2.1  Sediments  Channelized During  the f i r s t  were s a m p l e d i n samples taken  and  from  rayed  c h a n n e l i z e d phase, t h e s u r f i c i a l  1977  the  only.  upper  t h e mine b o a t ,  and  stability  Regime  used  S a m p l e s were t a k e n  and The  t o a depth  then dropping long-channel The  are  Shipek  grab  10-15 cm o f 5-75 cm l o n g g r a v i t y  cores  and shear  relative  cores  were  strength tests  t o the channel  10-20 m f r o m  the sampler  X-  i n the  a x i s by l o w e r i n g  the bottom w h i l e  onto  under  the levee or channel  d i s t a n c e was d e t e r m i n e d  in  of  (1978).  r e s u l t s of the s i z e ,  summarized  consisted  t h e Mac I . The l o n g e r  f o r compaction  s t u d y by D a v i s  the sampler  These  sediments  specific  way  bottom.  by r a d a r .  g r a v i t y and  Cu  F i g . 44 a n d A p p e n d i x 5. T h e s e d a t a  h i g h e r Cu c o n c e n t r a t i o n s a n d g r a i n - s i z e a l o n g t h e  analyses indicate  channel  axis  and c l o s e t o t h e o u t f a l l . The and  specific  g r a v i t y h a s a mean v a l u e o f 2.82±0.05 g cm"  e x h i b i t s no t r e n d e i t h e r  exception  of  one  sample  s i g n i f i c a n t l y h i g h e r than is and  a  list Poling,  (Weast, grained and  p.  near  the  or  axially.  outfall,  t h a t of q u a r t z  1975), B-214).  together The  with  higher  With  (2.65 g c m " ) . Table  their  specific  the  these values are 3  of the p r i n c i p a l m i n e r a l s i n the t a i l i n g  sediments  other  laterally  3  specific  X  (from Evans gravities  g r a v i t y of t h e f i n e -  i s p r o b a b l y due t o t h e p r e s e n c e  of  i r o n - r i c h m i n e r a l s , a s d i s c u s s e d i n 5.2.4.  magnetite  2 8 8 T  •2.82 2.84  2.80* 2.87 T  Median Diameter,  um  Cu,  ppm  SG  F i g . 4 4 . S u r f i c i a l s e d i m e n t s , December 1977. ( a ) M e d i a n d i a m e t e r O/tm) ( b ) Cu c o n c e n t r a t i o n ( c ) S p e c i f i c g r a v i t y . The 1977 c h a n n e l a x i s i s i n d i c a t e d by t h e d a s h e d l i n e .  (ppm)  to tn  1 36  The c o m p a r a t i v e l y l o w e r s p e c i f i c grained a x i a l quartz This  sediments  augmented  concentrations chalcopyrite  by m a g n e t i t e a n d s u l p h i d e  i s consistent  of  copper  which  with  Percentage  and  50-70  2.65  25  2.72-2.94  2-20  with  bulk  and  (g cm" )  5-10  3  2.7 -3.3 2.6 -3.3  2-4  5.18  2-4 0.2 0.02 0.01  5.02 4.1 -4.3 3.9-4.1 4.62-4.73  water c o n t e n t ( r a t i o of the weight of water of t h e s u r f i c i a l  sediment  a mean o f 0.50±0.14 ( D a v i s ,  decreased with dry  (1975)  (1975)  the d r y sediment) 0.70  axial  2.65-2.68 2.63  2  Cargill  Poling  Grain density  1  The  higher  2  Silicates Quartz Carbonate Calcite Aluminum-oxides Feldspars Andesine Albite S h e e t - s i l i c a and C l a y Biotite Chlorite Iron oxide Magnetite Sulphides Pyr i t e Chalcopyrite Sphalerite Molybdenite 2  the  minerals.  (CuFeS ).  Mineral  '  coarser-  i s p r e s e n t i n t h e ore-body as  T a b l e X. T a i l i n g m i n e r a l o g y f r o m E v a n s C a r g i l l (1975).  1  of t h e  i s p r o b a b l y due t o g r e a t e r q u a n t i t i e s o f  slightly  interpretation  gravities  ranged  t o that of from  0.30-  1 9 7 8 ) . The w a t e r c o n t e n t  i n c r e a s i n g g r a i n s i z e . These v a l u e s c o r r e s p o n d t o  densities  of  0.96-1.54 g cm"  3  and  1.18 g cm"  3  r e s p e c t i v e l y , w h i c h n o t s u r p r i s i n g l y a r e somewhat l o w e r t h a n t h e value  o f 1.37 g cm"  the s p l i t  3  d e t e r m i n e d from t h e compacted sediments i n  cores (see Appendix 6 ) .  1 37  5.2.2  Surf i c i a l Extensive  in February in  Figs.  S e d i m e n t s : A p r o n Regime sampling  1979 45  f r o m t h e CSS  to  48  and  a s s o c i a t i o n of copper apparent. the  apron  flanks, by  deposit  Vector.  Appendix  with  Furthermore,  separated A  of t h e s u r f a c e  sediments  was  conducted  The  r e s u l t s are  summarized  5.  The  coarse-grained  coarser-grained  the  coarsest  of  copper-rich  s a n d was  deposits  noted  is  again  s e d i m e n t s were f o u n d  being  f i n e - g r a i n e d c o p p e r - p o o r mud  previously  on  the  along  present  west  on  flank,  the apron c r e s t .  at the  b a s e of  the  west f l a n k . These o b s e r v a t i o n s of the the  bathymetry i n Section  discharge  s c a r s and with  discharge The coarsest  result  of  Fine  4.4,  suggested  west  suggest  flank,  that  slumptogether  t h a t most o f  the  direction.  sediments i n  the  and  the h i g h e s t  also  the  sediment  diverted in this  were  interpretation  i n w h i c h i t was  c h a n n e l i z a t i o n of  contained  the  d e f l e c t e d down e i t h e r f l a n k . The  coarser-grained  was  There  present,  plume was  eventual  it's  time.  are c o n s i s t e n t with  Hankin  large  Point  area  were  both  copper c o n c e n t r a t i o n s  quantities  t h e e d g e s o f w h i c h were w e l l  of  rounded,  shell  at  the this  fragments  presumably  the  wear. tailing  was  present  i n a l l samples i n Holberg  Inlet.  Fig. 1979.  46.  Sand  content  (%)  of s u r f i c i a l  sediments  in  February,  1 39  F i g . 47. C l a y c o n t e n t 1979.  (%)  of s u r f i c i a l  Fig. 48. Cu c o n c e n t r a t i o n F e b r u a r y , 1979.  (ppm)  in  sediments  surficial  in  February,  sediments  in  1 40  5.2.3  Surficial The  Sediments:  sediments  w i t h i n and  sampled  from  sampling  m e t h o d s were  5.2.1,  with  sampling  along  markers,  and  the  Rechannelized  UBC  launch similar  the d i f f e r e n c e lines a  adjacent  Regime•  t o t h e new  (Appendix to  those  2)  channel  i n August  outlined  1979.  in  t h a t a s a m p l e l o c a t i o n was  defined  by  cross-angle  tethered measured  floats from  were  Section fixed  and  shore  The  by  shore with  a  theodolite. The in  r e s u l t s of the a n a l y s e s of these  Figs.  49  to  Fig.  a x i s and  presented  51 and A p p e n d i x 5. C o p p e r i s a g a i n a s s o c i a t e d  w i t h the c o a r s e - g r a i n e d sediments, channel  samples are  do  not e x h i b i t  which  are  confined  downstream-grading.  49. G r a b s a m p l e l o c a t i o n s , A u g u s t  1979.  to  the  141  Cu  concentration  (ppm) i n  surf i c i a l sediments,  August  142  5.2.4 S u r f i c i a l  S e d i m e n t s : Summary  Coarse-grained,  Cu-bearing  material  appears  to  c o n c e n t r a t e d a l o n g t h e c h a n n e l a x e s . The t r e n d t o s m a l l e r sizes  with  typical  increasing l a t e r a l distance  of deep-sea  Fig.  52  is  concentration  plot  in  of  the  the  1979  percent  samples,  1978b).  sand and  against  Cu  indicates  an  a p p r o x i m a t e l y l i n e a r d e p e n d e n c e o f t h e Cu c o n c e n t r a t i o n amount  of  sand  present.  The  the  average  background  level  m i n e w a s t e . The l o w e s t l e v e l s sediments  sampled  by  on  a v e r a g e Cu c o n c e n t r a t i o n  ( s a m p l e s c o n t a i n i n g no s a n d ) i s a b o u t  grain-  from t h e c h a n n e l a x i s i s  submarine c h a n n e l s (Normark, a  be  300 ppm,  and  the  i n mud  represents  of copper found i n the d e p o s i t e d  (60 ppm) were  found  in  g r a v i t y c o r i n g , as d i s c u s s e d  pre-mine  i n the next  section. a a  +  <=>-,  A A  A  03  +  + A  + •-ID  CO  AUG  79  -FEB  79  +  UJ CJC3  Q_ + A  A A,  fe 0.0  30.0  —i  COPPER  F i g . 52. P e r c e n t s a n d s u r f i c i a l sediments.  A  60.0  1  (PPM)  versus  1  120.0  90.0  Cu  (XI0  J  1  150.0  )  concentration  in  the  1979  143  Chalcopyrite flotation  is  ( E v a n s and  extracted  from  P o l i n g , 1 9 7 5 ) . The  the  host  rock  by  rock  i s m i l l e d to a  powder i n w a t e r . A f t e r a d d i n g s u i t a b l e s u r f a c e - a c t i v e air  i s b u b b l e d upwards t h r o u g h the  which  selectively  adheres  to  the  s u r f a c e . Presumably t h i s process particles  to  is  exceed  the  Point  winnowing of sediment  low  by  could  specific  relationship  be  currents. and  those  1 and  s u g g e s t s t h a t Cu  s a n d and  c o p p e r - p o o r mud.  character These plots  of  presented.  of  be This  with  the  the ore samples  percent  sand), being were  clay  and  the  coarse-  a x i s and  mud  due  in  to  the  from  the  i n the channel  are  i n the Hankin P o i n t  area  The  linear  t h e amount of  sand i n  behaves c o n s e r v a t i v e l y  of c o p p e r - r i c h  i n percent  and  d e t e r m i n e d by  than the probable  in  the channel  and  being  ±3%  would  values  S e c t i o n 4.5).  b e t w e e n Cu c o n c e n t r a t i o n  i s greater  surfaces,  bubble  currents  tailing,  i n Cu;  their  the  large  immersed w e i g h t .  minerals  surficial  data  for  further enriched  The  j e t (see C h a p t e r  s a m p l e ( F i g . 52)  the  along  gravity  a s s o c i a t e d w i t h the d i s c h a r g e  the  to the  the copper c o n c e n t r a t i o n  area  bottom  tidal  chalcopyrite,  efficient  particle's  g r a i n e d d e p o s i t s near the o u t f a l l , Hankin  chemicals,  sediments.  Once d i s c h a r g e d ,  w i t h the  less  fine  i s c a r r i e d to  a c c o u n t s f o r t h e a s s o c i a t i o n o f h i g h Cu  coarser-grained  the  bubbles,  f o r c e b i n d i n g the p a r t i c l e  likely  probably  the  w i t h s m a l l amounts of c h a l c o p y r i t e on  because the less  s l u r r y and  froth-  the  The  relative  scatter  amounts  in  these  e r r o r i n the measurements could  reflect  in  (±3%  variations in  the  processed. also and  A clear division  analyzed silt  exists  f o r Fe  against on  iron  and  in Fig.  content  a v e r a g e b e t w e e n low  53 are  clay,  1 44  Fe-poor and h i g h c l a y , F e - r i c h obvious  sediments.  i n the clay-sized material,  •data t h e c o n c e n t r a t i o n o f Fe a p p e a r s to  t h e amount  of  specific  gravity  bearing  minerals  silt  no  trend  within the scatter  is  of the  t o increase  i n proportion  present. This suggests  that the higher  o f t h e mud ( S e c t i o n like  Whereas  magnetite  5.2.1) or  i s due  pyrite  to  iron-  i n the s i l t - s i z e d  material.  +  +  + A  Jit  ^  +  * -FEB 79 +  + + *  h* +  +  + -tf  +  + A  +  A  A,  -AUG 79  A  cc  LQ_ U  '  •3  A l  3.0  —tS  A  +  +  'A. + + i  3.6  1 1 4.2 4.6 IRON (PERCENT)  ~i—  6.0  5.4  3.6  -1— 5.4  4.2 4.8 IRON (PERCENT)  F i g . 53. (a) P e r c e n t clay and (b) percent c o n c e n t r a t i o n i n t h e 1979 s u r f i c i a l s e d i m e n t s .  silt  6.0  versus  Fe  the presence  of  5.3 The S e d i m e n t Column The  cores  were  taken  t u r b i d i t e s and t h e frequency  to  establish  of occurrence of t u r b i d i t y c u r r e n t s  f r o m t h e number o f t u r b i d i t e s p e r u n i t the sediment A  accumulation  turbidite . i s a  length of core  vertically-graded single  current  1951).  (Kuenen. a n d M i g l i o r i n i , i n sedimentary  from  rate.  d e p o s i t e d d u r i n g t h e passage of a  found both  and  layer  of  surge-type  sediment turbidity  T h e s e l a y e r s h a v e been  r o c k s and i n marine  sediments ( e . g .  1 45  M i d d l e t o n a n d Hampton, 1 9 7 6 ) . T h e r e both  turbidites  and  turbidity  c o n c u r r e n t l y . One i n s t a n c e Ericson  and  surficial  Ewing  layer  microfossils earthquake.  (1954)  of  700  is  channels  a  have  been  identification 1 m  thick  i n which observed  by  Heezen,  vertically-graded  containing  shallow-water  km f r o m t h e e p i c e n t r e o f t h e 1929 G r a n d  Banks  T u r b i d i t e s h a v e been f o u n d a l o n g t h e a x e s a n d on t h e (e.g. Carlson  and  Nelson,  1969;  a n d K u l m , 1970; N e l s o n a n d K u l m , 1973) a n d s u b l a c u s t r i n e (Houbolt and J o n k e r ,  (Holtedahl,  1965; G i l b e r t ,  previously  in  experiments  have  shown  They  in  that  fjord  sought  deposits.  Flume  vertically-graded  (e.g. Middleton,  of a t u r b i d i t e  sediments  have n o t been  mine-tailing  surges  characteristics  1968), "and 1980).  subaqueous  d e p o s i t e d by t u r b i d i t y The  the  silt  l e v e e s of deep-sea c h a n n e l s Griggs  currents  of  graded  h a v e been few c a s e s  layers  are  1967).  (Bouma, 1962;  Middleton  and Hampton, 1976) a r e : (1) t h e l a y e r the t o p .  i s graded  from c o a r s e a t t h e base t o f i n e a t  (2) one o r more intervals below) i s p r e s e n t .  of  the  Bouma s e q u e n c e ( s e e  (3) t h e b a s a l c o n t a c t i s s h a r p a n d may e x h i b i t features indicating e r o s i o n and/or gravity loading of the underlying sediments. (4) t h e s e d i m e n t s i n t h e l a y e r are d i s t i n c t from and u s u a l l y c o a r s e r than t h o s e i m m e d i a t e l y above o r below. (5) t h e s e d i m e n t s i n t h e l a y e r c a n be i d e n t i f i e d source region i n shallower water. The  Bouma  labelled  sequence Ta,  Tb,  (Bouma, Tc,  Td  1962) and  comprises  five  Ta i n t e r v a l  i s u s u a l l y graded  intervals  T e ; Ta b e i n g t h e l o w e r m o s t  c o a r s e s t - g r a i n e d , Te t h e u p p e r m o s t a n d f i n e s t - g r a i n e d The  with a  and  interval.  w i t h t h e c o a r s e s t sediment a t  1 46  the  b a s e . The Tb a n d Td i n t e r v a l s  latter is  parallel  laminated,  b e i n g much t h e f i n e r - g r a i n e d . The i n t e r v e n i n g Tc  current  rarely  ripple-  or  i s not p o s s i b l e  satisfies  to  the  demonstrate  t r a i t s except  o c e a n , mud a n d s i l t classified The  role  layers thinner  played  has  at  turbidite  large  l a y e r s may be t o o t h i n  (4) a n d p e r h a p s  (e.g. P i p e r ,  every  p a r t i c u l a r l y a very thin  l a y e r of distances  to establish  ( 5 ) , so t h a t  t h a n 0.5  cm  i n t h e deep-  are  often  by  (changing)  bottom  currents  i n the deep  r e c e n t l y r e c e i v e d more a t t e n t i o n  been  identified  'contourites' currents the  ocean,  thin  1  by  currents  turbidites the  might  action  are t i d a l ,  a r e h i g h enough t h a t  resolved.  Difficulties  distinguish the  as  of  now  be  which called  contour-following  such changes  and the d e p o s i t i o n  semi-diurnal  are  to  be  or  ( s e e t h e r e v i e w by  (Heezen, H o l l i s t e r and Ruddiman, 1966). I n R u p e r t  ambient  yr~ )  - formed  not  i n the  Stow a n d L o v e l l , • 1 9 7 8 ) , a n d i t a p p e a r s t h a t some d e p o s i t s have  any  1978).  formation of c o a r s e - g r a i n e d l a y e r s thick,  that  l a i d down by a weak e v e n t o r  f r o m t h e main p a t h . Such  one a n d  a r e p r e s e n t i n a n y one t u r b i d i t e .  a l l five criteria,  fine material  the  interval  c o n v o l u t e - l a m i n a t e d . At l e a s t  a l l of these i n t e r v a l s  It  of  are  periodicity  expected  Inlet  rates might  (1 m be  i n attempting to  f r o m t h o s e i n t r o d u c e d by v a r i a b i l i t y i n  d i s c h a r g e , i n t h e o r e - t y p e , i n a c t i v i t y a t t h e w a s t e dump o r  i n t h e f r e q u e n c y and magnitude The  results  meandering  of slump-generated  from c o r e s taken from  channel  regime  along  the  levees  are presented i n d e t a i l  s e c t i o n , e m p h a s i z i n g the changes distance  the  flows.  in  channel a x i s .  the  sediment  during  the  i n the next column  with  B r i e f l y summarizing, coarse-  147  grained from  layers satisfying  criteria  1-5 were f o u n d i n  (4).  In  sufficiently  layers satisfied thick  conditions  layers, criteria  The  thicker  coarse-grained  the  within upper  surficial  sediments,  this  each  the  indicates a point  of o r i g i n  grounds,  i n the  Section  5.3.2,  briefly.  are  the  In Sections  used t o estimate  cores  from  5.3.3 t o  t h e apron regime a r e  5.3.5,  turbidity current  the  deposition  frequencies,  i n t e r v a l s between s m a l l - s c a l e laminae of p r o b a b l e t i d a l  are  the time of t r a n s i t i o n  t o the apron  The  possibility  e x i s t s that  the  result  disturbances  penetration and  basis  reach.  discussed  and  case.  Cu a n d l o w e r  m a t e r i a l . On  t h e c h a n n e l a n d t h e r e f o r e , on p h y s i c a l  In  rates  in  l a y e r s a l s o had h i g h e r  l e v e l s than the immediately adjacent  ( 3 ) and  ( 1 ) a n d ( 2 ) were  t e s t e d by g r a i n - s i z e a n a l y s i s a n d were s a t i s f i e d  of  cores  t h e m i d d l e a n d l o w e r r e a c h e s a n d n e a r t h e mouth o f H o l b e r g  Inlet. A l l coarse-grained  Fe  the  of  or  lower s e c t i o n s of the cores  core-catchers.  Disturbances  are  origin,  regime.  some o f t h e f e a t u r e s  subsequent h a n d l i n g  time  introduced  either  of the core. disturbed  described  by  during  Both t h e upper metal-finger  i n d u c e d by p i s t o n - c o r i n g i n b e d s o f  alternating  l a y e r s o f s a n d a n d mud have been d o c u m e n t e d by Bouma  and  (1968)  Boerma  primarily withdrawal normally  from  the  after occur  and  Stow  suction  incomplete-  and  Aksu  developed  (1977).  These  result  by  piston  during  penetration,  i n a gravity corer.  the which  would  not  148  5.3.1  The C h a n n e l i z e d The  locations  splitting  Regime of  the cores, l a y e r s of f i n e  thickness  from  less  than  5 5 ) . The c o a r s e - g r a i n e d of  the  thicker  deformation these  (A  casted  of t h e i r and  B)  the  ( F i g . 55;  silt  (Allen,  A,  at  ranging  of  darker.  and  F)  which  unstable  layer  of  are  found  or erosion  of  in  t o be f o r m e d plastic  unconsolidated  1970 p p . 8 2 - 8 6 ; M i d d l e t o n 1977 p p .  of  others to load-  l o a d i n g of a l i g h t e r  heavier  Some  Some  a n d Hampton,  198-201).  t h e b a s a l c o n t a c t o f F c o u l d a l s o be f l u t e  s u r f a c e by h i g h s p e e d  in  exhibited  contacts.  of which a r e thought  o r t o o l m a r k s due t o d e f o r m a t i o n  Fig.  silt  t o load-pockets;  1976 p p . 2 0 2 - 2 0 3 ; P o t t e r a n d P e t t i j o h n , structures  B  basal  ( F ) , both  t u r b i d i t e s , and both  and  sharp  are similar  l a y e r o f mud b y an o v e r l y i n g sand  and  0.1 cm up t o 20 cm were f o u n d ( F i g .  otherwise  gravitationally  sand  i n F i g . 54. On  l a y e r s i n these cores a r e  layers  flame-structures  lithified by  t h e 1976 c o r e s a r e shown  the  flow.  54. C o r e l o c a t i o n s a n d b a t h y m e t r y , November 1976.  The casts  underlying  F i g . 55. M o s a i c s o f some o f t h e h a l f - c o r e s f r o m N o v e m b e r , 1976. t h e s o l i d c i r c l e s on o p p o s i t e s i d e s o f a c o r e i d e n t i f y t h e l o c a t i o n o f a s p l i c e b e t w e e n two p h o t o g r a p h i c p r i n t s . 76-6 i s a q u a r t e r - c o r e . D i s t u r b a n c e s due t o s p l i t t i n g a r e p r e s e n t a t 5 cm i n 7 6 - 3 , 33-35 cm and 6 0 - 7 8 cm i n 7 6 - 4 , and 42 cm i n 7 6 - 8 . S l i g h t b r e a k s i n s a n d l a y e r s o c c u r a t 2 2 , 36 and 61 cm i n 6; 19 and 31 cm i n 7;and 2 cm i n 8. E was g o u g e d by m a t e r i a l a d h e r i n g t o t h e s p l i t t i n g w i r e . O t h e r labels are discussed in the text.  150  Upper R e a c h C o r e s 76-1  and  76-2  (Figs.  west l e v e e s of the upper primarily Cu  of  are  reach,  laminated  i n c r e a s e d w i t h depth coarser  than  56 and  silt  57)  and  s a n d , and  from core  laminae  50 cm  i n core The  is  not  beneath  observed i n the  Using  laminae  core  and  dark  levees  (Fig.  21)  thick,  which  is  induced  not  c o r e s . Some l a m i n a e  ( c o r e 2;  obtain  the  35-  slope. reach  tailing  a  by t i d a l  unlike may  56).  from the upper  to  2 and  (Fig.  the t h i c k n e s s of the  1  rough currents  thicknesses  represent  variability  discharge. bands of v a r y i n g shades of grey are  probably  main o r e - t y p e s  change  from  often inclined  of 3 m y r " , laminae  i n these  The thick)  mm  clear.  the  rate  2  w o u l d be  the c o n c e n t r a t i o n of  are present  of t h e l a m i n a t i o n s i n c o r e s  completely  deposition  and  and  consisted  1), p o s s i b l y r e p r e s e n t i n g the l o c a l bottom  origin  deposit  two  are u s u a l l y p a r a l l e l  Both  samples  1. B o t h  l i g h t bands encompassing s e v e r a l laminae The  from t h e e a s t  respectively.  i n e a c h c o r e . The  those  are  as  often  due  (2 cm  or  to d i f f e r e n c e s i n ore-type. There  i n the p i t , as  i n 76-1  every  2-4  and  that  w e e k s . One  being type  processed is a  more are can  green-grey  a n d e s i t e , the o t h e r a w h i t i s h - g r e y q u a r t z - f e l d s p a r porphyry.  The  other ore-types  are  primarily darken  are a l t e r a t i o n products  breccias.  the a n d e s i t e  Magnetite (Hillis,  of these  two,  and  a s s o c i a t e d w i t h the b r e c c i a s can  personal  communication).  151 76-1  (0-BOcm)  DIAMETER  COPPER 1050  F i g . 56. C o r e 7 6 - 1 , s h o w i n g m o s a i c o f t h e h a l f - c o r e a n d s i z e a n d Cu a n a l y s i s r e s u l t s . N o t e t h e l i g h t a n d d a r k b a n d s : l i g h t bands a r e a t 12-15, 2 8 - 3 8 , 48-52 a n d 58-60 cm d e p t h . F i n e r l a m i n a e a r e i n e a c h b a n d . The d o w n - t u r n i n g o f t h e l a m i n a e a t t h e e d g e s i s due t o f r i c t i o n a t t h e l i n e r w a l l d u r i n g penetration.  1 52  76-2 ( 0 - 80 cm ) CORE  20  —I  "5  COPPER (ppm)  DIAMETER 40  J  00  I  250  I  650  I  1050  I  10 H  I_ a  S  -  P 20 H  30  "I 40 H  L OU  50  60  70  Fig. 57. C o r e 7 6 - 2 . The d a r k v e r t i c a l s t r e a k i n t h e u p p e r 20 cm i s i r o n - o x i d e f o r m e d d u r i n g d e w a t e r i n g . The l i g h t s t r e a k s i n t h e l o w e r 30 cm were f o r m e d by m a t e r i a l a d h e r i n g to the s p l i t t i n g w i r e . N o t e i n c l i n e d l a m i n a e , a n d d i s t u r b a n c e i n u p p e r 10 cm.  1 53  Middle  Reach  C o r e s 3, 5 a n d 6 a r e f r o m t h e o u t e r meander  reach;  finer-grained banded  core  4  i s f u r t h e s t from t h e c h a n n e l .  than c o r e s  mud i n t e r b e d d e d  l e v e e s a t bends i n t h e  1 a n d 2, c o n s i s t i n g  of  with Cu-rich sand-silt  They a r e  laminated  layers with  and sharp  basal contacts. C o r e 4 ( F i g . 55) c o n t a i n s separated groups  coarse-grained  layers,  thinnest with  and  most  some c l o s e l y  widely  spaced i n  (D1-D3), and a sand c l a s t ( C ) .  C o r e 3 ( F i g . 55) c o n t a i n s 0.5 cm  the  and  less  in  frequent  thickness,  and  coarse-grained the thicker  layers  load-pockets  d i s c u s s e d p r e v i o u s l y (A a n d B ) . C o r e 5 i s f r o m t h e same bend b u t f u r t h e r 54)  and c o n t a i n s t h i c k e r c o a r s e - g r a i n e d  l a y e r s ( F i g . 5 5 ) . These  l a y e r s c o n s i s t of C u - r i c h ,  Fe-poor  median  f r o m 0.02-0.06 mm  diameters  ranging  Note t h e correspondence and  the darker  these  sand  and  (Figs.  silt  because  of  their  in  lower  d e n s i t i e s o f t h e s a n d a n d mud a r e v e r y  58 a n d 5 9 ) .  coarse-grained  layers  coarse-grained  porosity,  deposits  since the g r a i n  s i m i l a r . The p r e s e n c e  . d i f f e r e n t m i n e r a l s may a l s o have an e f f e c t . The l a y e r w i t h structures Fig.  of  iron-rich  cm d e p t h  layer and  i t s base  of  clay  (not v i s i b l e ) .  by  a  flame  mud w h i c h i s u n c o n f o r m a b l e w i t h t h e a d j a c e n t or mud-ball.  thin  A s a n d l a y e r a t 113-  ( F i g . 59, G i n F i g . 55) i s b o u n d e d by a 1 cm  may be a s a n d c l a s t  of  (F i n F i g . 55) i s a t 87-100 cm d e p t h i n  59. I t c o n s i s t s o f two g r a d e d l a y e r s s e p a r a t e d  layer 115  at  with  zones i n t h e X-ray p o s i t i v e . X-ray a b s o r p t i o n i n  sediments i s g e n e r a l l y higher  primarily  fine  between t h e dark  downstream ( F i g .  thick  laminae,  1 54  Fig.  58. C o r e 76-5, u p p e r h a l f . N o t e • d i s t u r b a n c e  i n top 8  cm.  1 55  76-5  (58-130 cm)  MEDIAN DIAMETER COPPER (^im)  (ppm)  IRON (%)  F i g . 59.- C o r e 7 6 - 5 , l o w e r h a l f . N o t e p o s s i b l e l o a d - c a s t e d s t r u c t u r e s a t 100 cm a n d m u d - b a l l a t 112-115 cm.  flame  1 56  Core 6 ( F i g s . The  dark  depth. and  61)  i s from  t h e o u t e r l e v e e a t bend  c o a r s e - g r a i n e d l a y e r s are t h i n n e r than  no d e f o r m a t i o n layers  60 and  are  of the b a s a l c o n t a c t  evident  in  analysis  61,  were  also  a b o v e and  75-76 cm),  easily  although  the  half-core.  l a y e r , and piece.  trend:  s e c t i o n c o u l d t h e n be  the sample s c r a p e d  Only  observed  This  very  minor  Cu  and  the  increases  i n t h e s e l a y e r s , and Enhanced  from  t h e Fe  low Fe  in  resolved  t o be  not  copper  levels  68-73 cm the  often  and  lower  particularly  86-92 cm). part  The  face  not  marked i n t h i s c o r e .  of t h e c o r e , a s  1 and  2 (Figs.  56 and  57).  from  of  the each  exhibit  can  the  changes  Furthermore,  be v e r y h i g h  i n t h e mud  also  a  i n most of  occur  i n c o r e 5 ( F i g . 5 9 ) . Cu  i n c r e a s i n g t o w a r d s t h e b a s e o f t h e c o r e were cores  sufficient  l e v e l s were o b s e r v e d  enhanced l e v e l s  size  c o n c e n t r a t i o n were  levels did  i n the f i n e - g r a i n e d sediments  by  separated along  the t h i c k e r c o a r s e - g r a i n e d l a y e r s t e s t e d , a l t h o u g h are  cm  visually  removed  exposed Cu  and  b e l o w 54  to obtain  s a m p l e t h e s e c t i o n c o n t a i n i n g t h e l a y e r had  5,  Unconformable  are r e a d i l y d i s t i n g u i s h e d both  X-radiograph (Fig.  present.  the X-radiograph  Thin l a y e r s which  on t h e  is  in core  4.  (at in  values  observed  in  1 57 76-6  (0-70 cm)  MEDIAN DIAMETER  l>m)  COPPER  (ppm)  IRON  (%)  Fig. 6 0 . Upper p a r t o f c o r e 76-6. N o t e t h e c h a n g e i n t h e s l o p e o f t h e l a m i n a e a t 54 cm.  159  Lower Reach Cores  7 and 8 a r e from the l e v e e s of the lower  9 from the Hankin Point area those  from the middle  most of the core thickest  (up  ( F i g . 54). In  ( F i g s . 55, 62 and 63). The sand  to  of  the  20 cm),  1976  contrast  reach, the c o a r s e - g r a i n e d l a y e r s  coarsest  0.063 mm) and have the h i g h e s t copper base)  marked  reach; core  cores.  (median levels  relatively  constant  diameters (>1200 ppm  7 f t  Sample  (.pm) 2 Q  to  a t the  Fe  levels  and i n c r e a s e only i n the mud. T h i s  MEDIAN DIAMETER  7  up  The d i s t r i b u t i o n of Cu through the  p a t t e r n i s c o n s i s t e n t with t h a t i n the s u r f a c e _ — — -  comprise  l a y e r s are the  coarse zones p a r a l l e l s that of the g r a i n - s i z e , while remain  to  4 Q  6 0 40  COPPER Q  (ppm)  ggg Q0 12  sediments. IRON  3.0  (%)  4.0 5.0  F i g . 62. Lower s e c t i o n of core 76-7. V e r t i c a l scale of the bargraph i s twice that of the photograph. The h o r i z o n t a l s c a l e s f o r Cu and Fe are d i f f e r e n t f o r t h i s c o r e . Note d i s t u r b e d basal s e c t i o n , and u n c l a s s i f i e d s t r u c t u r e at 27-28 cm. These  layers  are  vertically  graded  and have sharp basal  c o n t a c t s , and together with l a y e r F i n core 5 ( F i g s . 55 and are  the  59)  only examples of the Ta i n t e r v a l of the Bouma sequence  .1  verified by  by s i z e a n a l y s i s  thinner  i n t h e 1976 c o r e s . They a r e  o f t h e main s u r g e and background  or p e l l i t i c  i n t e r v a l . A sequence  layers  (Fig.  separated  l a y e r s o f mud r e p r e s e n t i n g m a t e r i a l d e p o s i t e d a f t e r  the passage  mud  60  d e p o s i t i o n - t h e Te  of a l t e r n a t i n g  silty-sand  i s p r e s e n t a t t h e t o p o f t h e Ta i n t e r v a l  and  i n core'9  6 2 , 7-16 cm) w h i c h may be t h e p a r a l l e l - l a m i n a t e d Tb a n d Tc  intervals.  No  characteristic 76 - 9  fore-set  bedding  or  convolute  laminae  o f t h e Tc i n t e r v a l a r e p r e s e n t . ( 0 - 38 cm)  MEDIAN DIAMETER (um)  •  CORF I  0  1  0-\  20 '  COPPER ( ppm)  40 1  60 250 |  650 '  IRON (%)  1050 3 I  5  1  7  *-  Fig. 63. Core 7 6 - 9 . N o t e Ta ( m a s s i v e , g r a d e d ) i n t e r v a l a t 1634 cm, a n d p o s s i b l e Tb a n d Td ( p a r a l l e l l a m i n a t e d ) i n t e r v a l s a t 8-16 cm. The  presence  of  a  turbidite  i n the Hankin Point area i s  compatible w i t h the time of year  (22 November) a t w h i c h t h e c o r e  was  amplitude  taken, since  tidal  i n autumn  the  c u r r e n t s s h o u l d be l o w e r b e c a u s e  of  the  near-bottom  of t h e p o s i t i v e  buoyancy  161  of t h e t i d a l  j e t (Section  1.2.1). F u r t h e r m o r e ,  weeks  t h e c o r e was  taken  after  ( F i g . 40a)  pronounced e r o s i o n e v i d e n t at other times Assuming the coarse l a y e r s then  these  cores  and  from  from t u r b i d i t y which  are  those  from  Scheidegger  and  Holberg  the middle  i n the  surges. This r e s u l t i n Chapter  the g e n e r a l l y accepted of  (Figs.  7  indicate  40b  the  and c ) . turbidites,  reach i n d i c a t e  importance  of  a  overbank  the c o n t i n u o u s d i s c h a r g e as compared w i t h t h a t  pursued  thickness  does not  i n cores 7 to 9 are  p r o g r e s s i v e down-channel d e c l i n e deposition  the bathymetry  8.  Potter,  important  implications  I t s h o u l d n o t be c o n f u s e d  downslope  individual  has  decrease  turbidites  in  with  grain-size  (e.g.  Walker,  and 1967;  1973).  Inlet  Cores penetrated  10 and  11 a r e f r o m H o l b e r g  the pre-mine sediment,  Inlet  which  was  ( F i g . 5 4 ) , and  both  c h a r a c t e r i z e d by  an  o l i v e - g r e e n c o l o u r , t h e o d o u r of h y d r o g e n s u l p h i d e gas  and  (<60  Detailed  ppm)  Cu  bathymetry  of  contoured  area  concentrations Holberg  Inlet  (Figs. is  i n F i g . 19, w h i c h  not  surveys  inlet  (data  (171 not  m at s t a t i o n  also 40a)  a cross-inlet w h i c h may  up H o l b e r g  10 and  10 and  of  very i r r e g u l a r .  118 m a t  11, w h i c h  t r a n s p o r t of m i n e t a i l i n g ridge immediately  west  p o i n t s of a s o u n d i n g  may  1 1 ) . The  the The line CSP  o f a mound o f f  a c t as a  barrier  u p - i n l e t . There  west o f H a n k i n  have impeded t h e p r o g r e s s of  Inlet.  65).  shown) i n d i c a t e t h e p r e s e n c e  C o a l H a r b o u r between c o r e s to the near-bottom  and  available  is itself  c o r e s i t e s were l o c a t e d a t t h e d e e p e s t a c r o s s the  64  low  is  Point (Fig.  turbidity  currents  162  76-  10  (0 - 55  cm)  CORE  MEDIAN DIAMETER  COPPER  (^im )  ( ppm )  20  M  40  60 250  I  650  IRON (% )  1050 3  5  20  o  Q_ LU D 30  Fig. lower  64. C o r e 76-10. N o t e m o t t l e s a n d h o l e s , p a r t i c u l a r l y i n h a l f , and dark pre-mine sediment a t base. Alternating  layers,  similar  present  only  turbidity  Cu-rich coarse-grained t o those  i n cores  i n the upper h a l f currents  had  Assuming t h a t t h e b e g i n n i n g represents  the  not of  commencement  and Fe-poor f i n e - g r a i n e d  7 and 8 ( F i g s .  of core  10 ( F i g . 6 4 ) ,  previously the  55 a n d 6 4 ) , a r e  tailing  of d i s c h a r g e  reached  indicating this  site.  at  52 cm  deposit i n October  1971, and  1 63  that  subsequent d e p o s i t i o n i s constant,  then the  onset  a l t e r n a t i n g c o a r s e - f i n e l a y e r s a t 27 cm o c c u r r e d 1974.  This  i s consistent  Hankin  Point  Carrying  d i d not  begin  the assumptions f u r t h e r ,  t h e 15-20 c o u n t a b l e  The  fact  and  that these  Scruton  bioturbation rate  turbidites  t i m e o f 43-64 d a y s f o r  events.  s e c t o r of t h e d e p o s i t Moore  beyond  17, 18 and 2 1 ) .  M o t t l e s a n d s m a l l h o l e s due t o b i o t u r b a t i o n 10.  indicate  tailing  1975 ( F i g s .  i n t h e u p p e r 27 cm g i v e a mean r e c u r r e n c e these  which  d e p o s i t s of  until  the  in March-April,  w i t h t h e CSP s u r v e y s  t h a t t h e development of s i g n i f i c a n t  of  holes are observed only  i s consistent (1957),  structures  who  increased  with  ( 0 - 30 cm)  with  DIAMETER 0  20  40  i n the d i s t a l  observations  of  decreasing  deposition  deltas. COPPER  ( pm ) CORE  the  core  found that the ' i n t e n s i t y ' of  i n submarine d e p o s i t s near r i v e r 76-11  permeate  IRON  ( ppm) 60 250  650  ( %) 1050  3  5  7  Fig. 65. C o r e 76-11. Note c o p p e r - and i r o n - p o o r dark pre-mine sediment e x t e n d i n g t o t h e base of t h e core ( a t 42 cm, n o t shown).  1 64  5.3.2  The  A p r o n Regime: C o r e s  Cores  were  taken  in  February  1979  with  Boomerang c o r e r a t t h e l o c a t i o n s i n d i c a t e d are t a b u l a t e d i n Appendix The  s u r f a c e s of the s p l i t  (79-4,  79-5,  from the e a s t  the  and  o f s a n d . 76-2 apron  although 50 and  76-6  are  cm).  79-7  i s from the  laminated  mud  C o r e s 79-10  t o 79-12  dominantly  laminated 79-11  overlying  and  beds  i s a t 55 cm  depth  latter  two  50 cm  down-inlet"  of  w i t h a 3 cm thick and  the thick bed  the is  above  terminating in w e s t of  of l a m i n a t e d  t h i c k were p r e s e n t  bed  i n 79-2  the  mud  (e.g.  apron,  and  o f s a n d a t 62  cm.  apron.  is  79-10  t u r b i d i t e a t 48 of  sand-silt  laminated layers. A 4  ( g r a v i t a t i o n a l l y ) deformed b a s a l  79-12.  of  l o c a t e d t o t h e e a s t and  lower  Only  s h o w n ) . 79-3  thick,  overlying a thick  have a  flank  not  of  mud  79-12  Results  o f l a m i n a t e d mud  t o 5 cm  of a l t e r n a t i n g mud  on  the  toe  are  turbidite with a  from  are p r i m a r i l y comprised  s a n d l a y e r s s e v e r a l cm  contains  thick  79-9,  s a n d l a y e r s up and  45.  c o r e s a r e shown i n F i g . 66.  c o n s i s t s of  f l a n k s , and  113  (H). Both  and  f l a n k and  a l t e r n a t i n g mud 15 cm  79-8  in Fig.  modified  5.  s h o r t c o r e s o f s a n d c o u l d be o b t a i n e d apron  the  cm mud cm  contact  FEBRUARY, 1979  CORES  F i g . 66. C o r e s from F e b r u a r y I979. Note t h a t d a r k e r c o l o r a t i o n i m p l i e s c o a r s e r m a t e r i a l e x c e p t f o r p r e - m i n e s e d i m e n t s i n d i c a t e d by t h e c r o s s - h a t c h i n g i n c o r e s I A - I C .  1 66  These the  cores r e i n f o r c e the sedimentation  surficial  that  sediments and t h e t r a n s i t i o n  coarser-grained  material  was  pattern  t o the apron  t h e west f l a n k s o f t h e a p r o n , a n d t h a t  material  was  channelized  phase.  disappearance cores, that  carried  of  The  coarse-grained  f a r down-inlet  latter  coarse  particularly  as  is  layers  regime:  d i v e r t e d down t h e e a s t a n d  primarily  not  i m p l i e d by  as  indicated  from  the  by  during the the  abrupt  upper p a r t s of t h e  7 9 - 7 , 79-11 a n d 79-12 (G1-G3, F i g . 6 6 ) . N o t e  the lower s e c t i o n s  o f c o r e s 79-11 a n d 79-12 a r e  comparable  i n a p p e a r a n c e t o t h e t u r b i d i t e beds i n 76-7 a n d 76-8 ( F i g . 5 5 ) . Cores  79-1A,  dump, a n d c o n t a i n  B  a n d C were t a k e n o f f t h e t o e o f t h e w a s t e  10-50 cm o f mine w a s t e o v e r l y i n g  g r e e n p r e - m i n e s e d i m e n t s . I n 79-1B, t h i s m a t e r i a l with  fine  waste,  interleave, material thin  implying  a  process  which  erodes  a n d m i x e s i t up i n t o t h a t b e i n g  5.5  is  olive-  interbedded  a n d i n c o r e 79-1C t h e two m a t e r i a l s a c t u a l l y  years  of o p e r a t i o n  the  deposited.  l a y e r o f m i n e m a t e r i a l was p r e s e n t s o  after  dark  close  underlying That such a  to  the  dump  i s s u r p r i s i n g , and s u g g e s t s  that  s l u m p i n g f r o m t h e w a s t e dump must be c a p a b l e o f d i s p l a c i n g q u a n t i t i e s of previously present  deposited  material observed  the  Turbidites  were  i n c o r e s 79-1A a n d 79-1B ( F i g . 66, A a n d B ) , t h e l a t t e r  e x h i b i t i n g pronounced deformation  waste  material.  large  in  these  layers  i n the t a i l i n g  deposit,  dump. The m a t e r i a l basis  of  concentrations, observed  i t s grading  i n these  was  the  visibly  lower coarser  contact. than  The  anything  a n d i s p r e s u m e d t o be f r o m  the  i s n o t d i s t i n g u i s h a b l e f r o m t a i l i n g on  Cu from  layers.  of  content,  however.  Similar  high  1466 ppm t o 279 ppm a t t h e t o p were  167  5.3.3 D e p o s i t i o n R a t e s : Deposition  Turbidity  rates  o b t a i n e d from  the diatom  assemblage w i t h depth  to  obtained  those  (Appendix  core  from  of t a i l i n g  sites  are  the seasonal v a r i a t i o n s  depth  and  are  in  thickness  Note  that  the  r e s o l v a b l e t h i c k n e s s i s 1-1.6 m, a n d t h a t a s p e e d 1500 m s "  in  1  the sediments  2, t h e i n c r e a s e i n t a i l i n g well  by a s t r a i g h t Table  XI  was a s s u m e d . E x c e p t  thickness i s  Counting  the coarse  thin,  and  coarse  layer  was  1976  assumed  l a y e r s becomes d i f f i c u l t  discounting the value from  recurrence i n t e r v a l  Rate  Interval  (m y r " ) 1  76-1 2 3 4 5 6 7 8 10  1.3-2.4 2.5-4.4 2.5 1 .2 2.2 2.0 4.0 1 .8 0.1  sound  at sites  of  1 and  reasonably  the  (cm)  15-90 15-150 10-125 25-75 82-140 8-45 5-60 0-27  cores. to  channel,  i n the channel  Number of Layers  24 44 49 1 1 49 17 57 1 5-20  turbidite.  turbidity  Number R e c u r r e n c e Density Interval (m- ) (d)  4.6 9.3 3.9 3.3 2.0 1 .9 43-64  and  turbidity  i s 2-5  1  very  reason  mean  vicinity  45.9 1 04.  this  when t h e y a r e  the  32.0 32.6 42.6 55.6  current  For  be a  f o r core 4 f o r t h i s  Table XI. Deposition r a t e s and p r o b a b l e r e c u r r e n c e i n t e r v a l s f r o m t h e 1976 c o r e s . Core  1976  minimum  t h e d e p o s i t i o n r a t e s and t u r b i d i t y  because i t i s f u r t h e s t current  of  represented  f r e q u e n c i e s a t t h e s i t e s of each of the every  site.  line.  lists  purpose  changes  time a t each of the  F i g . 67.  in  comparable  t h e r e f o r e be u s e d a t a n y c o r e  thickness versus  given  Frequencies  i n three cores  water  6 ) . The l a t t e r may  Plots  Current  days.  current  1972  1973  1974  1975  1976  TIME (year)  Fig.  67. T a i l i n g t h i c k n e s s , as d e r i v e d  1977  1972  1973  1974  1975  1976  1977  TIME (year)  f r o m CSP s u r v e y s , v e r s u s t i m e a t 1976 c o r e  sites. CTl CO  169  5.3.4  L a m i n a t i o n Time S c a l e The  76-2  probable  o r i g i n s of t h e l a m i n a t i o n s i n c o r e s 76-1  h a v e a l r e a d y been d i s c u s s e d  laminae  were  observed  a  h a l f - c o r e o f 79-6  thick  s l a b removed f r o m  a r e shown i n F i g . 68. V e r y  a r e a p p a r e n t on t h e X - r a d i o g r a p h w h e r e a s visible  on t h e  Using (Appendix  the  6 ) , the time s c a l e of  dark  i n t e r v a l s of  seems  15-19  likely  the  "fine  respectively,  h r and  o f 25%  in  17-22 the  which  i s pursued  is  79-6  shown  in  28  correspond to time  rate  estimate,  it  currents  7.  not  known  reach  of  8 ( F i g . 19) was  subsequently ( H i l l i s ,  personal  r a t e of 61 cm y r ~  1  the  p r e c i s e l y . A c c o r d i n g to the December  1977  A major change i n the a p p e a r a n c e of t h e  s o u n d i n g p r o f i l e a t ICM  a t G2  for  1  and c o n t a i n i n g  upper  s u r v e y s , i t o c c u r r e d b e t w e e n 23 1978.  _  t o t h e A p r o n Regime  bathymetric  transition  always  i n Chapter  channel  the d e p o s i t i o n  not  t o the e f f e c t s of t i d a l  meandering  persisted  laminae  hr between dark l a m i n a e . G i v e n a  time of the d i s a p p e a r a n c e of the  September  fine  structure  accumulation  t h a t t h e y a r e due  Transition The  surface  are  22.8-24.4 cm,  on d e p o s i t i o n . T h i s p o s s i b i l i t y  5.3.5  the  bands of d a r k l a m i n a e were c o u n t e d ,  18.9-22 cm and  laminae  possible error  they  finer  photograph  mean d e p o s t i o n r a t e o f 58 + 10 cm y r  each a t d e p t h s of 13  Much  surface.  F i g . 6 8 c a n be e s t i m a t e d . Two  and  5.3.1).  i n some o f t h e o t h e r c o r e s . A  and X - r a d i o g r a p h o f a 1 cm of  (Section  and  observed  c l o s e t o t h e t i m e of the change o b s e r v e d  monthly 1978  communication).  f o r 79-11  o c c u r r e d n e a r 23 May,  i n May  from Appendix  1978.  and  and  Using 6,  the  This i s acceptably  i n ICM  8, and  to  that  1 70  extent  confirms  this interpretation  of the G t r a n s i t i o n i n t h e  8H  E  o  X»- 18 H CL 111 Q  28  H  F i g . 68. P h o t o g r a p h ( l e f t ) and X-radiograph (right) of 1 cm thick slab from core 79-6. N o t e c o n g r u e n c e i n s h a d e s o f g r e y b e t w e e n t h e two p r i n t s , and t h e v e r y fine laminae i n the Xradiograph.  171  CHAPTER 6 CURRENT MEASUREMENTS 6.1 T a u t - W i r e M o o r i n g s : M e a n d e r i n g C h a n n e l Regime A a n d e r a a RCM4 c u r r e n t m e t e r s moorings at  with subsurface f l o t a t i o n  stations  bathymetry  76/1 i s also  August mooring  and  76/2  shown.  were  deployed  taut-wire  i n A u g u s t a n d November, 1976  ( F i g . 6 9 ) . The The  on  November  1976  bathymetry a t the time of the  i s unknown.  F i g . 6 9 . 1976 m o o r i n g l o c a t i o n s , p l u s s t a t i o n J ( l o c a t i o n o f Run 2 from J o h n s o n , 1974).  6.1.1  A u g u s t 1976 The r e c o r d s f r o m t h e  two  meters  on  the  August  mooring  (76/1) a r e shown  i n F i g . 7 0 . The m e t e r s were 3 a n d 13 m f r o m t h e  bottom  m w a t e r d e p t h , a n d t h e s a m p l i n g i n t e r v a l was 10  min.  at  124  CM98H bottom • 3m  CNI73I bottom* 13m a  Q. a 1  1  1  1  1  r  ~t  1  a-  ~t  1  r  -i  1  1  1  "1  1  1  1  1  r  1 1  T  1  1.0  1  1 1 1 2.0 TIME(DAYS)  1.5  1  ri  2.'  1  CM73I bottom»13m  —r— 1.0  i 1.5  1 1— 2.0 TI MEIDRYS1  —l— 2.5  -i— L.O  —l  1 r— 2.0 TIMEIOAYS)  1.5  F i g . 7 0 . C u r r e n t meter r e c o r d s a t 7 6 / 1 , 24-26 August 1976. (a) T e m p e r a t u r e , s a l i n i t y , p r e s s u r e and p r e d i c t e d t i d e s ( d o t s ) , d i r e c t i o n ( - 1 8 0 ° = d o w n - i n I e t ) a n d s p e e d , ( b ) A x i a l ( u ) a n d c r o s s i n l e t ( v ) v e l o c i t y c o m p o n e n t s r e l a t i v e t o an u p - i n l e t d i r e c t i o n o f 70° t r u e . T i m e 0 i s 0 h P D T , 24 A u g u s t 1 9 7 6 .  173  The  currents  t i d e , except the  were  f o r two  down-inlet  u p - i n l e t flows at the  r e c o r d . T h e s e a p p e a r t o be  ranges,  and  water. For inlet  reversed  the  were  flood  beginning  to down-inlet  record,  associated  minimum with  flood  end  or at  maximum and  of  flood tide  before  and  (rising)  and  associated with higher  direction  r e s t of t h e  speeds  even d u r i n g  high down-  ebb  tides,  respectively.  while  Temperature  increased  salinity  d e c r e a s e d . The  suspended- t a i l i n g ( S t u c c h i and  6.1.2  125  and  (Fig.  69).  speed  suspected clear  l a t t e r may  to  a f f e c t " the  72 a r e The  the  sampling  cm  s' )  by after  1  that t a i l i n g  to  periods  reversals  real,  since  the  sensor  from the mooring at  station  the the  to  trend  decreases  m o t i o n . Toward t h e end  third  lower  followed of  the  day  remained  before during  i t is it  flood  tide.  periods events  and  the Five  a t or s h o r t l y a f t e r  5  is  down-inlet.  h i g h w a t e r . Of  temperatures,  these  below  ( F i g . 7 1 ) , and Nevertheless,  record, these  an a c c e l e r a t e d r a t e of c o o l i n g .  min.  o f t h e c u r r e n t was  occurred  to  20  meter  rotor.  16 were  u p - i n l e t ' flow a  lower  flow occurred  of u p - i n l e t f l o w ,  45 m f r o m t h e b o t t o m a t  i n t e r v a l was  f o u l e d the  down-inlet  water. There i s temperature  be  record,,  conductivity  m e t e r s were 6 and  recorded  (1.5  records  t h a t the dominant d i r e c t i o n  Reversal  not  the  1976).  m w a t e r d e p t h . The  threshold  throughout  1976  F i g s . 71  The  21  Farmer,  November  76/2  appear  gradually  high  abrupt  of u p - i n l e t resulted  in  o  in J i u>  in  oi  1  1  1  1  1  1  I  1  I  I  ; I  1  1  1  1  I  1  1—:—I  I  1  1  a  0.0  1.0  2.0  3.0  4.0  S.O  6.0  TIME(DAYS)  7.0  8.0  9.0  10.0  11.0  F i g . 7 1 . R e c o r d f r o m l o w e r m e t e r a t 7 6 / 2 , w i t h t h e p r e d i c t e d t i d e . Up-inIet=0°. T i m e 0 i s 0 h P S T , 20 November 1976. The u and v c o m p o n e n t s a r e p a r a i l e i t o a n d t r a n s v e r s e t o t h e i n l e t a x i s , r e s p e c t i v e l y . R e c o r d e d s p e e d . i s z e r o f o r most o f t h e r e c o r d due t o r o t o r f o u l i n g (see t e x t ) .  1  E o °"  E 3  a CO in ~i  1  i  r  1  r  1  -  1  S.O 6.0 TIME (DATS) F i g . 72. Record are p l o t t e d .  from upper meter a t  76/2. Axial  (u)  T"  n  1  r  -i  1  r  r  and t r a n s v e r s e  (v)  velocity  components  cn  1 76  Rotor meter  fouling  i s not  ( F i g . 7 2 ) . The  periods these  (29)  19 t o o k  water.  The  of  occurred duration  high  residual  f l o w was  flow reversed maximum  slack.  flood  r e c o r d from the  also down-inlet,  tide,  to down-inlet down-inlet  Reversal  10 t i m e s . A l t h o u g h of  i n the  usually  but  close  speed  was  reached  at  t o u p - i n l e t f l o w d u r i n g ebb  the temperature decreased  f r e q u e n t l y or at the  deeper meter. N e v e r t h e l e s s ,  to  a b o u t midway t h r o u g h  the mooring a t t h i s d e p t h as w e l l ,  d i d not d r o p e i t h e r as  the decreases  the  73. V e s s e l m o o r i n g s t a t i o n s ,  over  more  were  as a t  associated  Scale In feet S e p t e m b e r 1978.  low the or tide the  temperature  same t i m e s  p e r i o d s of u p - i n l e t m o t i o n .  Fig.  upper  s u s t a i n e d u p - i n l e t m o t i o n were r e g i s t e r e d . Of  place during  f l o o d t i d e , and before  apparent  the with  1 77  6.2 O v e r - t h e - S i d e In  C u r r e n t M e a s u r e m e n t s : A p r o n Regime  September  1978, m e a s u r e m e n t s  were made w i t h A a n d e r a a  RCM-4 m e t e r s s u s p e n d e d b e l o w a f o r e - a n d - a f t moored v e s s e l w i t h a 136  kg l e a d w e i g h t  a t a d i s t a n c e above t h e bottom d e t e r m i n e d  an ORE M o d e l 150B 11 kHz p i n g e r Fig.  by  (see Appendix 7 ) .  73 shows t h e f o r e - a n d - a f t m o o r i n g s t a t i o n s . N o t e t h a t  the meandering submarine channel  had d i s a p p e a r e d  by  this  time.  T h r e e m e t e r s were s u s p e n d e d a t a p p r o x i m a t e d i s t a n c e s o f 2, 4 a n d 7  m  from  the  bottom.  The  p o s i t i o n s were r e c o r d e d  every  positioning  Ship  system.  sampling 2 to 5  interval  jmin  was 2 m i n . S h i p  from  velocities  the  computed  Trisponder from  p o s i t i o n s were s u b t r a c t e d f r o m t h e m e a s u r e d c u r r e n t  these  velocities.  T h e s e d a t a , w h i c h a r e s u m m a r i z e d i n A p p e n d i x 7, may be only  near-bottom  cycle  from a s h i p a t a m u l t i p l e - p o i n t mooring i n  data  current  measurements  f r o m s t a t i o n 78/2 a r e p r e s e n t e d  records  represent  periods  when  transfer  the pinger  f o ra hydrocast.  records  (z) represent  the  meters  The s t e p s  water  and  salinity  and temperature  decreased  0.2 °C a n d 0.05-0.2 p p t b e t w e e n change origin inlet  current  7 ) . The d i r e c t i o n  (72°) o r d o w n - i n l e t  ( 170°)  at  15.25  fjord.  The  in  the wire  to  pressure length to  related  to direction  the  next  rather  chapter.  t h e b o t t o m by 0.0-  meters.  The  salinity  of as y e t undetermined either  up-  (252°), e x c e p t i n g t h e c r o s s - i n l e t  flow  d.. T h i s  was  raised  Some  toward  i s d o m i n a t e d by a 0.2 p p t o f f s e t (Appendix  a tidal  depth.  r e v e r s a l s a r e p r e s e n t , and a r e d i s c u s s e d i n Temperature  a  were  changes i n t h e overboard  changes i n s a l i n i t y  over  i n F i g . 74. The g a p s i n t h e  compensate f o r the t i d a l changes i n abrupt  obtained  the  change  dominantly  follows  t h e p a s s a g e o f an  1  acoustically-detected The motion The  axial  residual  inlet to  flow  cm  similar  s  those and  0  to  The were  5  best  -  about  ship the  lateral Wind  1  motion  F i g . 76. motion  evident. sudden  suspended flow.  i s reasonably velocities  and from  5 t o 2 0 cm  moorings  measurements periods  anchor,  75.  to up-inlet  flow  transition  to  down-  down-inlet  flow  close  except 78/4  consistent ranged s"  ranged  with  with  from  from  the  -20 t o -  up-inlet,  1  the  o f low or z e r o  only  The  during  The a b r u p t  at  78/4,  increase  whereas  - 7 t o - 1 5 cm s "  had  drop  record casts  a  1  speeds.  Wind-  the shorter two  itself  yaw  scope,  and  minutes. as  20-40°  (Appendix 7 ) . at station  78/2 are p l o t t e d  a t mid-depth  before  flow.  usually  method  combination  ebb and e a r l y  in salinity  also  wind  period of  in salinity  to down-inlet  overboard  and manifested  predicted late  particulate  of  an approximate  of the b o t t l e  reversal  using  which  i n the direction  results  ship  in Fig.  at a l l stations  consisted primarily  translation  The  a n d maximum  Maximum  during  forward  fluctuations  Transition  with  .  was a p r o b l e m  inlet  pattern  current  obtained  induced  the predicted tide  p a t t e r n was o b s e r v e d  the taut-wire cm s  of v e l o c i t y ,  water.  down-inlet  from  with  to mid-flood,  results.  1  (Chapter 7 ) .  components  was d o w n - i n l e t .  7 ) , which  _  surge  o r a t p r e d i c t e d low water,  close  taut-wire  the  flow  predicted high  (Appendix  in  are plotted  before  A  40  and c r o s s - i n l e t  removed,  occurred  turbidity  78  high  The  dropped  flood tide  due t o upi s  quite  i s due t o  concentration during  of  down-inlet  r  i  o  (If*" M  1  " 1  1  I  i—i  I  o O-  T  i  r  _  ~1  r  Ol  1  i  i  i  i  i  i  r  1  m cn  r r - i p  CL  m  Q_  lu cn  L_l L_J  li  fi  ~1 15  0  TIMEiDRYS)  15.25  —i——i  1 14  5  1 4 . 7 5  1  15.0  TIME(DAYS)  1—1* 1 5 . 2 5  14.5  14.  /5  15  R  J  Y  I5.L.'5  TIME(DAYS)  F i g . 7 4 . C u r r e n t m e t e r r e c o r d s a t f o r e - a n d - a f t m o o r i n g s t a t i o n 78/2 a n d p r e d i c t e d t i d e on 14-15 S e p t e m b e r , 1978. A r r o w s i n d i c a t e 0330 h and 0525 h PST. N o t e t h e a b s e n c e o f m a j o r h i g h f r e q u e n c y f l u c t u a t i o n s i n t h e d i r e c t i o n r e c o r d s . U p - i n l e t i s 72° t r u e . The p r e s s u r e s e n s o r on t h e BOTTOM meter m a l f u n c t i o n e d d u r i n g t h e f i r s t p a r t o f t h e second c a s t .  a CO  o.  C_)  CD  o.  -fM  CO  i  CJ  r?  1  i  o CO  >-  -A CD  co r\j  i  CD fM CO  X o fM  CD .  LO  14.5  14.75 15.0 TI ME ( D A Y S )  15.25  14.5  14.75 15,0 TIME (DAYS)  F i g . 7 5 . ( a ) T r a n s v e r s e ( v ) a n d a x i a l ( u ) c o m p o n e n t s o f v e l o c i t y a t 78/2 w i t h removed. X and Y a r e e a s t - w e s t a n d n o r t h - s o u t h d i s p l a c e m e n t s o f t h e s h i p .  15.25  1  s h i p motion (b)  181  SEPTEMBER 1978  Station 2  TIME (days) .  F i g . 76. C o n t o u r p l o t s 78/2.  of s a l i n i t y  and suspended  particulate  at  182  6.3 I n t e r p r e t a t i o n These c u r r e n t meter r e c o r d s those  obtained  by J o h n s o n  July  strong  mooring  are  a n d December, 1973.  reproduced  cm s "  presented  down-inlet  1  amplitude  and  (Johnson,  F i g . 77. E x c e p t  flood.  are similar with  high  i n conjunction  water and  velocities  of  up-inlet.  1  f o r the  i n amplitude  maximum  10-30 cm s"  from  with  The the  high waning  1974) a n d a p p e a r t o be s u p p r e s s e d when t h e  range of t h e immediately the  earlier,  u p - i n l e t flows occur  spring tide  with  data  1  phase t o those  of  in  The  (70 cm s " ) u p - i n l e t c u r r e n t s n e a r p r e d i c t e d  toward t h e end of t h e r e c o r d , these  -40  agreement  (1974) a t 1 t o 1.5 m f r o m t h e b o t t o m  i n J u l y , O c t o b e r , November the  are i n general  preceding  Reversal  water i s a l s o present  ebb i s much g r e a t e r  than  that  t o headward motion near p r e d i c t e d  high  i n the record  from t h e lower  m e t e r a t 76/2  (Fig. 71). Fig.  78  amplitude deep  and  water  schematic  phase  based  explanation density  is a  can  field  relaxation  of  be  the  made  vertical  two  in  response  data  sets.  to  mixing  the  induced  earlier  tide  (1973),  could  extended  that  forcing  given  and  j e t . I ti s by  Johnson  suggestions  by ( a )  t h a t d e e p - w a t e r movement u p - i n l e t d u r i n g  occur  as  a  result  of a readjustment of  gradients  f o l l o w i n g p e n e t r a t i o n of t h e t i d a l  and  by  (b)  qualitative  by t h e t i d a l  (1974,  Drinkwater  unusual  regime i n t h e  A  alternate  of  who  the  terms of t h e readjustment of t h e  essentially a further modification pp. ' 77-83)  of  r e l a t i o n s h i p of t h e c u r r e n t  upon  in  representation  Lazier  (1963),  j e t to  motion  pressure  mid-depth,  that a mid-water p e n e t r a t i o n  f l o o d - t i d e could d r i v e down-inlet  ebb  during  i n t h e deep w a t e r .  5(H  Fig. July  77. A x i a l c o m p o n e n t o f v e l o c i t y a t s t a t i o n J ( F i g . 6 9 ) a t 1.0-1.5 m f r o m t h e b o t t o m i n 1973. T i d a l e x t r e m a a r e t h o s e p r e d i c t e d f o r C o a l H a r b o u r ( a d a p t e d f r o m J o h n s o n , 1 9 7 4 ) .  CD CO  1  i  84  r  Up-lnlet  i i  1•  i  1  i • —  Down-Inlet  F i g . 78. S c h e m a t i c r e p r e s e n t a t i o n o f a x i a l v e l o c i t y component i n the deep w a t e r as a f u n c t i o n of t h e phase and range of t h e t i d e . During water  flood tide,  outflow  from  the  t u r b u l e n t m i x i n g about water  at  full  Marble  j e t plunges beneath the River,  the core of the  producing  jet  at  a  fresh zone  The  i n t r o d u c e d by t h e j e t must l e a v e t h e m i x i n g zone and  flow  isopycnals.  the v e r t i c a l  p e n e t r a t i o n of the j e t i s o n l y t o  f l o o d , a down-inlet flow  i n the deep water  is  mid-depth generated  by a c o m b i n a t i o n o f t h e e n t r a i n m e n t o f d e e p - w a t e r  a t t h e base  the  jet  to the  flux  of water If  water  of  mid-depth.  headward a l o n g If  the t i d a l  and  t h e headward flow a t mid-depth  outward  from the m i x i n g r e g i o n .  the j e t i s s u f f i c i e n t l y will  due  of  occur  i n the l a t t e r  dense, half  penetration of the f l o o d  into (Stucchi  deep and  185  Farmer, inlet  1976), r e s u l t i n g  i n a r e v e r s a l to (along  f l o w n e a r h i g h w a t e r . The  isopycnal)  d e p t h o f p e n e t r a t i o n d e p e n d s on -  b o t h t h e d e n s i t y and momentum o f t h e j e t ( S t u c c h i , increase  with  preceding  ebb  t i d e may the  the  flood  remain below  suppression  the  t h e n an  ebb  d e n s i t y of t h e j e t exceeds flow  similar  would  outflow  over  isopycnal half  full  ebb,  the  due  Thus tailing  also  upward  the  causes  towards  possible  not  where pj = 2.8  g cm"  ambient  concentration  explain  antecedent  3  deep-water,  by  changes  unlike  filled  that  to  a  the  inclination  the  an  the s i l l .  of  During the l a t t e r  decreases,  the  d r i v e s a headward  m a t t e r i n mg  of  pressure  flow.  the  suspended  For a given  litre  -  1  ,  mass  the excess  is  - 3  fe)MxlQ-  6  water.  record  by t h e j e t .  = 6.4x10"  7  M  (6.1)  i s t h e g r a i n d e n s i t y and p„ i s sea  in  gradient driving  contribution  (M) o f s u s p e n d e d  Ap = ( pj-  the  slope  field  d e n s i t y of the m i x t u r e i n g c m  of  is  t o t h e d e n s i t y f i e l d has been i g n o r e d .  concentration  flood  ( F i g . 71).  balloon being  to the d e n s i t y  far,  accompanied  flood tide  o f t h e ebb, a s t h e s u r f a c e  gradient  during  t h a t of the  the s u r f a c e p r e s s u r e  sill  surfaces  be  a t 76/-2  l e a k y but e l a s t i c  During  density  t o t h o s e o b s e r v e d a t t h e end o f t h e  response d u r i n g  slightly  the  i f the range of the  t h a t of the deep w a t e r . T h i s would  from t h e n e a r - b o t t o m meter The  great,  Both  tide.  up-inlet  temperature  range, but  1980).  o f t h e h i g h w a t e r u p - i n l e t f l o w by an  large-amplitude If  tide  is sufficiently  up-  Referring  of p a r t i c u l a t e sometimes r e a c h e d  to  the  Fig.  100 mg  density 76, • t h e  litre"  1  at  186  1-2  m from the  0.06  bottom. T h i s corresponds t o a d e n s i t y  sigma-t u n i t s ,  especially salinity  certainly  considering that at t h i s s t a t i o n were  only  temperatures). bottom  w h i c h i s s m a l l but  ±0.1  ppt  Nevertheless,  (±0.1  at  tidal  changes i n  units  10-20  data  instrument  the  i n l e t ( F i g . 6 9 ) , where t h e a x i a l d e p t h o f t h e at  the  time.  I  doubt  that  this  location The  shear  near-bottom smoothed  continuous  at  78/2,  running together  during  periods  velocity t h e end  gradient of the  down-inlet the (Fig.  of  r e c o r d , and  f l o w , t h e r e was  velocity  vector  80). This  increase attributed  occurred  in  to  leftward  are  from the  slope  field  either  at  evidence  Fig.  79  shows  from the  records.  bottom,  left  rotation  speed toward the  as of  the the  bottom d u r i n g  to a discharge-driven  density  a the  three  The  speed  particularly  flow. A reversal  in  of  Chapter  in  the  flow  at  7.  During  an a p p a r e n t s h i f t i n t h e d i r e c t i o n the  of 150  solids  t h e p e r i o d of u p - i n l e t  i s discussed  from  were e x a m i n e d f o r  as  w i t h the d i r e c t i o n  during  quickly  76/2.  current.  moderate d o w n - i n l e t  the  i n l e t was  measured  average) speed r e c o r d s  tended to decrease with d i s t a n c e  these  from  south  suspended  direction  turbidity  m  the  c u r r e n t meter r e c o r d s  i n b o t h s p e e d and  (5-point  m on  currents  the upper meter at  over-the-side  vertical  meters  o r by  108  the  c o n t r i b u t e d s i g n i f i c a n t l y t o the  at  i n F i g . 77  an  m  moored a t a d e p t h o f  negligible,  of suspended m a t t e r  s m a l l v a l u e s . The  of  not  sigma-t  distances  ( F i g . 76), the c o n c e n t r a t i o n  drops to n e g l i g i b l y  the  excess  of  bottom i s approached velocity down-inlet  current.  and  the  flow  are  187  Q  CJ UJ CO CJ  o  CL CO  TOP  CO  CD LU  a I  CO MIDDLE  CO  -J  !  CD. o CD CO  CO _ J  0*"  14.5  BOTTOM  14.75  •  15.0  15.25  TIME(DAYS)  F i g . 79. C u r r e n t d i r e c t i o n and smoothed speed from a l l t h r e e meters a n d t h e p r e d i c t e d t i d e a t s t a t i o n 7 8 / 2 , S e p t e m b e r 14-15 1978. A d i r e c t i o n o f 72° i s u p - i n l e t .  F i g . 8 0 . A x i a l (u) and t r a n s v e r s e ( v ) c o m p o n e n t s o f v e l o c i t y , c o r r e c t e d f o r s h i p m o t i o n , a t e a c h o f t h e t h r e e m e t e r s a t 7 8 / 2 on 14-15 S e p t e m b e r , 1 9 7 8 .  CD CO  189  CHAPTER 7 THE  ACOUSTICAL CHARACTER OF THE AND  I d e a l l y , an include  TURBIDITY SURGES  observation  estimates  of  of  t i m e s of passage  path.  As  so  presented almost to  exclusively  turbidity  current  should  i n the c a s e of s u r g e - t y p e  stated 1,  by Normark  such  (1978)  observations  i n the  have  flows,  quotation  been  limited  to laboratory experiments. This i s testimony  the d i f f i c u l t i e s a s s o c i a t e d w i t h m o n i t o r i n g such  and p o t e n t i a l l y d e s t r u c t i v e  intermittent  phenomena.  N e v e r t h e l e s s , a number o f i m p o r t a n t o b s e r v a t i o n s h a v e made.  Inman  turbidity  et  al  currents  (1976)  up  to  2.5  storms, a f t e r deposit canyon  h.  i n La J o l l a  These  Canyon  with  maximum  of up t o 190 cm  were  s  _ 1  head  and  durations  that  the  c u r r e n t meter Marshall  also  r e c o r d s from  (1973;  La  McLoughlin  (1975;  McLoughlin  and  c a n y o n s ) . I n two observed  have  Sullivan  been  submarine  Jolla  Rio  sand  storms u n t i l  t i m e as t h e s e d e p o s i t s were r e g e n e r a t e d . S u r g e s p r e s u m e d currents  of  had been removed. F u r t h e r m o r e , down-  s u r g e s were n o t g e n e r a t e d by s u b s e q u e n t  turbidity  to  velocities  a s s o c i a t e d w i t h the passage  w h i c h o b s e r v a t i o n by SCUBA showed  i n the canyon  been  have r e p o r t e d e v e n t s a t t r i b u t e d  ( r e g i s t e r e d by c u r r e n t m e t e r s ) of  flow  of the surge a t s u c c e s s i v e p o i n t s a l o n g i t s  aptly  i n Chapter  a  the f o l l o w i n g parameters: v e l o c i t y ,  t h i c k n e s s , e x c e s s d e n s i t y and, the  DISCHARGE PLUME  observed canyons  Canyon),  Balsas  o f t h e s e , La J o l l a  Rio  by  Shepard,  Canyon);  (1979;  in  de  to  such be  near-bottom Shepard  and  Marshall  and  Shepard,  Marshall,  la  and  Plata  and A b r a , t h e  velocity  t o d e c r e a s e away f r o m t h e bed w i t h m e t e r s a t  Abra was  distances  190  a b o v e b o t t o m o f 2 and maximum the  4 m,  observed v e l o c i t i e s  f o u r c a n y o n s . The  was  in full  made d u r i n g followed  3  and  ranged  f l o o d , and  a 24 h p e r i o d o f heavy  The  f l o w . The  The  s"' i n canyons  R i o de  la  t h e A b r a Canyon m e a s u r e m e n t s were  t h e r a i n y s e a s o n . The  period.  respectively.  f r o m 50 t o o v e r 70 cm  s t r o n g up-canyon  event  in  Rio  s w e l l , a n d was  a s e r i e s o f 7 p u l s e s o f 50-70 cm 12 h  30 m,  e v e n t s i n A b r a and R i o de l a P l a t a  were p r e c e d e d by u n u s u a l l y Plata  and  s~  maximum  1  Balsas  Canyon  c h a r a c t e r i z e d by  amplitude  R i o B a l s a s , A b r a and R i o de  over  la Plata  a  canyons  a r e a l l n e a r t h e mouths o f s e d i m e n t - l a d e n r i v e r s . G e n n e s s e a u x a t al  (1971) o b s e r v e d s u r g e s a t 1.5  Canyon 0.5-3  while  the  h w i t h peak  superimposed Johnson meter inlet  Var  (1974) 1-1.5  R i v e r was  amplitudes  on  ranging  from  above  bottom  40  currents.  i n Rupert I n l e t s  _ 1  Finally,  ,  to  100 cm  10-20  and E w i n g ,  1952,  and  cm  a  may  of submarine  1955; H e e z e n , 1963;  Shepard  estimated  for  subsequent  to  t h e 1929 G r a n d  earthquake  (Heezen  (Grover  and Howard, 1938;  the Walensee, continuous-flow  Switzerland density  were  1  Banks  1952).  U n d e r f l o w s of s e d i m e n t - l a d e n r i v e r Switzerland  m s"  et a l ,  to  i n Lake Geneva,  27.5  been  currents  up  and E w i n g ,  .  cables  Velocities  event  - 1  _ 1  current  1968; K r a u s e e t a l , 1 9 7 0 ) . the  s s  have  f o l l o w i n g e a r t h q u a k e s has been a t t r i b u t e d t o t u r b i d i t y (Heezen  Var  w i t h maximum down-  some o f w h i c h  the breakage  the  episodes l a s t e d  s e v e r a l e v e n t s r e g i s t e r e d by  s p e e d s o f up t o 120 cm  turbidity  i n f l o o d . The  in  a c o n t i n u o u s down-canyon f l o w o f  reported  m  m from the bottom  (Forel,  Bell,  w a t e r h a v e been o b s e r v e d 1885),  1942; G o u l d ,  (Lambert currents,  et the  al,  Lake 1951  Mead, and  1976).  speeds  of  1960)  U.S. and  These  are  which  are  191  correlated with river such  flows  the  d i s c h a r g e (e.g. Lambert e t a l ,  excess  temperature d i f f e r e n c e s  density  may  (e.g. Gould,  be  water  may  significantly  Jonkers,  s i n c e t h e buoyancy o f t h e  affect  m i x i n g a t t h e upper  i n t e r f a c e , and i s c e r t a i n  t o become i m p o r t a n t on s h a l l o w  at  i s deposited.  depth  turbidity lake  as  sediment  t h e advected water w i l l  d e p t h a n d may p a r t l y d e t e r m i n e surge  ( P h a r o and Carmack, Measurements  of  of mine t a i l i n g  Dickson  (1976b)  (1972; a l s o  in  were  (average)  4-328 h and  intermittent  slump-generated  stably  be p o s i t i v e l y  with  of the  i n the  have been made by Normark  and  S u p e r i o r , a n d by C a r s t e n s a n d T e s a k e r  with of  The  former  a c u r r e n t m e t e r moored 5 m a b o v e  5  and  velocities  0.5-30.6 cm s"  3 months. ranging  (peak)  1  increases  buoyant a t  currents  1975) i n R a n a f j o r d , Norway.  made  stratified  the eventual d i s s i p a t i o n  outfalls  o v e r two p e r i o d s  lasting  a  slopes  1978).  Lake  i n Tesaker,  measurements  a  continuous-flow turbidity  vicinity  bottom  In  surge f l o w i n g downslope through  or ocean,  In  p a r t l y d e t e r m i n e d by  1951; H o u b o l t and  1968). T h i s i s n o t a f i n e d i s t i n c t i o n , advected  1976).  Downslope  from  were  flows  0.3-13 cm s "  attributed  1  to  i n t h e t h i c k n e s s of t h e c o n t i n u o u s flow  g e n e r a t e d by t h e d i s c h a r g e . C a r s t e n s and Tesaker  (1972)  o b t a i n e d v e l o c i t y and  s o l i d s c o n c e n t r a t i o n p r o f i l e s w i t h i n a canyon sediments  by  a  tailing  c o n c e n t r a t i o n s averaged bed  were  27 cm s "  1  temperature p r o f i l e s The  on  discharge  130 mg l i t r e " , 1  a  bottom  eroded  plume.  i n pre-mine Near-bottom  a n d peak s p e e d s  slope  suspended  near t h e  o f 11°. S a l i n i t y a n d  were n o t r e p o r t e d .  a b o v e m e a s u r e m e n t s s u g g e s t t h a t by j u d i c i o u s c h o i c e . o f  1 92  the l o c a t i o n and time of f i e l d or  man-made t u r b i d i t y  operations,  naturally  c u r r e n t s may be o b s e r v e d  without awaiting  s e i s m i c d i s t u r b a n c e s . They a l s o g i v e e s t i m a t e s o f scales  t o be e x p e c t e d  i n a variety  the velocity  of c i r c u m s t a n c e s . Except f o r  t h o s e by C a r s t e n s a n d T e s a k e r  (1972),  one  mentioned  o r more o f t h e p a r a m e t e r s  occurring  however,  measurements  of  a t the beginning of t h i s  c h a p t e r were n o t o b t a i n e d . Acoustic  sounding  records of channelized t u r b i d i t y  both c o n t i n u o u s and s u r g e - t y p e , (frontispiece, i s devoted results  have  t o a d i s c u s s i o n of these incomplete  i n t h e sense  processes.  The  results  complimented  by t h e e x p e r i m e n t s  dumping o f d r e d g e  spoils.  7.1  Plume  7.1.1.  Meandering  2 0 0 kHz a c o u s t i c  A  approximately The  5°X10°.  edge  of  records.  The  f o r monitoring  of Bokuniewicz  surge  these  flows a r e  et a l  (1978),  surges generated  who  by t h e  Regime sounding  record  of  a  crossing  midway a l o n g t h e u p p e r r e a c h i s shown i n F i g . 8 1 .  r e c o r d was t a k e n  recorder of  Channel  chapter  d e s c r i b e d above, b u t  f o r channelized  o b t a i n e d sonographs of annular t u r b i d i t y  presented  of t h i s  and s i m i l a r  exemplify t h e value of a c o u s t i c sounding  The D i s c h a r g e  been  1 3 a n d 1 4 ) . The r e m a i n d e r  Figs.  are also  already  flows,  from  t h e CSS V e c t o r w i t h a R o s s  Model  200  o p e r a t i n g a t a p u l s e l e n g t h o f 0 . 1 ms a n d a b e a m - w i d t h The b o t t o m i s o u t l i n e d by t h e d a r k the light  g r e y band, which  Line' amplifier. This feature above a t h r e s h o l d s e t t i n g  causes  l i n e a t t h e upper  i s generated signals  with  by t h e ' F i n e amplitudes  t o be p a i n t e d a u n i f o r m s h a d e o f g r e y .  193  LINE 78  West H  East  110 m  H  - 40  50  - 6 0 (fm) Fig. 8 1 . S o n o g r a p h of t h e c h a n n e l a n d d i s c h a r g e p l u m e , l o o k i n g u p s t r e a m , d u r i n g f l o o d t i d e 3.5 h a f t e r l o w w a t e r , 22 November 1976, 1050 h PST. S = s i d e e c h o , P=plume. V e r t i c a l l i n e s indicate t i m e s o f p o s i t i o n f i x e s , t a k e n a t 1 m i n i n t e r v a l s . S e e F i g . 83 for l i n e l o c a t i o n .  The  channel  looking  upstream,  left.  Large  appears that  i s with  amplitude  throughout  the displayed  from  levees  the  as  i s  the  higher  scatterers section  i f  (fish?)  o f the water  apparent  beneath  the channel  itself.  on  side-echo i s the backscattered signal  the  which  i s spilling  h i g h e r west  channel right  i s  tilted  The upper  upward  across  profile  the  tendency  same  i s  from  on t h e p a r t  over  typical.  section  the right  e d g e of t h e  of  on  the  column.  Side-echo  channel a x i s , and  from beyond  superimposed the discharge the c r e s t of  cloud  t o west,  within  o r from  left  the to  sense. F i g . 82 the  of t h e plume levee.  east  were  distributed  Above and  out of t h e channel  i n the downstream-looking This  spill  levee.  levee are  the  upwards  plume,  the observer  west  extends this  into  i t would  to  shows  other  reach. A l l exhibit hug  the  right  profiles t h e same bank  and  1 94  LINE 24 1530 h  -180 m-  "  •i  w  -40  J  18 November  -50  LINE 4 8  (fm)  -40  2000 h 19 November " - 4 0 # ^ ^ ^ ? - 5 O  (fm)  LINE 54 1330 h 2 0 November  0920 h 2 4 November  F i g . _ 8 2 . F a c s i m i l e r e c o r d s s h o w i n g t h e plume i n t h e u p p e r r e a c h a t d i f f e r e n t t i m e s , November 1976. From t o p t o b o t t o m , t h e r u n s were made a t 1 h b e f o r e l o w w a t e r , 2 h a f t e r LW, 3.5 h a f t e r HW and a t LW. The F i n e L i n e a m p l i f i e r was s w i t c h e d o f f and t h e T r i s p o n d e r b e a c o n s were n o t i n p l a c e d u r i n g t h e b o t t o m r u n .  195  This due  suggests  that the higher  t o a net down-inlet  tidal  instead t o other dynamical (1974)  (western)  the  effects.  In  this  interface,  squared,  could  be  suggests  that  the  channel  context  axis i n this  which  up-inlet. higher  depends  This  right  is  tidal  and  important  overspill  l e v e e on t h e o t h e r , a s s u g g e s t e d channels.  Furthermore,  cross-stream balance  pressure  the  and  because  due t o p o s i t i v e  i t  of  which  on  feedback the  one  d e p o s i t i o n on t h e r i g h t  by M e n a r d  slope  gradient  speed  l e v e e and l e f t - h o o k i n g of t h e  reach are probably  preferential  stress  on t h e c u r r e n t  between t h e C o r i o l i s and c e n t r i f u g a l a c c e l e r a t i o n s hand  Johnson's  currents are up-inlet  s i n c e i t means t h a t t h e n e t r e s i d u a l  upper  levee i s not  s t r e s s on t h e d i s c h a r g e p l u m e , b u t  o b s e r v a t i o n t h a t t h e maximum t i d a l  is c r i t i c a l , at  right  (1955)  for  the i n t e r f a c e may  be  deep-sea implies a  sufficient  to  these a c c e l e r a t i o n s (see Chapter 8 ) .  Outfall  Fig. 83. L o c a t i o n s of t r a n s e c t s c o r r e s p o n d i n g t o t h e sonographs shown i n F i g . 81 ( l i n e 78) a n d F i g . 82 ( l i n e s 2 4 , 48 a n d 5 4 ) .  196 (a) H*-^  110 m  H  F i g . 84.(a) Facsimile records showing s p i l l i n g from the channel at increa o u t f a l l , 22 N o v e m b e r 1976. The times of bottom are 1050, 1100 a n d 1110 PST. (b) p r o f i l e s in F i g . 85 a n d i n t h e frontisp lines 67 a n d T T ' .  East  the plume sing distanc the p r o f i l e s P r o f i l e loca iece were o b t  within es from from top tions. ained al  and the to The ong  197  Fig.  84a  channelized outfall  downstream 67  over  the  LINE  a  series  plume a t  i n the  line  is  at  and  meander  which  the  plume  of  three  profiles  showing  successively increasing distances  upper  ( F i g . 85). levee  of  reaches.  was  These p r o f i l e s the  outer  bank  The  detected a l l show (Fig.  the  from  point  the  furthest  i n November  1976  the  spilling  plume  was  84b).  67  Fig. 85. P r o f i l e l o o k i n g d o w n - c h a n n e l a t l i n e 67 ( F i g . 8 4 b ) at 2 1 2 4 P S T on 21 N o v e m b e r 1 9 7 6 , s h o w i n g s u s p e n d e d m a t e r i a l a g a i n s t the r i g h t bank. Finally, the  upper  F i g . 86  reach,  material  spilling  1.  plume  The  bend, the  and  may  m above  a  hydraulic  between  over  be  the  upper  suggested  the  effects both.  of  by  the  centrifugal  the  by  reaches  at  the  1°  profiles  i n the  upper  southern  levee  The  the  the  axial  w i t h i n the  the  entering  lower  occur  plume  evident  echo above  initiated  might  the  side-echo.  before  and  consecutive  c r e s t of  clearly  masked  jump  two  showing the  i s not  i t s depth  has  or  each  material causing  10  shows  levee bend.  mouths of  a c c e l e r a t i o n of  This  may  as  flow  and bend  at  the that  some  5-  indicate  in axial Komar  submarine the  at  suggest  c r e s t rose  decrease  ( F i g . 25),  reach  channel  profiles  of  slope (1971)  canyons, i n the  or  bend,  •160 m-  N •' V.t •  j&Wj - 4 5  LiNE 59 -55  (fm)  b  F i g . 8 6 . ( a ) P r o f i l e s p a r a l l e l i n g t h e u p p e r r e a c h a x i s a t 1935 ( L i n e on N o v e m b e r 2 1 , 1976. ( b ) P r o f i l e l o c a t i o n s .  5 8 ) and 1944 ( L i n e  5 9 ) PST  03  199  7.1.2  A p r o n Regime Temperature, s a l i n i t y  the  plume  facsimile samples  are  between  (Fig.  73)  increased that  the  88.  The  plume, the  deepest  technique  backscatter  the  discharge  t e m p e r a t u r e and is  being  is  correlation  increased acoustic is  of  corresponding  clear  suspended s o l i d s which  in  the  sampling  (Appendix 6 ) . There i s a  i n d i c a t e t h a t warm f r e s h w a t e r  d e p t h , and  and  i n F i g s . 87 and  n e a r - b o t t o m zone of  Note  profiles  78/2  m f r o m t h e b o t t o m . The  elsewhere  t h a t of  suspended, p a r t i c u l a t e p r o f i l e s  are presented  1.5-2  the  plume.  station  records  described  and  at  and  salinity  advected  b e i n g m i x e d w i t h t h e c o l d e r , more s a l i n e (and  to  denser)  water above. 7.1.3  Rechannelized The  and are  Regime  acoustic records  14)  are  from the  shown i n F i g . 89  Fig.  14  with  rechannelized  UBC  which i n d i c a t e t h a t the  deployed along lights,  launch  using  the c h a n n e l  by  surface.  The  indicated  l i n e s were run  increased all  shore  three p r o f i l e s .  does not  are present The  constant.  this  l o c a t i o n s of t h e  decrease  r e f l e c t a decreasing  t h e g a i n was  while  i n the order  backscatter  were  surface  marker,  run  floats  a l l  with  s i n c e , i n order  to  the d i e l - m i g r a t i n g s c a t t e r i n g l a y e r , the  t r a n s e c t s were made a t n i g h t *  The  a  lines  tethered  f o r n a v i g a t i o n . L i g h t s were n e c e s s a r y contamination  13  f e a t u r e marked X i n  These  single-line  a x i s and  9,  regime. A d d i t i o n a l p r o f i l e s  i s a s s o c i a t e d w i t h the c h a n n e l .  the  avoid  of t h e p l u m e i n C h a p t e r 3 ( F i g s .  2,  3  and  layer lines  near  the  i s approximate. Zones  of  above or beyond the c h a n n e l  in  in signal  concentration  then  was  1.  intensity of  with  scatterers  depth since  32 1  \ \ /  TEMP CO S (%o)  i.i TEMP (°C> S (%•> -* I R U P 21  RUP 2A  14 Sopf.  13 Sept. 1978  TSP (ma/I)  31.7  TSP (mg/1) I U TEMP (°C) S <%o)  318  ;o70  32.1  i.a TEMP (°C) S (%.) ——A—  11.0  3M 1  31.7  .eV.''  RUP  2L  M Sept. TS7S  \  R U P 2B  »J Sept. 197S .•*  1  \  V  TSP (mg/1)  F i g . 87. T e m p e r a t u r e , s a l i n i t y and t o t a l s u s p e n d e d d u r i n g t h e a p r o n r e g i m e a t 7 8 / 2 , S e p t e m b e r 1978.  TSP (mg/l)  particulate  ( T S P ) p r o f i I e s ' f r o m t h e plume  to o o  201  Fig. 88. Sonographs corresponding t o p r o f i l e s i n F i g . 87, S h o w i n g t h e n e a r - b o t t o m t u r b i d zone and the sampling bottles descending into and r e m a i n i n g s u s p e n d e d w i t h i n i t . The b o t t o m e c h o (B) and a f a l s e e c h o ( F ) a r i s i n g from interference with another sounder are i n d i c a t e d .  F i g . ^ 8 9 . ( a ) , ( b ) and ( c ) P r o f i l e s t a k e n i n S e p t e m b e r 1979 d u r i n g t h e r e c h a n n e l i z e d the cloud r i s i n g o u t o f t h e c h a n n e l . D e p t h s i n m. ( d ) P r o f i l e l o c a t i o n s .  reqime.  Note M o  203  Assuming suspension,  that  the  profiles  from  the  low  axial  2  i n F i g . 14)  (X  bottom  either  slopes  in Line  be  caused  by  plume that  the  year  is  that  200  kHz  Fig. upper  a  the  The  level  the  is  on  the  probably  all,  the  the The  settles  less  channel the  (Line  of  fine  particles  of  that  of  in  at  Line above  features could and  suspension  T h i s would  or  that  these  in  away  1)  end  that  out  than  rises  western  extension  carrying  density.  be  taken  of  rising  and  course  September  the  require of  the  Regime  along  which bottom the  the  Fine  Line  event surge  was  diffuse at  away  from  c ) , there  channel.  at  The  from  1.5 107  an  by  first,  is  a  sharp The  returning  the  axis  of in  time.  first,  more  TT'  rather  the  phase  series  with  the  overspill  observed  a  from  detectable for  was  by  i s evident  side  of  indicated  after  south  the  time  soon  laterally  of  is a  channel  threshold  (frontispiece,  result  more  i s attenuated  overspill  spreads  which  transects  becomes echo  meandering  characterized  panel  the  the  frontispiece,  is initially  Channel  material third  an  detected during  event  above  event.  cloud  surge  interface,  spilled In  excess  Channel  echograms  of  be  i s suggested  tailing  d e p i c t e d i n the  amplitude  the  material  tailing  Surges  only  84b.  this  with  ( F i g . 87).  Meandering The  to  i t s  Turbidity  7.2.1  as  that  c l o u d at  to  water  stratification  previous  7.2  It  associated  escaping  3 ) . The  buoyant  channel  loses  3.  are  indicate  is believed  channel  the  zones  after  (Line  the  from  these  onset  of  and  the  with  gap  time.  in  the  southerly cloud  upstream  meander.  In  h. kHz  and  42.5  kHz  as  well,  204  although considerably less d i s t i n c t l y (Fig.  90).  These  frontispiece. transmitted the  from  large  turbidity 107 and  are  sound  reverberation  cannot  be  mechanism. amplitude  kHz.  so t h e r e l a t i v e  relative  scatterers  and  i n Chapter  a t 76/1  the  (Fig.  velocity  Because  interpretation  69)  was  records  the  shear  bathymetry  min  but  at  indicated  10 min  1  the  min  direction  speeds  differences t h e r e any  from kHz  the  the  than at  the with  evident  are  small,  was  t h e t i m e was  in  the  the  meters  are  during  the  the  correct  since there channel  nor  t h e same as t h e November  i n F i g . 69. The  samples i n these  time  a c t u a l sampling  interval  was  were so low t h a t a 10 min  interval  was  have  time the  two  during  i n c r e a s e i n t h e number o f r o t o r  time-series at  of  that  i s more d i f f i c u l t  i n t e r v a l s . The  needed f o r a measurable The  of  of the echoes  place  the  is  changes  i s n o t o b v i o u s , and  bathymetry  series are at 1  to  in  from  i s assurance n e i t h e r t h a t the mooring the  intensity  terms  intensity  (fish?)  to  3.  i n F i g . 70. V e r t i c a l  occurrence.  1976  in  respect  T h i s i s c o n s i s t e n t w i t h the R a y l e i g h s c a t t e r i n g  mooring  reproduced  that  with  interpreted  The  frequency  times than those i n the  normalized  pressure l e v e l ,  mechanism s u g g e s t e d  surge,  not  latter  c u r r e n t , h o w e v e r , a r e much h i g h e r a t 42.5  200  The  the  records are at l a t e r  They  backscatter  at  of 10  changes r e g i s t e r e d  been the  min  examined  event,  but  counts.  for  changes  in  no  significant  s e r i e s were f o u n d . N e i t h e r were  i n temperature  or  conductivity.  205  1352  1 3 5 6 PDT  F i g . 90. S o n o g r a p h s o f t h e 25 A u g u s t , 1976 t u r b i d i t y c u r r e n t at (a) 200 kHz (b) 107 kHz and ( c ) 42.5 kHz. A l l s o u n d e r s s e t a t 0.1 ms p u l s e l e n g t h and 5°xl0° be a m w i d t h . Note paper take-up problem with t h e 200 kHz r e c o r d e r ( A ) , and i n t e r f e r e n c e ( F ) among t h e s o u n d e r s . Compare w i t h f r o n t i s p i e c e a n d s e e F i g . 84b for t r a n s e c t l o c a t i o n .  206  7.2.2  Apron  Regime  Three  events  on S e p t e m b e r  12,  73).  The  107  The  42.5  kHz  The  were d e t e c t e d a t 2 3 4 4 h , 0225h a n d 0525h  13 and  15, r e s p e c t i v e l y a t s t a t i o n  78/2  (Fig.  kHz a n d 200  kHz e c h o g r a m s a r e shown i n F i g s .  91-93.  sounder  not  was  profiles  are  operational.  characterized  from the surge d u r i n g the passage bottom  echo  is  attenuated,  by i n t e n s e  reverberation  of which the a m p l i t u d e of  as  in  the  first  panel  a diffuse t a i l . and  time  scales,  surge passes the o b s e r v a t i o n  t h e echo  thicknesses surge  The  from the t a i l  and =  the  2-5  vertical  m)  that  growth  the  surge  was  s i m p l y grew w i t h  time,  driven  diffusion the  and  partly  point  in  f o r 1 t o 1.5 scales  from 4-6  h. T h e s e  (peak  surge  to those i n the August,  i n t h i c k n e s s of the t a i l  thicker  could  u p s l o p e , or t h a t the  partly  by t h e p o s i t i v e  1976  by  vertical  buoyancy  tail  turbulent  of t h e water i n  flow. A u n i v e r s a l shape  suggested  by  1966b; S i m p s o n ,  other 1969)  f o r t h e head workers  0  the present  of a d e n s i t y  (Keulegan,  s u r g e has  1957,1958; M i d d l e t o n ,  ( F i g . 94). Should t h i s  relation  the 10s).  (7.1)  Q  where u  hold  instance,  u = 1 . 5H / A t 0  been  on t h e b a s i s o f l a b o r a t o r y e x p e r i m e n t s , i n  w h i c h t h e r a t i o x/H = 1.5 in  length  are s i m i l a r  ( f r o n t i s p i e c e ) . The  imply  persists  the  of t h e  f r o n t i s p i e c e . F o l l o w i n g t h e s u r g e i s a l o w e r a m p l i t u d e echo  min,  PST,  i s t h e nose v e l o c i t y and  l e a d i n g edge o f t h e s u r g e and T h i s i m p l i e s nose v e l o c i t i e s  t i s the e l a p s e d t i m e between i t s c r e s t on t h e e c h o g r a m ( 5 r a n g i n g from  30  to  120-  cm  •I  s  F i g . 9 1 . S u r g e a t 2344 PST on 12 S e p t e m b e r 1978. ( a ) 200 kHz ( b ) 107 kHz. P u l s e l e n g t h s = 0 . 5 ms. B a c k s c a t t e r f r o m d i s c h a r g e p l u m e and l a r g e - a m p l i t u d e s c a t t e r e r s a r e a l s o e v i d e n t . S l a n t i n g l i n e s a t 200 kHz ( S ) a r e 60 Hz i n t e r f e r e n c e .  o  si  I  0230  Fig.  92. Surge a t  0 2 2 5 h PST o n  13 S e p t e m b e r  1978.  (a)  2 0 0 kHz ( b )  107 k H z .  Co  Fig.  93. Surge at  0 5 2 5 h PST on  15 S e p t e m b e r  1979. (a)  2 0 0 kHz ( b )  107 k H z .  ©  210  The  usual equation for t u r b i d i t y  surge flow  i s ( e . g . Komar,  1977) , u=  0.75[  0  where  g'Hj / 1  (7.2)  2  g' = ( A p / f> ) g .  This  0  8 x 10"  3  t o 50 x 1 0 "  3  g cm"  gives  schematic p r o f i l e  dashed  and body latter by  line  (or t a i l )  Ap  r a n g i n g from  surge: slug (solid a d a p t e d f r o m Komar,  line), 1977).  currents  (e.g.  generated  a r e a s s u m e d t o be  and t a i l  of  uniform  current  has  a  equation  similar  (7.2).  to that  This,  is  slugs,  The  followed  discontinuous  E x p e r i m e n t s by S h w a r t z e t a l ( 1 9 7 3 ) w i t h d e n s i t y  neck  density.  f e d by a c o n t i n u o u s s o u r c e , w h e r e a s a  turbidity  gave p r o f i l e s  Komar,  i n F i g . 94), i n which the e n t i r e head,  i s b a s e d upon l a b o r a t o r y e x p e r i m e n t s w i t h s u r g e s  a neck  and  o f t h e s u r g e i n F i g . 94 i s d i f f e r e n t  f r o m t h a t u s u a l l y assumed f o r t u r b i d i t y 1977;  of  for these events.  3  F i g . 94. Two t y p e s o f t u r b i d i t y c o n t i n u o u s source (dashed l i n e , The  values  slumpsource.  however,  i n F i g . 94, and a m o d i f i e d f o r m o f  discussed  further  i n the  following  chapter. The echo  of  suspended  September the  15 e v e n t  t h r e e , was  ( F i g . 93), which  the  weakest  observed while the c u r r e n t meters  f r o m t h e moored v e s s e l .  13 o c c u r r e d b e f o r e e i t h e r  gave  The  e v e n t s on S e p t e m b e r  the T r i s p o n d e r p o s i t i o n i n g  were  12  and  systems  or  21 1  the  current  records  meters  f o r September  h a d been d e p l o y e d . The a p p r o p r i a t e 15 have a l r e a d y  been  presented  current  in Figs.  74, 7 5 , 79 a n d 8 0 , on w h i c h t h e t i m e o f t h e e v e n t i n q u e s t i o n i s i n d i c a t e d . The d i r e c t i o n up-inlet  to  records  cross-inlet  flow  ( F i g . 79) i n d i c a t e a s h i f t which  i s most p r o n o u n c e d  near-bottom meter, and which l a g s t h e onset about (Fig.  4-6 m i n ( t w o - m i n u t e  There  meters i s no  records  the  obvious  i n up-inlet  i s also change  speed  surge  at  s a l i n i t y • or  by  records t h e two  g r e a t e s t a t t h e lowermost i n the  at the  meter.  temperature  (Fig. 74).  The There  which  the  s a m p l i n g i n t e r v a l ) . The s p e e d  79) i n d i c a t e a r e d u c t i o n  lower  of  from  pinger  record  i s a slight onset  at  during  t h e event  i s shown i n F i g . 9 5 .  decrease i n pinger-bottom  0525 h , w h i c h  distance  following  i s i n t e r p r e t e d a s a r e a l change i n  w a t e r d e p t h due t o s h i p m o t i o n , s i n c e  i t i s a l s o a p p a r e n t on t h e  e c h o g r a m ( F i g . 9 3 ) . No r e v e r b e r a t i o n f r o m t h e t u r b i d i t y  current  was o b t a i r i e d w i t h t h e 11 kHz p i n g e r . '—~~  ~-f-  0  5  2  ^  0 c  ^  ^  ^  ^  S  ^  f  ^  m  i  m  ^  0530  j 0530  B  :::; ' lWI2pa ,:;: i?  0540 PST  Fig. 95. Record from t h e 11 kHz p i n g e r , 15 S e p t e m b e r 1978. A= d i r e c t p u l s e , B= b o t t o m - r e f l e c t e d p u l s e , C= p u l s e s reflected by c u r r e n t m e t e r s a n d w e i g h t (W).  212  The with  change i n t h e d i r e c t i o n  a displacement  records  ( F i g . 79) i s c o n c u r r e n t  o f t h e s h i p 50 m t o t h e n o r t h  southward r e t u r n swing  ( F i g . 7 5 ) . The  southward  f l o w c o i n c i d e s w i t h t h e maximum  cross-inlet  peak  in  f o l l o w e d by a  displacement  ( e . g . when t h e s h i p i s s t a t i o n a r y ) .  that  equally  other  induce  rapid  records  shift  with distance  vertical  from t h e bottom  shear p r i o r  If surge,  the  t o the s h i f t  direction  This, the  A  voltage  the ship d i d not  in  these  and  passage of t h e September the  started after processing  was  due  t o t h e passage of t h e  of the s i g n a l  13 e v e n t  of the nose.  recorded  i s presented  vertical  during the  i n F i g . 96.  This  f o r w h i c h any p a r t of t h e head  and  even  then  the  recorder  was  t h e p a s s a g e o f t h e n o s e . The r e c o r d i n g and d i g i t a l  techniques  F i g . 97  through the course The  plot  on t a p e ,  h a v e been d e s c r i b e d  case the tape-recording volts.  of t h e  ( F i g . 79) a l l s u g g e s t t h a t t h e  o n l y event of t h e t h r e e  r e g i o n was r e c o r d e d  the  ( F i g . 79) a n d t h e a b s e n c e o f  of t h e meters from t h e path  contour  fact  ship-induced. change  separations  to  northward  t h e n t h e 4-6 m i n l a g c o u l d be due t o t h e f i n i t e '  lateral  contour  shift  (Appendix 7 ) , t h e decrease i n t h e amplitude  d i r e c t i o n c h a n g e was n o t  was  of  such pronounced changes i n d i r e c t i o n  other  and  displacements  the  is  output of t h e r e c e i v e r  saturated  a t i m e - s e r i e s of the r e v e r b e r a t i o n  at  6  records  of the event.  same  general  plot  as  features  are  i n t h e echogram  r e g i o n and s i m u l t a n e o u s echo a r e e v i d e n t .  i n C h a p t e r 3. I n t h i s  increase  present  in  the  voltage  ( F i g . 9 3 ) . The s h r i n k i n g body  i n the amplitude  of the  bottom  CO CO  f 0.00  1  1 2.94  1  1 5.88  1  1  1  TIME  I 11.75  8.81  I  I 14.69  I  1 17.62  (min)  F i g . 96. C o n t o u r p l o t o f d i g i t a l l y - p r o c e s s e d 200 kHz r e v e r b e r a t i o n f r o m t h e s u r g e a t 0 2 2 5 h PST on 13 S e p t e m b e r 1978. ( A l s o s e e F i g . 9 2 ) . E a c h p o i n t i n t h e c o n t o u r g r i d i s t h e a v e r a g e o f 10 s a m p l e s v e r t i c a l l y (0.2 ms) and o f 10 c o n s e c u t i v e t r a n s m i s s i o n s ( 5 s ) h o r i z o n t a l l y . N o t e t h a t t h e 1.0-2.0 v o l t i n t e r v a l i s c r o s s - h a t c h e d n o r m a l l y t o t h e c r o s s - h a t c h i n g i n t h e 0.5-1.0 v o l t i n t e r v a l .  200 kHz: NAV = 0  r  13 September, 1978  x i-  ~l  i  0.0  1  1  4.0  2.0  6.0  AMPLITUDE S C A L E (volts)  0.S m s 146.34  0. LU Q hZ UJ _l  I  D O  LU  160.0  0.0  0.66  1.33  200 kHz: NAV = 0  2.0  I  13 September, 1978  0.0  I  3.33  I  I  2.0  I  4.0  I  4.0  S.33  6.0  i  1 15.99  I  AMPLITUDE SCALE (volts)  6.0  X IQ. LU Q IZ  3  o LU  1 9.99  11.32  1  1 11.99  —i 12.65  r  T" 13.32  —i 13.99  r~  i 14.65  1  15.32  1  TIME (min.)  Fig. 97. Vertical p r o f i l e s of the signal backscattered l e n g t h = 0 . 5 m s . No a v e r a g i n g o f t h e s i g n a l . A z e r o v o l t of each p r o f i I e .  f r o m t h e s u r g e i n F i g s . 92 a n d 9 6 . P u l s e r e f e r e n c e i s p l o t t e d a t t h e b e g i n n i n g a n d end  215  The  record  concentration amplitude  s u g g e s t s t h e p o s s i b i l i t y t h a t an of  suspended  change d u r i n g that  the  during an  m a t e r i a l m i g h t be d e r i v e d  of t h e b o t t o m e c h o . The  method i s t h a t t h e a c o u s t i c  obvious d i f f i c u l t y  impedance of the  the passage of the e v e n t .  surge i s simply  interface  across  t h a t the  which there  of  the  from  the  w i t h such a  bottom i s l i k e l y  It  is  quite  r e a s o n f o r t h e a p p a r e n t a t t e n u a t i o n of  the  estimate  b o t t o m no  to  possible  the bottom echo  longer  exists  as  i s a marked change i n a c o u s t i c  impedance. Supposing that t h i s represent times,  the p r e s s u r e  t h e n p and  p'  i s not  the case,  amplitude  are  of  i n the  and  letting p  and  the bottom echo at  different  ratio  l o g ( p ' / p ) = 2 ( A - A') where  A  represents  (7.3) the  attenuation coefficient (Equation  3.3b).  From t h e ignored,  leaving  (<*,; E q u a t i o n boundary 200  kHz,  presumed  results  3.4)  layer  (3.4)  simplifies = 0.39 £  particle  that is  (7.3)  o f C h a p t e r 2,  thermal  the c o e f f i c i e n t  t o be  considered.  turbidites  the  i s v a l i d only  only  thickness  of  additional matter  i f the  bottom  constant.  (Equation  t h a t the p a r t i c l e  i n the  integral  t o t h e p r e s e n c e of s u s p e n d e d  t h e p a r a m e t e r b i n (3.4)  those  where  vertical  due  Note  reflection coefficient  radii  (Chapter  attenuation  for viscous  Noting  that  can  be  attenuation the  viscous  2.60b) i s a b o u t 0.0014 mm  i s >>1  as  l o n g as  it  i n the  surge are comparable  5 ) . In t h i s case the  may  at be to  expression  to  6 /a  (7.4)  i s the volume f r a c t i o n radius  p'  i n mm  and  occupied  by  where a s p e e d and  solids,  a  frequency  is of  the sound  216  of  1500  m s"  and  1  Making the the v e r t i c a l ,  200  kHz  f u r t h e r assumption that  From F i g . 97,  £'/a'  (H)  p and  excess d e n s i t y  8.8X10"  5 m has  are  been u s e d  proportional  of  1.7  that  a=a'=0.03 mm  given  by to  min  m s  just  gives  ( p* - p ) £ . a  a  of t h e  after  change  with  H<5  =4  This  the  in  nose  not  m, . t h i s  for this  value.  At  the  min,  corresponds  s u r g e on  corrected for side-echo,  Other A  acoustic  The  - 3  change  excess  in  density  the  and  t=4  in  Fig.  min,  and  t o the  of  96 the  square  or  0.14  root  to  g cm .  Using  - 3  a nose v e l o c i t y  agreement w i t h the v a l u e  same t i m e ,  o f nose s p e e d s b a s e d on  7.3  £'=5.2X10 .  signal  signal  the a s s u m p t i o n of a  shape f o r t h e h e a d . A s m a l l e r p a r t i c l e lower  4.3  ( F i g . 11), the e x c e s s d e n s i t y  t h a t a t t=4  i s in reasonable  estimated  _ 1  £r This  o  backscattered  t h e h e a d i s 16 t i m e s  1  and  3  t=0  m s" .  2.2  1  suspended s o l i d s c o n c e n t r a t i o n  (7.2)  to  cm" .  proportionality of  ( F i g . 92).  gives  From t h e c h a n g e i n mean b a c k s c a t t e r e d between  in  mm"  corresponds g  3  is  of  p'  = 0.17  assuming  therefore  a are constant  (7.5)  r e s p e c t i v e l y , which  Further  and  = 3.9€/a  where a f l o w t h i c k n e s s  £/a-  e  then  A = 2 ^ H  volts  have been a s s u m e d .  of  of  1.2  universal  r a d i u s would have g i v e n  however, the  a  s u r g e s h a p e s were  w h i c h w o u l d c a u s e an  underestimate  universal profile.  Events  number  of o t h e r  sounders  in  e v e n t s of September  interest 78,  and  were r e c o r d e d two  of  on  these  the are '  217  mentioned h e r e . The f i r s t increase  i s r e p r o d u c e d i n F i g . 98, which  shows  September  15  with  a  sudden  conductivity  2  h  before  t u r b i d i t y c u r r e n t , and p e r s i s t e d f o r s e v e r a l  hours. A simultaneous r e v e r s a l together  sudden  i n the c o n c e n t r a t i o n of suspended m a t e r i a l i n the near  bottom zone. T h i s i n c r e a s e o c c u r r e d a t 0330 h PST, the  a  drop  ( F i g . 74).  pronounced at the upper  to in The  up-inlet  flow  took  place,  temperature and i n c r e a s e i n latter  changes  were  most  meter.  0335 0338 PST Fig. 98. T i d a l l y i n d u c e d change i n the a c o u s t i c b a c k s c a t t e r at 200 kHz at 78/2 at 0330 h PST, September 15, 1978. Depths i n fm; 0=50, 20=60 fm. Another  event  ( F i g . 73)  d e t e c t e d at 78/1 shown  which  i n F i g . 99.  is  similar  in  some  respects  on September 16 at 0540 h PST, and i s  A c o u s t i c a l l y , the o c c u r r e n c e i s c h a r a c t e r i z e d  by a d i f f u s e c l o u d of s c a t t e r s , presumably p a r t i c l e s , m  from  the  bottom,  and  discrete  abates.  Similar  rising  rising  30  large-amplitude scatterers  ( f i s h ? ) which e i t h e r r i s e or move away from the cloud  was.  behaviour  of  bottom  a s . the  large-amplitude  218  scatterers this  i s observed a t the onset of the event  second  case  increase i n the echogram.  too,  the  onset  concentration  The  event  is  of  bottom meter lower  to u p - i n l e t abrupt  suspended  and h i g h e r s a l i n i t i e s .  at  shifts  followed  flow d i d not occur a t t h i s  reversal  in  material  on  to  the  higher  w h i c h a r e most a p p a r e n t a t t h e  ( F i g . 100), and which a r e  temperatures  In  i s f o l l o w e d by an a p p a r e n t  reflected  t e m p e r a t u r e s and l o w e r s a l i n i t i e s  i n F i g . 98.  by  trends  A sustained  time, but  there  a l l t h r e e m e t e r s , and a s h i f t  to  reversal was  an  t o southward  f l o w a t t h e l o w e r two, and n o r t h w a r d f l o w a t t h e upper meter. At the lowermost during  the  the d i r e c t i o n middle  meter,  there  is  r e v e r s a l which shifts  meter  is  an  initial  decrease  in  speed  i s f o l l o w e d by a g r a d u a l i n c r e a s e a s  southward.  The  particularly  direction  noisy  in  the  record  of  subsequent  the time  p e r i o d , w h i c h i s t o be e x p e c t e d g i v e n t h e s h e a r i n d i c a t e d by t h e upper  and l o w e r Fig.  mooring.  meters.  101 i s a p l o t  of  the  motion  the  ship  A t t h e t i m e i n q u e s t i o n t h e r e was a r a t h e r  t o t h e n o r t h , w h i c h i s t h e most l i k e l y shift  of  in direction These t i d a l  Fig.  68) may  shift  e x p l a n a t i o n of the abrupt  changes i n the l e v e l of a c o u s t i c zone, t o g e t h e r w i t h the  i n t h e c o n c e n t r a t i o n of suspended fine-scale  rapid  t o n e a r 0° r e g i s t e r e d a t a l l t h r e e m e t e r s .  from the near-bottom  the  at i t s  laminae  observed  i n d e e d be t i d a l l y  solids  backscattering  tidal  periodicity  ( F i g . 76), suggest  that  i n the sediment column (e.g.  induced.  Fig.  99. T i d a l l y  induced change  in a c o u s t i c  backscatter  at  78/1.  CD  c_>  MIDDLE  01  BOTTOM  o. o CL  "i  to  tii  i  r  r  ~i  1  ~~r  LD  1  ~r~  I I  o~1  1  1  "l  r  1  i—~i  1  1  1  1  T  1  r  ~i  ^ n 1  1  r  n  r*j "i  T  i  i—'—r  i  r  1  U l — L j  LD LU a 0540 PST  —i  15.87  Fig.  r  T  n  n  CL CL  1  1  1  1  16.12 1G.37 TIME(DAYS)  16.62  15.87  I I 16.12 16.37 TIME(DAYS)  I 16.62  1 0 0 . C u r r e n t m e t e r r e c o r d s a t 78/1 o n 15-16 S e p t e m b e r  15.87  1978.  I  r  1  16 12 16 37 TIME(DAYS)  1  1  16 S2  to to o  221  co  O •C\J  CD (X)  15.87  16.12  16.37  T I M E (DAYS)"  16.62  Fig. 1 0 1 . S h i p m o t i o n a t 78/1 on 15-16 S e p t e m b e r 1978. X a n d Y are east-west and n o r t h - s o u t h d i s p l a c e m e n t s of t h e s h i p .  222  CHAPTER 8 THE The of  SEDIMENT BUDGET AND d i s c u s s i o n now  CHANNELIZED TURBIDITY FLOW  t u r n s to the formation  t h e m e a n d e r i n g c h a n n e l . I n S e c t i o n 4.5,  submarine  channels  i n i t i a l l y develop  i t was  subsequent the  imposed  by t h e l o c a l  developments  will  slope  topography.  i n t h e p r o x i m a l zone  the mobile bottom,  determine At  upper  the  that  determined  and  lateral  This implies will  same  time  depend  that upon  i t i s clear  < sources  Furthermore, likely  to  of  i n the  r e p r e s e n t t h e most u n s t a b l e p a r t o f  because m a t e r i a l evolve  into  a  area  further  be  This  turbidites  downstream.  is in  displaced turbidity  restricted by  m i d d l e and  the  the  turbidity  currents.  slumping  current  to  most  of  Cu  lower reaches  most  is  more  significant  probable  t h e t o p end high  and  therefore  by  s l o p e s , the  supported  the  are  slump-generated  steeper a x i a l  reach.  developments  t h a t the l e v e e w a l l s  ( F i g . 2 1 ) , and  p r o p o r t i o n s on can  these  b o t h b e c a u s e o f t h e s t e e p l e v e e s l o p e s ( F i g . 26)  the r a p i d accumulation probable  and - t h a t  the e v o l u t i o n of the system  reach near the o u t f a l l  the system,  source  of t h e  content  upper  of  (e.g. F i g s .  59,  the 62  63). This suggests  channel  system  deposition by  suggested  i n t e r a c t i o n between t h e c o n t i n u o u s f l o w a s s o c i a t e d w i t h t h e  d i s c h a r g e and  and  maintenance  in a direction  by a c o m b i n a t i o n o f t h e s t e e p e s t a c c e s s i b l e constraints  and  that  upper  reach  f r o m t h e c o n t i n u o u s f l o w and  become  of  the  meandering  r e p r e s e n t s a s t a t e o f q u a s i - e q u i 1 i b r i u m between  b e d - l o a d t r a n s p o r t and  could  the  removal  levee slumping.  increasingly  These  of t h i s  material  latter  events  important i n d e t e r m i n i n g the  channel  223  morphology w i t h continuous  flow  overspill. number  This  and  (Section  To  i s supported  5.3,  Fig.  of  from  due  by  to  7.1.1, F i g .  outfall  deposition  turbidites  55),  the  and  in  possibly  the  the  that  by c o n t i n u o u s  the  equilibrium  a p p e a r s t o be  i n those  channel  number i s c o n s t a n t .  in  reduced  the  downstream of the  acoustic f i r s t bend  the upper  i n t e r a c t i v e a d j u s t m e n t o f t h e bed  turbidity  u  channel  84).  discharge  assumed  and  the  sediment column  s o l v e f o r t h e e q u i l i b r i u m m o r p h o l o g y of  continuous  as  the downstream i n c r e a s e  from w i t h i n the channel  a s d e t e r m i n e d by  is  dissipates  thickness  backscatter (Section  increasing distance  w i l l be This  and  the  rather d i f f i c u l t . Instead, i t  reaches of a submarine channel flow  reach  on  a  constant  t h a t f o r which the  assumption  is  formed  slope, bulk  discussed  the  Richardson in  Section  8.2.2.  8.1  Sediment Budget The  i s o p a c h maps i n F i g s . 17,  a planimeter time was that  of  arbitrarily  ( F i g . 102,  separated  source  to  the  d e p o s i t s , as  shown by  the  line  Assuming Section  a  dry  computed v a l u e s  T a b l e X I I ) . The  saddle XX'  point  i n these  b u l k d e n s i t y of  5.2.1),  and  tailing tailing by  c o n t r i b u t e d e q u a l l y t o t h e v o l u m e of  adjacent  computed  were i n t e g r a t e d  f r o m w a s t e dump m a t e r i a l  immediately  (see  21  t o o b t a i n the volume of d e p o s i t e d  each survey  each  18 and  compared  the to  mass the  of  1.3 the  total  are q u i t e s e n s i t i v e  between  at  by the  deposit assuming material the  two  figures.  g cm  - 3  f o r the  tailing  tailing  deposit  reported discharge.  t o the v a l u e  of  the dry  was The bulk  224  d e n s i t y a n d , t o a l e s s e r e x t e n t , t o t h e unknown s p e e d in  the  deposit  (1500 m s "  was a s s u m e d ) . S i n c e b o t h  1  v a r y w i t h d e p o s i t t h i c k n e s s due t o c o m p a c t i o n , constant  values  continuous  i s not  seismic  much l e s s t h a n  strictly  profiler  1.5 m t h i c k  material thickness for  valid.  of  a  sound  parameters  t h e assumption of Furthermore,  i s insensitive  because  (ringing) • i n the outgoing  of  to t a i l i n g deposits  decaying  p u l s e . An a t t e m p t  the  oscillation  to incorporate  i n t h e t o t a l v o l u m e was made by e x t r a p o l a t i n g  to  this zero  ( F i g . 1 0 2 ) . Good a g r e e m e n t e x i s t s b e t w e e n t h e v a l u e s  the t o t a l  t a i l i n g d e p o s i t e d and t h e t o t a l  tailing  discharged  (Table X I I ) .  3.0 -,  *  1974  o 1975 2.0 -i  •  1977  < UJ  cc <  1.0  15  10  THICKNESS  F i g . 102. A r e a c o v e r e d by d i f f e r e n t CSP s u r v e y s . The distal  tailing  deposit  zone s e p a r a t e d  (m)  tailing  was  of  divided  a  given  into  thickness for  a p r o x i m a l and a  by t h e l i n e YY' a t t h e l o w e r  end  of  the  225  meander deposit as  reach  (Figs.  17,  18  and  21)  was d e t e r m i n e d f o r t h e p r o x i m a l  described  above.  a n d t h e v o l u m e of t h e  z o n e i n t h e same  The e q u i v a l e n t mass a c c u m u l a t i o n  q u i t e c o n s i s t e n t f o r t h e two p e r i o d s w i t h a mean o f leaving  some 240 kg s ~  proximal is  zone  transported  remains  as  -surge-type Table X l l a .  to  1  the  turbidity  rate  144 kg  was s  _ 1  ,  o f m a t e r i a l t o be t r a n s p o r t e d o u t o f t h e  (Table X I I I ) . by  manner  A s s u m i n g t h a t most o f t h i s  channelized relative  turbidity  amounts  flow,  carried  the  material problem  by c o n t i n u o u s  and  currents.  Volume o f t a i l i n g  deposit  Date  f r o m CSP  Volume (10 m) 6  29 Nov. 74 21 O c t . 75 12 J a n . 77 Table X I I b . Average d i s c h a r g e CSP s u r v e y s . Interval (years)  3  12.58 1 5.64 1 9.82  rates during  Reported Rate (kg s - )  74- 75 75- 77  1  the i n t e r v a l s  Estimated (kg s " )  Rate  385 348  T a b l e X I 1 1 . O b s e r v e d mass a c c u m u l a t i o n rates zone d u r i n g t h e i n t e r v a l b e t w e e n CSP s u r v e y s  74- 75 75- 77  between  1  420 352  Interval (years)  surveys.  in  Accumulation Rate (kg s" ) 1  1 48 1 40  the  proximal  226  8.2 T w o - D i m e n s i o n a l T u r b i d i t y F l o w : It  is  currents and  assumed  that  Theory  the s o l i d - f l u i d mixture  in turbidity  c a n be a p p r o x i m a t e d by a f l u i d o f t h e same b u l k  appropriate  density  viscosity.  Such f l o w s  may t h e n  be  density  regarded  as  currents.  8.2.1 S u r g e F l o w For pp.  density  s u r g e s on a h o r i z o n t a l b o t t o m , B e n j a m i n  241-243) d e r i v e d  the  relation u  where u  of  gravity,  the  h e a d , g'= Apq/p  A^o t h e e x c e s s d e n s i t y  density  of  consistent  the with  and  value  ambient  the  fluid  1966b).  absence  denser  at the l e v e l layer.  Bernoulli's stagnation  results  of  constant  to  large distances  moving  with  wave. F r i c t i o n  the  0  (8.1)  obtain  B  the  (8.1)  is  (1957,  h a d an a v e r a g e up t o  is  2.3°  pressure  and  associated  a t t h e bed i s i g n o r e d .  In  the  i s taken  F i g . 103a) w i t h i n  obtained  I t i s the d i f f e r e n c e  fluids  nose.  the pressure 0  the  b o t h up-  the  ( &H ,  which d r i v e s t h e flow and which  between  f>  Keulegan  f o r slopes  p o i n t , and assuming t h e p r e s s u r e  and head r e g i o n .  pressures  and  ( F i g . 103a). E q u a t i o n  of t h e nose  Equation  theorem  sufficiently  the  0  , g t h e a c c e l e r a t i o n due t o  a  o f m i x i n g b e t w e e n t h e two f l u i d s ,  t o be c o n s t a n t  H  B e n j a m i n ' s d e r i v a t i o n was f o r a h o r i z o n t a l  bottom i n a frame of r e f e r e n c e  stress  constant,-  ( 1 9 6 6 b ) , who f o u n d t h a t C  o f 0.75 a n d was r e l a t i v e l y  nose  o  i n t h e lower l a y e r  experimental  Middleton  (Middleton,  the  (8.1)  2  0  0  thickness  1958)  = C g'H  2 c  i s t h e nose speed, C a d i m e n s i o n l e s s  0  (1968,  by  invoking  at . the  nose  t o be h y d r o s t a t i c a t down-stream i n these is  with  of  the  hydrostatic  balanced  by  the.breaking  the head  227  F i g . 103. S c h e m a t i c diagram of a density surge. (a) on a horizontal bottom, (b) on a s l o p i n g bottom. Except f o r the v e l o c i t y p r o f i l e a t x , f o r which the v e l o c i t i e s are r e l a t i v e to t h e b e d , v e l o c i t i e s and c o o r d i n a t e s a r e r e l a t i v e t o t h e n o s e . 3  Since H = 0  2H  in  the  flume  experiments,  Benjamin  (1968)  obtained C =  (1-25) / 1  o  S  where 103a).  is Flume  dimensional Section C= 0  the  0.77,  of nose h e i g h t  experiments  7.2.2),  indicated  a  universal  with  8  approximately  equal  to  which i s very c l o s e to the e x p e r i m e n t a l  Fig.  103b  can  and  f l o w , the  downdope.  gradient  due  s y s t e m . The  to  assuming n o n - l i n e a r , i n v i s c i d force the  pressure  integral  0.2,  non-  p gsin^s  i s balanced  0  surface  slope  i n the  d i f f e r e n c e b e t w e e n x, ~ Po  with respect  = to x  and  the  rotated c  pressure coordinate  (8.3a)  2  0  of  Referring  is  f u /2 0  giving  two-dimensional by  x  (see  value.  be e x t e n d e d t o a s l o p i n g b o t t o m .  P, from the  also  t o head t h i c k n e s s ( F i g .  shape f o r the p r o f i l e of a d e n s i t y c u r r e n t head  This theory to  ratio  (8.2)  2  the  equation  for  the  228  momentum " c o m p o n e n t p a r a l l e l between  the hydrostatic  t o t h e b e d . The p r e s s u r e  sections (x  difference  and x ) up- and down-stream  3  0  . of t h e nose i s P " Po assuming x„  that the flow  and x  at a sufficient  3  argument Unlike  speed  t o cases the  (8.3b)  Apghcos^S  =  3  differs  very  little  from  u  h e i g h t above t h e head. T h i s  where H  horizontal  0  i s much l e s s  case,  there  than  the  between  Q  limits the  water  depth.  i s now a p r e s s u r e  parallel  t o t h e bottom w i t h i n  t h e denser  absence  of f r i c t i o n  by t h e component o f g r a v i t y  parallel  t o t h e s l o p e on t h e e x c e s s  i s given  p -  p  A  If  t h e head  this  gradient  distance  m u s t be c o n t i n u o u s u  where C Shwartz  0  i s given  across  equation  (8.1)  which  geological 1977).  (8.4)  represented  flow  from  a steady  by  region. Since  (8.4)  3  h a s been  3  taken  a similar  where  result,  with saline  to x -x , 3  of slope  t o nose  H=H /2. Q  but without  slugs verified the and ( x  rather well  an e q u a t i o n  (e.g. Scheidegger,  by e q u a t i o n  ratio  (about  i  2)  height.  i s assumed  however, even M i d d l e t o n ' s  a  the pressure  x j sin/3  i s n o t a new r e s u l t ,  literature  at  and  z  was c l o s e t o t h e o b s e r v e d 2  source,  friction  z  i s independent  In fact,  (8.3c)  o  length, set equal  Although  and x  acting  3  u p t o s l o p e s o f 1 6 ° , w i t h C = 0.50  of  slug  head  experiments  1.6-1.7, w h i c h  0  the  + 2 ^ -  x )/H = 3  z  balanced  p.15) present  Their  of t h i s  be  i n the  (x - x )  t h e n o s e , p, = p  by (8.2)  e t a l (1973,  explanation. form  from  = • g'H.fc'cos^  2 0  = Apgsin^  will  which  density,  i s f o l l o w e d by c o n t i n u o u s  pressure  sufficient  3  layer,  gradient  in  of t h e form  most  of  the  1975 p. 2 1 8 ; Komar, (1966b)  results  (8.4), as indicated  are  inFig.  -  229  104,  although  Middleton's continuous quite  this  has  not  appeared  e x p e r i m e n t s were made w i t h  in  in  F i g . 104, i s s t r o n g e r  0  since  the ratio  (x^-Xj  h e a d f o l l o w e d by c o n t i n u o u s f l o w . T h i s dimensionless  distance  (8.4)., t h i s  i s not  )/H(, c o u l d be l a r g e r f o r a ratio  i s essentially  as i t i s i n  the  the  gradient  (8.3c)  continuous  flow.  F i g . 104 i t w o u l d a p p e a r t h a t t h i s d i s t a n c e  increasing  is  i n the r e s u l t s of  over which the pressure  i s n o t b a l a n c e d by f r i c t i o n , From  on s i n ^ , w h i c h  than  S h w a r t z e t a l (1973) f o r s a l i n e s l u g s . G i v e n unexpected,  literature.  s a l i n e h e a d s f o l l o w e d by  f l o w . The l i n e a r d e p e n d e n c e o f u  evident  the  decreases  with  discharge. 240 cm s J  —i  1  0.05  0.1  1  1.05  sin /5  F i g . 104. P l o t s o f 2 C versus bottom slope u s i n g Middleton's (1966b) r e s u l t s . T h o s e o f S h w a r t z e t a l ( 1 9 7 3 ) a r e shown by s o l i d l i n e s ( a : s a l i n e s l u g s ; b: t u r b i d i t y s l u g s ) . 1 / 2  0  230  I t h a s been assumed t h u s f a r t h a t t h e r e i s no m o t i o n head.  I n t h e e x p e r i m e n t s , h o w e v e r , i t was  shown t h a t  head.  circulation  ( F i g . 103) and w o u l d  the flow the  i n the absence  trailing  flow.  a r r e s t e d head mean  the denser  flow  layer  of a c o n s t a n t s u p p l y t o  In  a  set  on a h o r i z o n t a l  (Simpson,  sets  pronounced  m i x i n g o c c u r s i n t h e wake o f t h e in  This  1969,  of  flume  the  buoyant  of  1972;  lobe  f l u x of ambient  o f t h e mean f l o w Majisfield Middleton  and  a  dissipate head  Britter  and Simpson,  and  i n F i g . 103b  partly  cleft  (1968)  partly  to  is  12  similar  argued  that  in  a the  sketch Simpson,  to F i g . 9 i n the  pressure  gradients  driving  comparison  to the d i f f e r e n c e  i n hydrostatic pressure across  the  head  therefore  might  not s i g n i f i c a n t l y a f f e c t  the  form of (8.1) o r the  value  of  and  the c i r c u l a t i o n  the  s t r u c t u r e s d r i v e n by  and  an  t o the f o r m a t i o n of  i s b a s e d on F i g .  (1977),  (1966b). Benjamin  from  1978), i t  w a t e r o v e r r i d d e n by t h e n o s e . The  Milford  mean  experiments with  K e l v i n - H e l m h o l t z - l i k e b i l l o w s b e h i n d t h e h e a d and pattern  up  bottom moving a t t h e speed of  h a s been shown t h a t t h e m i x i n g i s due  complex  i n the  o b t a i n e d the e m p i r i c a l  i n t h e h e a d w o u l d be s m a l l i n  C . 0  300<Re<1100  (1966b)  where  Re  is  the  (8.5)  2 3  R e y n o l d s number. M i d d l e t o n  (1957,  1958)  noted a  slight  i n c r e a s e w i t h Re. A v a l u e o f Re of a b o u t channel-full  surges  in  ( 8 . 5 ) , C = 0 . 9 8 , y i e l d i n g a 30% o  from  however,  s u g g e s t e d t h a t t h e shape of t h e head might v a r y w i t h  and Keulegan  for  (1972),  relationship o"=0.61Re-°'  for  Simpson  either  ( 8 . 1 ) . Simpson's  Rupert  tendency 5x10  6  for  e  to  i s t o be e x p e c t e d  I n l e t , and u s i n g  increase  C  Re,  (8.2)  and  i n the v e l o c i t y estimate  e x p e r i m e n t s , however,  were  with  density  231  currents apply  f o r which H  was a b o u t h a l f t h e t o t a l d e p t h a n d may n o t  Q  t o t h e case of g r e a t  nonetheless of both C The  depth being  that c l a r i f i c a t i o n  considered.  o f t h e R e y n o l d s number d e p e n d e n c e  a n d t h e shape o f t h e h e a d i s n e e d e d .  0  i m p l i c a t i o n s of the i n t e r n a l c i r c u l a t i o n  sediment  t r a n s p o r t by t u r b i d i t y  particular driven  They i n d i c a t e  t h e upwards mean  partly  surges are reasonably  flow  by t h e v e r t i c a l  i n t h e head t o  behind  convection  the  c l e a r . In  nose,  which  of overridden  ambient  f l u i d a n d p a r t l y by e n t r a i n m e n t  i n t h e wake  determine  s i z e w h i c h c a n be t r a n s p o r t e d i n  the  suspension.  the  by c o n v e c t i o n  dilution  transformation  8.2.2  grain  t h e -head,  may  A l l e n (1971) h a s s u g g e s t e d t h a t t h e i n c o r p o r a t i o n o f  ambient f l u i d to  maximum  of  is  a t t h e base o f t h e nose  of t h e mixture  and should  of slumps i n t o t u r b i d i t y  contributes  be i m p o r t a n t  i n the  currents.  C o n t i n u o u s Flow For  motion  continuous are  parallel  density for a  0  equations  t o t h e bed a s i n t h e body o f t h e s u r g e s  in  F i g . 104.  integrating the l i n e a r i z e d  and J\-  equation  f o r t h e downslope  gives a  +*i=  ApgHsin/3  (8.6)  a r e t h e shear s t r e s s a t t h e bed and a t t h e upper  i n t e r f a c e . H i s t h e f l o w t h i c k n e s s a n d Ap t h e v e r t i c a l l y excess  of  the x-axis  ?  ?  the  with  component o f momentum  where  flow,  frame o f r e f e r e n c e  Vertically  written  current  density.  The  stresses  are  expressed  averaged  i n terms of drag  coefficients 7. +r = ( f . + f i ) p u /2 2  L  a  where u i s t h e v e r t i c a l l y - a v e r a g e d  = f f . u /2  (8.7)  2  downslope  speed.  The  drag  232  coefficient  f  is  0  equal  to  one  relative  roughness  of  b e d , and w h i c h c a n be o b t a i n e d f r o m a Moody d i a g r a m f o r  ( r a t i o of roughness  (Moody, 1944;  available  Harleman  d a t a , Bo P e d e r s o n  which  Darcy-Weisbach  factor  pipe flow  flow,  the  friction  the  f o r open c h a n n e l  fourth  depends  height to flow  drag,  a  transition position  other  from  thickness)  the  ( 1 9 8 0 , p. 38) has c o n c l u d e d t h a t coefficient  the  the  , 1 9 6 1 ) . I n an a n a l y s i s o f  d e p e n d s o n l y on t h e R e y n o l d s number. The on  on  hand,  undergoes  subcritical  to  of  flow  s h i f t s c l o s e r t o the bed. T h i s t r a n s i t i o n  occurs at  after  as  o f t h e maximum i n t h e n o n - d i m e n s i o n a l v e l o c i t y  L  bottom  sharp increase  supercritical  t-  the  profile  a  critical  v a l u e o f t h e b u l k R i c h a r d s o n number  which  is  usually  supercritical  close  Ri  = g'H/u  to  unity.  f l o w s have d i s t i n c t  Both  (8.7) a n d  the  i t i s clear  critical  steep  that depending  Assuming  1974  axial  Pedersen 0.2  slopes greater  a n d Komar,  and  1975  ( 1 9 8 0 , p. 94) 0.4  to  0.6-6°. The  transition  o f t h e R i c h a r d s o n number.  (8.9)  upon t h e v a l u e o f f ( = f + f ; ) , 0  be  for  in  r e a c h e d on a  deep-sea  t h a n 0.5°  canyons  f o r f=0.02.  discussions.)  sufficiently  The  and  supercritical  for  that  channels  (See a l s o Hand, analysis  indicates that Ri(crit)<1,  f o r f = 0 . 0 0 4 - 0 . 0 6 , and t h a t  transition  and  R i ( c r i t ) = 1 , Komar (1971) c o n c l u d e d  f l o w w o u l d be s u p e r c r i t i c a l with  velocity  = f/(2sin(3)  R i c h a r d s o n number w i l l  slope.  and  (8.8), Ri  so t h a t  the s u b c r i t i c a l  non-dimensional  d e n s i t y p r o f i l e s which are independent From ( 8 . 6 ) ,  (8.8)  2  this  by  Bo  b e i n g between range  in  f,  f l o w o c c u r s on s l o p e s g r e a t e r t h a n  p o i n t d e p e n d s on t h e  relative  roughness  233  of  t h e bed. Equation  momentum has of  (8.6)  fluid  is  incomplete  into the density current  been n e g l e c t e d .  When e n t r a i n m e n t  ( 8 . 9 ) becomes (Bo P e d e r s e n , Ri  =  because at  the  flux  i t s upper  o f low boundary  i s included, the equivalent  1980, p.92)  w,r  f +  u  (8.10)  2sin S j  where  w  e  is  the entrainment v e l o c i t y  d e p e n d s upon t h e s h a p e o f t h e v e l o c i t y i s subcritical  and F  i s a f a c t o r which  profile;  or s u p e r c r i t i c a l .  that  i s , whether  the  flow  and  w /u = 0.072sin 6 t h e second term i n t h e n u m e r a t o r i s u n i m p o r t a n t , and e  reduces t o (8.9).  For s u b c r i t i c a l  flow, (8.11) (8.10)  i  Rearranging  equation  (8.9) g i v e s  u = _2_ [ g'Hsin/3 ] f  (8.12)  2  which i s a Chezy-type The  question  equation.  arises  as t o the a p p l i c a b i l i t y  (8.1)  o r (8.3) and (8.11) t o t u r b i d i t y  only  one  modification  possible  effect  dynamics  of  theory and  that  the  by  these  particle  turbidity  Inman  would normally  settle  the  settling  gsinp on  parallel  the  fluid,  c u r r e n t s . There has  equations settling  might  have  on  (1963).  Very b r i e f l y , parallel  Bagnold  the  (1962)  the p a r t i c l e i s  to  the  bed, and  t o w a r d t h e b e d a t a r a t e W j c o s ^ where w i s s  velocity.  The g r a v i t a t i o n a l  acceleration  t o t h e b e d a n d a c t i n g on t h e p a r t i c l e and i n s t e a d y  t h a t done a g a i n s t  been  t o account f o r the  f l o w d e r i v e d by  a s s u m e d t o move w i t h t h e mean f l o w  particle  equations  flow. This modification i s the autosuspension  f o r continuous  modified  of  of  friction  flow  this  does  work  work must be b a l a n c e d  by  a t t h e bed and a t t h e upper i n t e r f a c e  234  and  to maintain  the p a r t i c l e  i n suspension.  The r e s u l t i s  + JI = ApgHt  sin,a -w /u  which i s a modified  form  (8.6)  and  implies  continuous  current  to exist  the  inequality  turbidity  ]  s  of  (8.13) that  for a  w < usin/3  (8.14)  s  must the  be  satisfied.  relation  Neither  (8.13)  have  Experiments with continuous been  conducted  negligibly (1976),  with  small  turbidity are  in  with on  and  0.03> mm  density  current  regard  clay  particles  Ashida  and  diameter of  profiles  within  a  with  Bo  to  (8.13),  i t  is  particles  (U=15 cm s  These  Pedersen's flow.  clear  that  i f w/u  theory  been  Pilkey  and P i l k e y  (1979),  specific,  perhaps  attempting  t o i m p r o v e upon  velocity chapter, by  in  but  momentum  (8.6) t h r o u g h  procedure  Middleton this  is  is The  ( 1 9 6 6 a ) a n d by Chu,  criticism  because of the d i f f i c u l t i e s  has  not  been  e n c o u n t e r e d when  ( 8 . 1 3 ) by i n c o r p o r a t i n g t h e  settling  equations.. In the remainder of t h i s  s u b c r i t i c a l continuous  equations  This  the  by  flow  universal  s m a l l t h e n t h e c o r r e c t i o n t e r m c a n be i g n o r e d . criticized  ;  profiles  sufficiently has  - 1  measurements  continuous  comprised of l a r g e p a r t i c l e s . agreement  continuous  quartz 1°.  with  Egashira  generated  f o r subcritical density current  With  c u r r e n t s have u s u a l l y  of  slopes  experimentally.  ) . T h e i r ' s a p p e a r t o be t h e o n l y  qualitative  profiles  suspensions  successfully  1  of v e l o c i t y  flow t u r b i d i t y  have  (w=0.08 cm s " ) _ 1  verified  velocities.  currents  u sin|3= 0.26 cm s  been  settling  however,  turbidity  t h i s c o n d i t i o n nor the v a l i d i t y of  turbidity  flow w i l l  (8.9), provided  supported  by  the  be d e s c r i b e d  (8;14) i s  results  of  satisfied. A s h i d a and  235  Egashira  8.3  (1975).  T u r b i d i t y F l o w and The  flow  r e s u l t s of the p r e v i o u s  in  the  determining type  meandering  the lower  channel,  with  now  be a p p l i e d t o  the  intention  c u r r e n t flow to the t r a n s p o r t  of  of  and  surge-  tailing  along  . Upper R e a c h : Mean F l o w  axial  to the c r o s s - c h a n n e l  slope  i n F i g . 25,  the  channel  between  lines  entrainment, section and  section w i l l  reach.  Referring  the  Channel.  the r e l a t i v e c o n t r i b u t i o n s of c o n t i n u o u s  turbidity  8.3.1  the Meandering  may  suggests  increase i n c r o s s - s e c t i o n a l area  of  and  2 i n d i c a t e s a h i g h r a t e of  t h a t the  in  flow i s s u p e r c r i t i c a l  this  at the  upper outfall  u n d e r g o a h y d r a u l i c jump.  intermediate  the  slope  section  of  sounding  runs  suggest  that  changes  there  inertial  the  t h e one  interfacial  relatively  to  in  decrease  relief  (Fig.  i n the n e i g h b o u r h o o d of l i n e  between the f l o w on  is  may  constant  t h e u p p e r r e a c h , and  c r o s s - s e c t i o n tends  cross-channel  channel  the  which together w i t h the steep slope  In c o n t r a s t ,  channel  i n F i g . 26 and  1  profiles  be  a  and  the 2  Both  the the  the a c o u s t i c -  5 (Figs.  cross-stream  ( C o r i o l i s and hand and  below l i n e  downstream. 26)  in  81  and  momentum  82)  balance  c e n t r i p e t a l ) a c c e l e r a t i o n s of  the pressure  gradient  due  to  the  s l o p e on t h e o t h e r . T h a t i s , f o r a l e f t w a r d - c u r v i n g  with u positive  i n the downstream  f*u + u / r 2  where f * i s t h e C o r i o l i s  direction,  = g'aH/W  parameter  (1.1x10'* s  (8.15) _  1  ),  r  is  the  236  channel radius of curvature the  ( 1 3 0 0 m) a n d AH/W  is  the  i n t e r f a c e ( a b o u t 0.11 a n d upward t o t h e r i g h t ;  and  8 2 ) . Komar  estimate  (1969) u s e d a s i m i l a r  turbidity  Monterey  Deep-Sea  current  velocities  Channel  by e s t i m a t i n g  from t h e c r o s s - c h a n n e l For the  a given  transverse in  excess d e n s i t y of the mixture  of  s e e F i g s . 81  force balance to meander  of  the i n t e r f a c i a l  d i f f e r e n c e i n levee  mass c o n c e n t r a t i o n  a  slope  the slope  heights.  M of t a i l i n g in a fluid  in  suspension,  of d e n s i t y  will  be Af> = ^p:-p ^ 0  where pj 6.1).  M  -  i s the grain density  Substitution  (8.16)  gives  concentration  of  the  (p.  various values values  for  Fig.  of u i n (8.15) and u s i n g  the  vertically-averaged 2  0  239).  The  (=uAM) a t l i n e  actual  Equation  at line  5 given  in  5)  Table  v e r t i c a l l y - a v e r a g e d s p e e d must be in  1  order  that  the  calculated  o f M be s i m i l a r t o t h e o b s e r v e d mean c o n c e n t r a t i o n s ( e . g . 1 1 ) , a n d t h a t t h e mass t r a n s p o r t Qd n o t e x c e e d t h e r a t e o f  tailing  discharge  For ranges  this  ( a b o u t 380 kg s " ' ) .  range of v e l o c i t i e s  values  the  Richardson  f r o m 0.095 t o 0.082 f o r H=10 m, and f r o m  f r o m 0.0073 t o 0.0063 f o r  p.  see  ( M ) , v o l u m e t r a n s p o r t Q ( = u A ; A=450 m  b e t w e e n a b o u t 0.4 a n d 0.8 m s " values  also  3  a  XlVa  (8.16)  ( 2 . 7 g cm' ;  s e d i m e n t mass t r a n s p o r t Q'  and  .  are  sin/?  consistent with  9 4 ) . A mean f l o w  =  0.038  subcritical  (Table flow  number (8.9),  f ranges  XlVa).  (Bo P e d e r s e n ,  s p e e d i n t h e r a n g e 0.4 t o . 0 . 8 m s  - 1  (8.8)  is  These 1980 also  reasonably  consistent with  the s i z e of m a t e r i a l c o n s t i t u t i n g the  bed  the  of  .from  movement  viewpoint  the  threshold velocity  ( e . g . M i l l e r , McCave a n d Komar, 1 9 7 7 ) .  for grain  Finally,  these  237  velocities 1.2xl0 .  correspond From  7  values for f  Bo  to  Reynolds'  Pedersen  r a n g i n g f r o m 0.004-0.002. The  t  (f ) i s therefore  roughness  of the  thickness, (Fig.  22)  of  suggests  the  that  and  of  2-3  f j are s i m i l a r than  (1971) f o r t u r b i d i t y  those  bed  flow in  in ratio and  submarine  these  t h a t the flow parameters  and  to  the  the flow  t o , but  o f 4 mm.  smaller  The by  a  0.009 a s s u m e d by Komar canyons.  Komar  (1969)  Deep-Sea C h a n n e l , w h i c h i s  and  the Rupert  friction  Inlet channel,  coefficients  roughness-heights  scale  the  suggests  similarly.  assumption  of c o n s t a n t R i i s based  on t h e o b s e r v a t i o n  s t e a d y , t w o - d i m e n s i o n a l d e n s i t y c u r r e n t s on an  constant  /jpH  relative  a t C o n s t a n t R i c h a r d s o n Number The  (Bo  a  t o the v a l u e o b t a i n e d h e r e . Because of the d i f f e r e n c e i n  g e n e r a l a g r e e m e n t among  that  material  of  coefficient  giving  roughness-height  o f 0.01  s c a l e between deep-sea systems  Flow  friction  0.004,  assumed f„=0.007 f o r f l o w i n M o n t e r e y closer  to  s  the s c a r r i n g of t h e l e v e e w a l l s  c o n t r i b u t e s an e f f e c t i v e 0  3.1x10  T h i s i s 50 t o 100 t i m e s g r e a t e r t h a n  grain-size  and  v a l u e s of t factor  about  0  0.0004.  of  (1980, p . 3 8 ) , a r e a s o n a b l e range  a t t h e bed  r a t i o of  numbers  slope tend r a p i d l y  Pedersen, parallel  the v e l o c i t y The below l i n e  1980  t o t h e bed  u, and  slope  p.  presumably,  the  assumption  of  t o a c o n s t a n t b u l k R i c h a r d s o n number  103)'. S i n c e t h e f l u x o f e x c e s s i s constant for flow  in  density  this  state,  t h e r e f o r e Ap H must a l s o be c o n s t a n t .  is  approximately  2 ( F i g . 25,  and  incline  i n s e t ) , as  constant  i n t h e upper  i s the channel depth  t h e r e f o r e , t h e f l o w t h i c k n e s s ( H ) . As that  Ri=constant  implies  that  Ap  reach  ( F i g . 26) a  result is  also  238  constant.  In the presence  of e n t r a i n m e n t  and  d e p o s i t i o n on t h e bed,  the  channel  observed  this  cross-section  (Fig.  26).  at the  Furthermore  downstream, it  c o n s i d e r i n g c o n s e r v a t i o n o f v o l u m e and  is  Q -Q 5  where  Q'  6  and  (Q )  (Q ), irrespective 5  t h a t under  of  by  these  less  the  than  solids  that  = (Q; Q^)/M  (8.17)  +  e  is  shown  must be  e  i n t h e s p i l l e d m a t e r i a l , and  which  readily  sediment  c o n d i t i o n s the volume r a t e of e n t r a i n m e n t  concentration  boundary  s t a t e c a n be m a i n t a i n e d o n l y i f  decreases  t h e volume r a t e of o v e r s p i l l  upper  a r e t h e mass r a t e s o f d e p o s i t i o n and  overspill,  respectively. F o r R i c o n s t a n t on a c o n s t a n t s l o p e , t h e d i s t a n c e i n a  t w o - d i m e n s i o n a l d e n s i t y c u r r e n t would  given  double  i t s thickness i s  by X =uH/w = H/(0.072 s i n ^ )  from e q u a t i o n middle,  and  (8.11). lower  The  doubling  reaches  r e s p e c t i v e l y . From F i g . 25, t h e constant slope section 0.25,  i n the upper,  indicates that  levee  entrainment.  (8.18)  lengths  are  3.6,  ratio  of  for 6.1,  the  lower reaches  in  and  length  flows thicker each  reach  t h a n 0.86, would  upper, 8.4  km,  of  the  0.21,  respectively.  i f t h e s e r e a c h e s were p e r f e c t l y  height  the  t o t h e d o u b l i n g l e n g t h i s 0.14,  m i d d l e and  uniform cross-section, the  which  straight 0.79  overspill  and  and This  and  of  0.75  of  because of  239  T a b l e X l V a . C o n t i n u o u s - f l o w p a r a m e t e r s i n t h e upper reach at line 5 (location g i v e n i n F i g . 2 7 ) . B o t t o m s l o p e = 2.2°, c r o s s s e c t i o n a l area=450 m . 2  u m s"  M* mg 1 "  1  0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0  m  1  80.2 1 55 254 376 521 690 882 1098 1337  s"  3  Ri**  kg s"  1  f/2 *** x1 0  1  90 1 35 180 225 270 315 360 405 450  3  7.2 21 46 85 141 217 318 445 602  0. 120 0. 1 03 0.095 0.090 0.087 0.084 0.082 0.081 0.080  4.60 3.96 3.64 3.45 3.32 3.23 3.16 3.11 3.07  * f r o m ( 8 . 1 5 ) a n d ( 8 . 16) ** H=10 m; f r o m ( 8 . 8 ) *** f r o m ( 8 . 9 )  T a b l e X I V b . T r a n s p o r t s by c o n t i n u o u s f l o w i n t h e upper reach between lines 2 and 5 ( l o c a t i o n i n F i g . 2 7 ) . C r o s s - s e c t i o n a l a r e a s a t l i n e s 2 a n d 5 a r e 700 a n d 450 m , r e s p e c t i v e l y . The Q and Q' a r e i n u n i t s o f m s " a n d kg s ~ , r e s p e c t i v e l y . 2  3  u m s"  1  0.4 0.5 0.6 0.7 0.8  280 350 420 490 560  * from ** Q =  180 225 270 315 360  1  Q*  Q**  29 36 43 50 57  1 29 161 1 93 225 257  Q' +Q* 71 1 32 219 338 494  46 85 141 217 318  25 47 78 121 176  (8.11) Q.+Qe-Qc,  s  8.3.2 E n t r a i n m e n t The  1  and S e d i m e n t T r a n s p o r t i n t h e Upper R e a c h  transports  determined  from  parameters  at  of  volume  (Q ) 0  and  mass {Ql) a t l i n e  (8.15) a r e g i v e n i n T a b l e X l V a . line  2  The  {Q• a n d Q') c a n be c a l c u l a t e d  5  equivalent using the  same v a l u e s o f u a n d M s i n c e R i i s assumed c o n s t a n t .  Similarly,  the  2 and 5 i s  volume  determined  rate  of  entrainment  ( Q ) between l i n e s e  f r o m e q u a t i o n ( 8 . 11 ) , t h e l i n e  s e p a r a t i o n (260 m) and  240  t h e mean c h a n n e l loss  rate  width at the i n t e r f a c e  (100 m).  Q^+Q'^can t h e n be o b t a i n e d f r o m  The  (8.17). Estimates of  the t r a n s p o r t s i n - a n d o u t o f t h e s e c t i o n between l i n e s are  presented  at l i n e  i n Table XlVb.  2 (CV) c a n n o t  Now  assume  overspill  rate  the rate  of  discharge,  and l i n e  1  the  and l i n e  rate  of  loss  by. d e p o s i t i o n  f o r which  deposition  This  the  d e p o s i t tended  _  1  close  loss  of  in  the  CV  t o u-0.6 m s ~  solids  and  by  increase  the  overspill  function  thickness of  of  bed  rates  channel  o f 31  time  ( F i g . 67  only  some  the net accumulation  _  1  solids  f o r the  - 3  on t h e l e v e e s a n d 2 kg s ~  22 kg s "  i n two z o n e s ,  1  upper  1  i scarried  1  discharge  reach,  e a c h 100 m w i d e a n d and l i n e  ( l a t e r a l l y ) beyond t h i s zone, rate  of  390 kg s " , 1  the entrainment  not bend.  rate, the s a l i n i t y  of  centered  5. I f a n o t h e r then  225 kg s "  t r a n s p o r t e d o u t o f t h i s s e c t i o n by s l u m p - g e n e r a t e d Given  on t h e  (=600x33/900) c a n a c c o u n t f o r  t h e l e v e e c r e s t s , between t h e o u t f a l l  22 k g s "  on t h e  t h e l a r g e d e p o s i t on t h e s o u t h s i d e o f t h e f i r s t  Accordingly  on  kg s  and  b e d i n t h e u p p e r r e a c h c a n be made  were o b t a i n e d i n t h e 900 m l e n g t h o f t h e  including  and  the t a i l i n g  f r o m F i g . 2 1 . A s s u m i n g a d r y b u l k d e n s i t y o f 1.3 g c m deposit,  (Table  1  .  t o be a l i n e a r  on  reach  and t h e  Appendix 6 ) , rough e s t i m a t e s of t h e r a t e s of a c c u m u l a t i o n levees  and  r a t e s between t h e  )/260,„ must b a l a n c e  occurs  the t o t a l  i s 180 kg s  Because  5. The s o l i d s l o s s  5, 600 (QJ +Q^  discharge.  5  t h e mean  i s c o n s t a n t a l o n g t h e 600 m s e c t i o n o f t h e u p p e r  of  XlVb),  and  0.8 m s ~ .  that  beween t h e o u t f a l l outfall  2  S i n c e t h e mass t r a n s p o r t o f s o l i d s  exceed  s p e e d must be l e s s t h a n  sediment  for a must  be  water  in  1  flow. the  241  t h e plume c a n be c a l c u l a t e d  t o determine the e f f e c t  w a t e r on t h e plume d e n s i t y . B e c a u s e vertically 1975), salinity  i n the i n l e t  Inlet  i s often  of t h i s argument t h e t e m p e r a t u r e and t h e  are set at their  annual  mean  9 °C .and 3 0 . 5 p p t . The d i s c h a r g e i s 10% s o l i d s , 50% s e a - w a t e r ' by v o l u m e ,  and  liquid  phase  The —0.54 m a  3  mean  s" ,  transport  of  speed  of  0 . 6 m s~  1  water  isothermal conditions the (Cox  et  at  the  water  i s Q^= 420 m  (Qj"0.54)/Q-=  which corresponds t o a sigma-t sea  water  a l , 1970). outfall 2  is at  s " . The s a l i n i t y o f  3  1  F i g . 87),  30.46 ppt  23.61,  of  while  albeit  of  with depth i n the  plume  the with  (Chapter  t h a t t h e s e o b s e r v a t i o n s were t a k e n d u r i n g  the u n c h a n n e l i z e d phase.  The v a l u e s o f s i g m a - t  e x c e s s d e n s i t y o f t h e plume i s d o m i n a t e d p r o v i d e d M > 47 mg  that  i s 2 3 . 6 4 . The v a l u e o f S i s c o n s i s t e n t  the observed drop i n s a l i n i t y 7,  40% f r e s h  of  i s g i v e n by S= 3 0 . 5  ambient  fresh  values  w h i l e t h e volume t r a n s p o r t o f water p a s t l i n e  1  t h i s water  and under  would have a s i g m a - t o f 13.06  volume  nearly  15-50 m ( s e e D r i n k w a t e r and Osborn,  homogeneous b e l o w  f o r the purpose  Rupert  of t h e f r e s h  by  indicate  that the  suspended  solids  1~ . 1  8 . 3 . 3 Lower R e a c h The  slope i n the lower reach i s 0 . 4 7 ° ,  f l o w t h i c k n e s s of 5 m and 200 m . 2  0.28  From Bo P e d e r s e n  a  maximum  with a channel-full  cross-sectional  (1980, F i g . 5 . 1 4 ) ,  area  of  R i s h o u l d be b e t w e e n  and 4.0 a t t h i s s l o p e f o r h i s s u g g e s t e d range of v a l u e s of  the drag c o e f f i c i e n t  f (0.004-0.06).  From  (8.12)  a n d an  a v e r a g e c o n c e n t r a t i o n o f 400 mg l " , u= 0 . 0 5 5 - 0 . 2 1 1  assumed  m s" , giving 1  242  4-17  kg  s"  f o r t h e mass t r a n s p o r t  1  Since  i t was  accumulated reach  tailing  must be  transported 225  kg s "  upper  estimated  about by  kg  by  The  mean r e c u r r e n c e a t 2-5  slug  other  of  are  a  currents  the  on  and  time f o r the  be  flow. out  The  of  the  turbidity  currents  has  deposits  in cores  from  slug-type  low  Assuming  ( F i g . 94),  slopes,  for  not  contribute records  the  that  and  the  that  the  motion  of  t h e mass t r a n s p o r t  FMu TA  of  (8.19)  0  time  h e a d and The  equation  previous  f r e q u e n c y of scale  tail  of  similar to  the  to the  chapter  occurrence  representing  the main p a r t of  significantly  i n the  been  by  T is a  position.  g o v e r n e d by ah  It  of  turbidite  surge i s given  probably  facsimile  this  currents accounts  ( S e c t i o n 5.3.3).  of  whole  to pass a given  15  transported  of  must  1  continuous  c h a n n e l c r o s s - s e c t i o n , F i s the  to  s"  o  the  of t u r b i d i t y  about  than  t o be  interval  Q'=  flow  223-236 kg  ( 8 . 1 ) , w i t h C =0.75, c h a r a c t e r i z e s the  as  s e d i m e n t by  length  then  1  d from the  surges  nose v e l o c i t y  A i s the  volume  well.  i n the m i d d l e r e a c h  turbidity  the  the  Frequency of T u r b i d i t y Surges  estimated levees  from  slump-generated t u r b i d i t y  the d i f f e r e n c e reasonably  The  s" ,  mechanisms  8.2  flow.  t o t a l mass t r a n s p o r t t h r o u g h  of m a t e r i a l e s t i m a t e d  1  reach  8.3.4  in Section  t h a t the 240  by c o n t i n u o u s  the  the  following  c u r r e n t , which i s  (8.9),  is  assumed  t r a n s p o r t . From  (Figs.  91-93),  the  T  is  (1962)  has  min. remains  to estimate  Ap i n t h e  head. Bagnold  suggested that at suspended sediment c o n c e n t r a t i o n s  greater  than  243  9%  by v o l u m e , g r a i n - g r a i n c o n t a c t  increase this  in v i s c o s i t y with  is  approximately  c a u s e s a much g r e a t e r  increased  the  same  concentration. concentration  a t t e n u a t i o n of sound i n suspensions  becomes  multiple-scattering  and  bulk  density  1.12  g cm  - 3  pronounced  of  (Chapter 1.18  inferred surge  g cm ,  (Figs.  as an u p p e r l i m i t  surges.  W i t h Q'  3.7  6  10'  therefore, interval  s~ , 1  recorded  96 and to  = 223-236 kg s' , 1  i s of the order  d e t e r m i n e d from the  non-linear  to  the  backscatter  concentration the  (8.19). of  at  that  which  the  due  to  value  of  from the  most  9 7 ) . F o l l o w i n g Komar ( 1 9 6 9 ) ,  the  from equation  Note  that i t corresponds to a  compared  -3  from the  i s taken  x  3),  r a t e of  in  turbidity  surge frequency  i s F=3.5-  The  recurrence  interval,  3.1-3.2 d a y s , w h i c h i s w i t h i n  cores.  9%  the  244  CHAPTER 9 SUMMARY AND A  time  reflection  series  of  surveys  a  three  through  year  three  ( c ) t h e r e c h a n n e l i z e d s t a t e . The  been u s e d t o c l a r i f y A primary  general,  and  continuous latter  c e r t a i n aspects  remote  turbidity  (b) t h e has  of t h i s  of  currents  flow a s s o c i a t e d with  been  scattered,  through  absorption  suspended  tailing  sediments  in  including  the  discharge.  i n t e r f a c e must be c o n s i d e r e d . the long-wavelength scattered  wave  relation expressing thermal  the  absorption.  These  a b s o r p t i o n can  mineral  origin,  which  these  ratio  evidence,  thermal  The  by  be  are  incident  and  a p p l i c a b l e to  obtained  processes,  magnitudes  for  together of  the  with  viscous  a  and  i s shown t o be c o n s i s t e n t w i t h  and  i s used t o demonstrate  neglected  simplifies  that  f o r most s o l i d p a r t i c l e s the  calculation  of  of the  losses considerably. theory  of  acoustic  remote  scatterers  i s presented.  at  t h e b a c k g r o u n d n o i s e o f an  which  which  at the w a t e r - p a r t i c l e  expressions  region  relative  This  e x i s t i n g experimental  additional  Explicit  (Rayleigh)  as m o d i f i e d  sound waves, b o t h processes  has  of a c o u s t i c  phenomena i n v o l v e h i g h s u s p e n d e d s e d i m e n t l o a d s , a t  the a d d i t i o n a l a t t e n u a t i o n of the  the  problem.  in particular,  the  tailing  subsequent phases  r e s e a r c h c o n c e r n s t h e use  detection  the  morphological  focus  i n f o r m a t i o n from the  p a r t of the  sounders f o r the  meandering channel,  seismic  show t h a t  successive  a p r o n and  and  and  period  (a)  regime,  initial  side-scan  regimes:  initial  the  bathymetric,  over  t a i l i n g deposit evolved  CONCLUSIONS  sensing  I t i s shown t h a t a t ideal  high  of  Rayleigh  frequencies,  transducer  i s due  to  245  thermal molecular motion choice  of  study  of  was  frequency the  i n the  water, there  for a given  f r e q u e n c y dependence of  An  consistent  empirical relation  solids  concentration  form w i t h R a y l e i g h signal with  level  the  The  sectional profile tape-recorded  does not  secondary  standards,  is  channelized  ( F i g . 13).  the  consistent  Furthermore, also  use  of  target  the  vertical  sizes responsible  Such  particularly  from  targets  in  the the  suspended p a r t i c l e s  e i t h e r i n the of  the  cross-  b a s e d on  s p h e r e s as p r i m a r y  recommended.  greater  of  in  consistent  plume  Such p r o f i l e s are  range  are  sheltered  for  or the  calibration useful  as  environments  p r o b a b i l i t y of p l a c i n g a t a r g e t  channel i s d i v i s i b l e  profiles. transverse  The  distinct  in plan  three and  upper r e a c h hooks to the  Coriolis  and  deep-sea  reaches,  on  the  left,  two),  channels.  which  b o t h a x i a l and  the  The  as  Menard  meanders of  geometrically  and  p r e s e n c e a p p e a r s t o d e p e n d upon t h e  due  (the  the  to  latter  (1955)  s i m i l a r t o meanders i n s u b a e r i a l axial  are  transverse  apparently  centrifugal accelerations  more i m p o r t a n t of for  into  reach are their  suspended  axis.  morphologically  suggested  the  over  not  the  ( F i g . 11).  size distribution  is  being  and  shown t o be  kHz,  90).  discharge  standards  The  Fig.  200  of  The  acoustic  (e.g. level  and  signal  i s used to e x t r a c t a  reverberation.  is  107  target  change shape s i g n i f i c a n t l y ,  there  backscattered  empirical relation  the  horizontal,  where  to a standard  optimal  quantitative  42.5,  between s i g n a l  s c a t t e r i n g theory  signal  assumption that  expectations  i s p r e s e n t e d and  relative  theory.  the  with  an  s c a t t e r e r r a n g e . No  conducted. Q u a l i t a t i v e comparisons at  however, are  exists  has  middle rivers,  slope  and  246  discharge,  as  entrainment  at  consequently channel  that these  to  the  coarser  t h e subaqueous c a s e ,  interface,  energy) be  losses  considered.  processes  induce  and u n d e r s t o o d  t o the channel  near-outfall  area  in  however,  material  (and  through d e p o s i t i o n and i s evidence  morphological  changes  to  which  (e.g. F i g . 4 2 ) .  axis  that the coarsest  and  There  sediment samples i n d i c a t e  restricted i s probable  In  upper  potential  Surficial  it  the  be r e c o g n i z e d  are  rivers.  o v e r s p i l l must  suggest can  with  that  (Figs.  coarse  deposits  44 a n d 5 0 ) . A l t h o u g h  sediments are  also  restricted  some " s p a t i a l l y a v e r a g e d  d e p o s i t s were f o u n d f u r t h e r  downstream  (Figs.  sense, 46  and  50). The  concentration  approximately  linearly  5 2 ) . The s u g g e s t i o n chalcopyrite  is  larger particles. coarsest of  clay  of  Cu  in  w i t h t h e amount  a of  deposit sand  i s that the f r o t h - f l o t a t i o n  increases  present ( F i g . process  by w h i c h  e x t r a c t e d from t h e g r i n d i s l e s s e f f i c i e n t f o r The c o n c e n t r a t i o n  sediments, and higher ( F i g . 53), probably  with the s o f t e r minerals  of i r o n  is  lowest  f o r the  i n deposits with larger fractions because of t h e a s s o c i a t i o n of i r o n  and, t h e r e f o r e , the f i n e r  particles.  T u r b i d i t e s c o n t a i n i n g t h e Ta, Te, and p o s s i b l y t h e Td  intervals  of  and  copper, and had s h a r p c o n t a c t s  of  which  exhibited  graded  in  both  to load-pockets  f l a m e s t r u c t u r e s . The u s e o f c o p p e r a n d i r o n a s  environment.  The  shows c o n s i d e r a b l e  frequency  texture  w i t h t h e u n d e r l y i n g mud, some  features similar  t r a c e r s of such d e p o s i t s of  and  t h e Bouma s e q u e n c e were f o u n d i n t h e s e d i m e n t  column. These d e p o s i t s were v e r t i c a l l y  casted  Tb  and l o a d chemical  promise i n t h i s  and t h i c k n e s s of these  type  deposits  247  relative  t o t h e i n t e r v e n i n g mud  from  the  This  latter  c h a n n e l a x i s , but i n c r e a s e d w i t h d i s t a n c e  existing  observation  literature  contradiction. axis  decreased with l a t e r a l  is  on  I t may  at  turbidites,  reflect  over  the  downstream.  variance  but  with  the  i s not n e c e s s a r i l y  a  the l a c k of c o r e s from the c h a n n e l  i n t h e p r e s e n t s t u d y , due  position  complete  distance  channel  to the d i f f i c u l t y and  in  in  penetrating  maintaining sand w i t h  our  changes  in  coring apparatus. Deposition tailing  rates  thickness  are  derived  established from  from  seismic  w a t e r d e p t h and t h e d o w n - c o r e v a r i a t i o n s  the  profiles,  changes  i n the c o n c e n t r a t i o n of  the f r u s t u l e s of l a r g e d i a t o m s . A c c u m u l a t i o n r a t e s r a n g i n g 0.3 infer  to  turbidites  per  unit  turbidity  surges  d i s t a n c e s from the o u t f a l l  t o 43-64 d. D u r i n g t h e s u b s e q u e n t virtually  absent  apron, i n d i c a t i n g turbidity  from  and  both  the  backscatter  i n t e r v a l s of although  this value  frequency  2at  increased  regime, t u r b i d i t e s  column  of  were  d o w n - i n l e t from the of  occurrence  of  the d i s t a n c e s t o which they propagate are  records  from  the  are  presented  discharge  c h a n n e l r e g i m e . They i l l u s t r a t e : forming  interface left  apron  number  i n t h e p r e s e n c e of a l e v e e d c h a n n e l .  Facsimile  levee  the  channel phase,  ( 8 . 3 km),  the sediment  that  surges  from  l e n g t h of c o r e . Recurrence  5 d were o b t a i n e d f o r the meandering  greater  from  s e v e r a l m e t e r s p e r y e a r were o b t a i n e d , and were u s e d t o  the f r e q u e n c y of  large  in  the  sloping  outer  plume  the  acoustic  during  the  meandering  ( a ) t h e plume s p i l l i n g  (concave)  upward t o t h e r i g h t  i n the downstream-looking  showing  bank  in  bends,  over  the  (b) an  i n a bend c u r v i n g t o t h e  s e n s e , and  (c) t h a t the d i s c h a r g e  248  plume e x t e n d e d a t l e a s t p a r t way loss due  of  s i g n a l at greater a x i a l  to i n c r e a s e d a t t e n u a t i o n over  deeper water. than  might  The be  s l o p e of the expected  a c r o s s the c h a n n e l .  the  d i s t a n c e s may the  longer  interface  from  meander  the  the c r o s s - s t r e a m  reach.  have been return  partly  interfacial  s t r e s s was  not  in  steeper  d i f f e r e n c e in levee  height  slope did  w i t h the phase of the t i d e ,  tidal  The  paths  i s considerably  In the upper r e a c h the  not change s i g n i f i c a n t l y that  along  indicating  significant  at  these  times. The  deep water c u r r e n t s i n t h i s  relationship  m i d - e b b t o m i d - f l o o d and  f l o o d t o mid-ebb, a l t h o u g h to  high  sufficiently rate  and  exhibit  water,  reversal  down-inlet  to u p - i n l e t  particularly  i f the  flow  of  descent  records c o n t a i n evidence  of the t i d a l  total  Without could  of  the  velocities profile  by  heads.  The  steepest  four  d u r i n g two  have  can  j e t through  of the passage of t u r b i d i t y  i s by no means o b v i o u s ,  sounders,  from  flood tide  column i n the Hankin P o i n t a r e a d u r i n g f l o o d t i d e .  A  unusual  of w h i c h  acoustic been of  surges  30-120 cm  i n v o k i n g the  s"  1  by  the  The  the water  current  surges.  The  however.  current it by were  universal  meters  is unlikely  the  current  estimated shape  highest estimate corresponded  l e a d i n g e d g e , most o f w h i c h was  second e s t i m a t e ot  occur  were d e t e c t e d w i t h t h e a c o u s t i c  records  identified  mid-  range i s  h i g h . T h i s p a t t e r n a p p e a r s t o be d e t e r m i n e d  depth  signature  an  t o the phase of the t i d e . Flow i s u s u a l l y u p - i n l e t  from a p p r o x i m a t e l y  close  inlet  for  were  in  place.  t h a t the  events  changes.  Nose  from  the  density  surge current  t o t h a t event  with  recorded  tape-.  1 7 0 c m s"' c o r r e s p o n d i n g  on  t o an e x c e s s  the A  density  249  of  0.12  g cm"  was  3  obtained  r e c o r d , and  by a s s u m i n g  suspension  did  l e n g t h of the  not  bottom  change  interval  model,  increases  f r o m 4-6  reflection  the  including  within  decreases u n t i l  The  first  6 min,  velocities, was  min  after  the  seismic  first  i t disappears.  the  or over a  by  (b)  that  the  flow  onset.  profiles  entrainment,  this  of  and  unaffected  cross-sectional  the  of  through a  and  a  simple  continuous  area  of  100-200 m of t h e  the  flow  channel and  then  Assuming that t h i s behaviour  is a  of t h e p r o p e r t i e s of  the  outfall  flow w i t h i n the c h a n n e l ,  it  s u g g e s t e d t h a t t h e d e c r e a s e i n c r o s s - s e c t i o n i s p r i m a r i l y due entrainment  and  consequent  energy through channel outfall  r e g i o n may  The  tailing  at  the  for  deposit  the  12-44  flow.  The  surges,  must be  1  are  remainder  from  the  increase a  tailing to  assumed  estimated  be to  recurrence  i s consistent with t h e c o r e s , and  removed f r o m t h e  out  levees  the  and  near jump.  a distal  zone  change i n v o l u m e of  zones g i v e s a  estimated is  The  i n the  hydraulic  i s d i v i d e d into a proximal  i n t h e two  kg s "  d. T h i s  while  t h e meander r e a c h .  g i v i n g an  obtained  overspill,  mass t r a n s p o r t of  this,  6-7  of  l o s s o f m a t e r i a l and p o t e n t i a l  i n d i c a t e t h e p r e s e n c e of  deposit  end  tailing  for  the  size  a s y n t h e s i s of t h i s m a t e r i a l i s a c h i e v e d  w i t h i n the channel.  of  during  coefficient  s e d i m e n t b u d g e t b a s e d on analytical  processing  (a) t h a t t h e mean p a r t i c l e  reflection  Finally,  to  digitally  400-600 m a t t h e e s t i m a t e d  d u r i n g a 2 min  is  after  figure  of  240  of t h e p r o x i m a l carried be  d  zone.  Of  turbidity  for these range  s"'  continuous  c a r r i e d by  interval 2-5  by  kg  the  of  events values  w i t h t h e amount o f m a t e r i a l w h i c h of the upper  the o b s e r v e d r a t e s of a c c u m u l a t i o n  there.  reach  to  account  250  Biblioqraphy A c k e r s , P. a n d F. G. 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(1977) Diatom s u c c e s s s i o n i n t h e f o r m a t i o n of a n n u a l l y laminated sediment i n L o v o j a r v i , a small eutrophicated lake. Annales B o t a n i c a F e n n i c i 14 , 143-148. S i m p s o n , J . E. (1969) A c o m p a r i s o n between laboratory and a t m o s p h e r i c c u r r e n t s . Q u a r t . J . Roy. M e t . S o c . , 95, 7 5 8 - 7 6 5 .  density  S i m p s o n , J . E. (1972) Effects of the lower boundary on t h e h e a d o f a g r a v i t y c u r r e n t . J . F l u i d Mech., 5 3 , 7 5 9 ^ 7 6 8 .  264  S i m p s o n , J . E., D. A. M a n s f i e l d a n d J . R. M i l f o r d ( 1 9 7 7 ) I n l a n d p e n e t r a t i o n of sea-breeze f r o n t s . Quart. J . M e t . S o c . , 103, 47-76.  Roy.  Smayda, J . J . ( 1 9 7 0 ) The suspension and s i n k i n g of p h y t o p l a n k t o n i n t h e s e a . O c e a n o g r a p h y a n d M a r i n e B i o l o g y A n n u a l R e v i e w , 8, 353-414. S m i t h , J . N . a n d A. 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T e c h n o l . , No. 7, T o k a i U n i v . , 191 . T u c k e r , D. G. a n d B. K. G a z e y (1966) A p p l i e d Underwater A c o u s t i c s . Pergamon  P r e s s , 244 p p .  T u r e k i a n , K.K. a n d J . K . C o c h r a n „(1978) Determination of marine chronologies using radionuclides. In J.P. R i l e y a n d R. Chester C h e m i c a l O c e a n o g r a p h y , 7, ( 2 n d e d i t i o n ) , 3 1 3 - 3 6 1 . U r i c k , R. J . ( 1 9 4 8 ) The a b s o r p t i o n of p a r t i c l e s . J ^ Acoust.  mud 179-  sound i n suspensions S o c . Am., 2 0 , 2 8 3 - 2 8 9 .  of  natural (eds.),  irregular  W a l d i c h u c k , M. a n d R. J . B u c h a n a n (1980) S i g n i f i c a n c e of environmental changes due t o mine waste d i s p o s a l i n t o Rupert I n l e t . F i s h e r i e s and Oceans Canada and B r i t i s h C o l u m b i a M i n i s t r y o f E n v i r o n m e n t , 56 p p . W a l k e r , R. G. (1967) Turbidite sedimentary structures proximal and d i s t a l environments.  and t h e i r r e l a t i o n s h i p t o J ^ Sed. P e t . , 37, 25-43.  W a l k e r , R. G. (1973) M o p p i n g u p t h e t u r b i d i t e m e s s . I n : R. N. G i n s b u r g Evolving Concepts in Sedimentology, Johns U n i v e r s i t y P r e s s , B a l t i m o r e , Md., 1 - 3 7 .  (Editor), Hopkins  266  W a t s o n , J.D. a n d R. M e i s t e r ( 1 9 6 3 ) ' Ultrasonic absorption i n water c o n t a i n i n g plankton s u s p e n s i o n . J ^ A c o u s t . S o c . Am., 35, 1584-1589. W e a s t , R . C , ed. (1978/1979) Handbook o f C h e m i s t r y a n d P h y s i c s . Ohio.  CRC  Press,  Cleveland,  Wenz, G. M. ( 1 9 6 2 ) Acoustic ambient n o i s e i n t h e o c e a n : S p e c t r a and J . A c o u s t . S o c . Am., 34, 1936-1956. Weston, D . E . (1958) O b s e r v a t i o n s on a scattering Deep-Sea R e s . , 5, 4 4 - 5 0 .  layer  at  the  in  sources.  thermocline.  267  Appendix 1 The S c a t t e r e d Wave A1.1  The I s o t r o p i c (n=0) Term Under t h e c o n d i t i o n s s p e c i f i e d a t t h e e n d o f  and  using  (2.50),  the equations  section  ( 2 . 4 8 ) become, w i t h  2.2,  n=0,  (a) xF'+ t B h J ( t ) =A'x' j ' ( x ' )+B't' j ' ( f ) 0  (c)  0  F + brBh (t)=biA'j (x* )+biBj (t') b b b 0  0  c  (d)  0  c  c  B t h J ( t ) = K ' b ^ t ' j„' ( f ) B' L Kb  (A1)  T  (e)  F+4xF'+B[hit)+4th^(t)] s s 2  =  2  P„'2 [ A ' [ S J J j ( x ' )+2x' j ' ( x ' ) ]+B' [ s l ! j ( f ) + 2 t ' ] ' ( f ) ]] p,s' [ 2 2 J o  0  e  0  2  where  the  recurrence  relation  for  j " has  s u b s c r i p t o h a s been d r o p p e d f r o m t h e unknown -iuA' all  and  used.  The  coefficients  and  - i u B ' have been r e p l a c e d by A' a n d B'. I n t h e s e  future variants  letters  been  of  the  equations  (2.48),  a,b,c,d,e,f r e f e r to the a p p r o p r i a t e  ( 2 . 4 8 ) . The  following operations  (e1)=(e)-4(a)/s (cl ) = ( c ) b / b c  the  parent  and  bracketed equation  in  a r e p e r f o r m e d on ( A l )  2  T  (e2)=(e1)-(c1) Then s u b s t i t u t e (d) i n ( a ) and Dropping  b /b c  T  relative  (c2)/(e3), dropping  b ' /b\ c  ( d ) to  obtain  t o 1 i n (e2) g i v e s ,b /b c  T  relative  ( a l ) and  (c2).  ( e 3 ) , and t h e r a t i o  t o 1, g i v e s  (c3)  268  (al)  x F ' = A ' x ' j ' ( x ' )+B' t ' j ' ( f ) ( 1-K'b; ) \ Kb j a  T  B'(-1+K'tanrf.(t' ) - b p ' 2 f - s _ ^ + 2 t a n < ( t ' )) +bc_4tan>e(t' )] I K tanV(t) b> s' \ 2 / b 's J  (c3)  0  t  2  2  0  =A' ( - j . ( x ' ) ) f b  A'2  c  (-j (t'))(b 'p T  0  (e3)  F = A"  I  2  fs'  +2tan* (x') )- 4 b t a n ^ U ' s b;  2  o  s' V 2 2  0  si 2  ft' 2  T  2  c  , 2  )+W b; (A2)  j ( x ' ) + 2 x ' j ' ( x ' ) - 4 x ' j ; ( x ' )-b2 j ( x - ) o  0  0  "s_i j (t' )+2t'j; ( f) -4t.'j '(t')-b^j (t')' 2 s * b 2  o  0  o  2  r  where  tan y (x)«-xh;(x)/h Cx) n  and  tanc* (x) i s defined  as i n (2.7).  n  Before the  (A3)  n  passing to the long-wavelength  inviscid,  non-conducting «3  ( s , t , f ,b ,b^ — T  ). In t h i s  case,  case  limit,  note  (/* K,K' — or  (c3) reduces  to  that  in  0),  and  B'=0,  and  (a1 ) a n d ( e 3 ) t o xF'« F  A'x'jj(x')  =  A'(^_2  The  r e a d e r may  s' i 2  ( x ' ) +2x- j ; ( x ' )  2  i  2  verify  o  that  A1.2 L o n g - W a v e l e n g t h L i m i t In the  limit  the  this  (n=0)  long-wavelength  t o ( A 2 ) , and t a k i n g  substituting  f o r B'  from  i s the appropriate l i m i t .  limit,  x a n d x' a r e « 1 . A p p l y i n g  the r a t i o  (c3) y i e l d s  of (a1)  and  ( e 3 ) , and  269  tan$ =xF'/F  ( )  0  A 4  3s' / l - K ' b ; | f b - p „ ) 4x' V K  =xl_ f s ' /1-K'tan«;(t' )\ + 4 b j p ; t a n < ( t ' ) Ktanr.(t) j b; p 2  2  2  +K'b'b1'  bJUc fW t  r  c  K  b b 'j.  i n t h e c a s e of  solid  2  0  T  £  A'f-1+4x' ) f s ' f 1 - K ' t a n < ( t ' )]\ -4 b ' p.' t a n ^ ( t ' ) £V Is^JL V KtanHt) ~ b ^ 2  2  /J  where t h e f u r t h e r scatterers, are  approximations, permitted  that  | k '/k | , | k;/k c  e  s  |«1  5  (A5)  and  o . i < f.'/fi. <10 so  t h a t t h e p r o d u c t s o f p ' /p 0  b /b{, c  k ^ / k , k ' /k 2  2  2  5  2  may  a l s o be a s s u m e d s m a l l . The  Po' / Po a r e r o u g h e s t i m a t e s The  result  the l i m i t  K =0,  tan $  0  or i t s i n v e r s e and t h e q u a n t i t i e s  0  bounds  on  only.  (A4) i s i n d e p e n d e n t o f t h e f l u i d  viscosity.  In  i t reduces to  = x' f J f-1+4x' i] 3 I Ttl 3s' /J 2  2N  P  1  2  w h i c h t h e r e a d e r may I t may with  verify  i s identical  a l s o be shown t h a t  Allegra  and H a w l e y ' s  the e q u i v a l e n c e xF'/F  the  result  (10) a n d  i s the f o l l o w i n g .  t o (2.8) w i t h (A4)  ( 1 2 ) . One  way  is  to demonstrate  Let  (2.50),  A- -(N+x D/3)/[N-i(N+D)/xj  (A6)  2  the s ' / s 2  (10), m u l t i p l y i n g  2  terms  i n the denominator  and d i v i d i n g  -0,'K' t a n * ( t ' ) D  ,oK t a n d t ) h j t ) . a  compatible  =N/D  in which case, using  Dropping  n=0.  by  of  their  equation  270  and  using  dropping -tan^ x /3  (A6) t h e e q u i v a l e n c e  i s readily  the (small) imaginary  established. Finally,  p a r t s o f x i n A4,  _3_tanc| + 1 x . tanc^, -1 0  2  0  3  =x' f s' f\ - K ' t a n * . ( t ' x I V KtanY (t) 2  +4b ' p.'x t a n ^ t ' ) Q ] b' P.X'  2  2  1 + x p ' f 1 -4x'2 x ' /Q, 3s 2  2  2  n  2  0  c  I  1 -K' t a n o( (t K tanY(t)  c  2  T  tan<(t' )  0  /J  (A7a)  b 'A T  where Q=ils 4x  and  ' 2 A _ 1-K'b :  Kb  T  'V be  T  1  /V b '  T  c  relative  2  the the denominator. Equations  Hawley  which  to  1  have  been  dropped  (12) and (14) i n A l l e g r a and  ( 1 9 7 2 ) r e d u c e t o (A7) i d e n t i c a l l y .  If 1  (A7b)  r  P.*  c  where t e r m s o f o r d e r x '  from  K ' br' b x I 2 2 Kb b'x  +  "  | t ' | and | 1 1 » 1 , then t a n «.(t' ) = 1 + K ' c r = 1 + Ko-' K tan x ( t )  p.' EL C  K'  i s close  to  1 f o rthe cases  being considered. I f i t i s  f u r t h e r assumed t h a t s* » 4 | b ' t a n * ( t ' ) / b ; | 2  c  then  we o b t a i n  ( 2 . 5 4 ) . Now, u s i n g  b '=-(y'-l ) ^ / ( 2  c  the assumption  *c,' ) , b = c ' k ; / ' c , ' 2  | t'|»1,  g e n e r a l l y . When valid  general case,  2  2  /3  ( A 8 ) may be r e w r i t t e n , a p p r o x i m a t e l y , a s s 4x  t 2  again  2  T  W - 1 ) tan«C(t' ) When  (A8)  o  2  I  2  ^ 0.1  t a n tf (t' ) ^ i t ' o  and  the  assumption  holds  | t ' | « 1 , t a n <*( t ' ) ~ t ' / 3 a n d t h e a s s u m p t i o n i s 2  e  s i n c e f o r most s o l i d s writing  t'= ^ ( 1 + i ) ,  y ' i s v e r y c l o s e t o 1. I n t h e  271  tan * ( t  ) = 1-t'cot ( t ' )  1  0  = from which  i t can  approximation 20%  A 1  •  and  3  be  | t ' | = 1 , 3,  Dipole  (n=Q  Dropping the terms,  (2.50),  1  the  | t a n o( (t' o  and  | t ' | . The  is  a  good  error is  67%,  10.  1  boundary c o n d i t i o n s ,  A,' = ( - i u j ) A '  from  of  )| ~ | t'|  Term  thermal  setting  subscript  shown t h a t  even f o r s m a l l v a l u e s  5% a t  The  1 - ( j ' - i j ) [ sinh2rf + isin2:f 3 [ cosh2^ - cos21 ]  the  and  the  C' = ( - i u j ) C ' ,  undetermined  B  and  dropping  coefficients,-  and  B' the  using  ( 2 . 4 8 ) become  (a) xF'+2Ch,(s) = A ' x ' j , ' ( x ' ) + 2 C j,(s') (b)  F+CfhJsJ+sh,' ( s ) ]=A' j,(x' ) + C  [ j,(s' )+s' j ; ( s ' ) ]  (e) s i F - 2 F + 2 x F ' + 2 C [ h , ( s ) - s h ; ( s ) ]  (A9)  = yo.'s'jx' A' [ V _ j , ( x ' ) - j , " ( x ' ) ] - 2 C AS' t 2/*'  [s'j.' (s' )-j,(s' ) ]  2  2  (f) xF'-F+Cs_ h"(sWs 2  Perform  the  2  (A' f x ' j,' ( x ' ) - j ( x ' ) ] + C ' s l i j " ( s ' )  following operations  on  (A9)  (e1)=(e)-2(f) (b1)=2(b)-(a) (f1)={2(f)+(b1)+si(e1)-(a)}2s2  2  (b2) = (b1) + 2 ( a ) - 2 ( e 1 ) (e2)=(e1)-(f1) which  yields  (a)  xF*+2Ch,(s) = A ' x ' j , ' ( x * ) + 2 C  j,(s')  (b2)  C [ s h , ' ( s ) - h , ( s ) ] = A' j,(x' ) ( i - ^ U c s ' j , ' ( s ' ) + j,(s' )  1-2  )  272  (e2) • C h ( s ) = f t f 2 A ' [x'j; U ' )-j,(x' ) ](_£*_-JL_)  ( A 1 0 )  L  1  M  l :s  2  s  P  +C'r-i"(s' )-2A  t  2  i  [ s ' i . ' ( s ' )-i,(s' ) ]]]  (f 1 ) F= :2 A'fs'M.Cx' )+2x' j ' ( x ' ) - 2 j , ( x ' ) - 2 a s' [ x ' j,' ( x ' )-j,(x' ) ]' f>,s'\ [2 ls J 2  p  2  p  + C ' 2 [ s ' j,' ( s ' ) - i , ( 5 ' ) ] | - H 0 . s ' | j J Note  that  reduce  i n the inviscid  limit,  t o t h e a p p r o p r i a t e form  s -~ <=o  and these  equations  f o r tan$=xF'/F.  A1.4 L o n g - w a v e l e n g t h L i m i t (n=1) Take t h e r a t i o of  order s  , 2  /s  2  (b2)/(e2) and s o l v e f o r C ,  relative  (fj^-A  t  C'=-A'  +  2x' [ t a n2^ ( s ) + 1 ] \  ss' 2  " j , ( s ' ) | 2 ^ - 1 j + 3 _ [ t a n T ( s ) + 1 ]j  j  (e2) i n (a) and ( f l ) and take t h e r a t i o  _£_[tanY,(s) + 1 ] + 2(^-1) t a n $ =xF_;=^ \& L F 2fp, -1) + t a n / , ( s ) + 1 and  terms  t o 1,  j , (x')Kv ;  Substitute  dropping  (All)  to get (A12)  finally, {_&_-!) [ t a n y , ( s ) + 1 ]  (A13)  tang, = I pJ I . x /3 ^ + 2 j [ t a n r , ( s ) + 1 ]+6 ^ - 1 J 3  which  i sequivalent t o Allegra  inviscid  limit,  s - * « s  and  - t a n 17, = ( po ~ Po ) x /3 (p. +2p: ) 3  as r e q u i r e d .  and Hawley's r e s u l t  (15).In the  273  A1.5  L i s t  of  Symbols  A  shear  a  particle  radius  specific  heats  C  C  c c  s  wave  vector  potential  phase  speed  of  compression  phase  speed  of  shear  wave  wave  c,  Equation  d.  viscous  boundary  layer  thickness  d  thermal  boundary  layer  thickness  T  E  (2.33)  internal rate  *j  F„ h „ , ( j  n  ) , [n  K  n  ]  energy  of  strain  Equation  (2.50)  spherical  Hankel,(Bessel),[Neuman]  thermal  k  c  P  n  p  , k  T  , k  s  tensor  conductivity  compression, Legendre  thermal  and shear  wavenumbers  polynomials  pressure  r,--.  radial  coordinate  S  stress  tensor  s  k  T  functions  5  a  temperature  t  k a  u;  component  of  strain  Vj,  component  of  rate  x  k a  T  c  of  in  solid  strain  in  fluid  attenuation Equation  coefficient  (2.7b)  coefficient of.thermal Equation  expansion  (2.7c)  r a t i o of s p e c i f i c Equation  heats  (A.3)  thickness  of s p h e r i c a l  Equation  (2.7a)  Kronecker  delta  shell  tensor  volume f r a c t i o n of suspended strain  solids  tensor  p h a s e o f n t h p a r t i a l wave ( e q u a t i o n ( 2 . polar  (scattering)  angle  compressibility  of  fluid  compressibility  of  solid  Lame c o n s t a n t Lame" c o n s t a n t shear  viscosity  density thermal d i f f u s i v i t y azimuthal  (Equation  (2.63))  angle  scalar potential  f o r compression  scalar potential  f o r thermal  angular Equations  frequency ( 2 . 6 ) and ( 2 . 9 )  waves  waves  275  APPENDIX 2 SPECIAL-PURPOSE INSTRUMENTATION The n a t u r e o f t h e e n v i r o n m e n t of  AND  itself  EQUIPMENT  l e d t o the development  s e v e r a l new a p p r o a c h e s t o o l d p r o b l e m s , a n d t h r e e o f t h e more  useful are detailed  below.  A2.1 A C o m b i n a t i o n S a m p l e r  f o r High Suspended Load  The s a m p l e r i s shown i n F i g u r e  105. I t c o n s i s t s o f a 250 ml  F r o e s c h e - t y p e PVC s a m p l e r f i x e d t o a Closure  is  effected  by  means  rubber tubing connecting These a r e h e l d loop  around  conventional  of t h e t e n s i o n  two  spherical  NIO  bottle.  i n the s u r g i c a l  rubber  end-caps.  i n t h e open p o s i t i o n v i a two n y l o n l a n y a r d s a  p i n . The  attached t o the lower virtually  the  Environments  end  simultaneous  pin  i s w i t h d r a w n by a t h i r d  cap  of  filtration.  Fig. 105. bottle.  Combination  NIO  bottle,  lanyard allowing  c l o s u r e o f t h e two s a m p l e r s . The  sample i s d r a i n e d t h r o u g h a f u n n e l subsequent  the  into  250 ml s u s p e n d e d  a  300  solids  ml  which  entire  bottle  for  s a m p l e r a n d NIO  276  The long  s a m p l e r was  filtration  loads greater obtaining (Fig.  time  instantaneous  87).  Neither  estimates  this  mg  a  thereby  Kullenberg-type  study,  Chapter  and  5.  D e p t . of  I  l "  problem  A M o d i f i e d Boomerang A  two  and  1  can  problems:  be  the  sample - the  are  inaccurate.  plume  suspended  by  load  Corer corer  grateful  Geological  of  solved s a t i s f a c t o r i l y  was  used i n the  i t s s h o r t c o m i n g s have a l r e a d y am  the  requirement  i n the d i s c h a r g e  larger too  (1)  samplers i n suspended  (2)  density estimates  from  obtained  to solve  using conventional  t h a n a few  drawing a l i q u o t s  A2.2  designed  to  Sciences,  R.  D.  for  initial  phase of  been m e n t i o n e d  in  MacDonald, then w i t h  the  suggesting  the  following  m o d i f i c a t i o n s t o t h e Boomerang c o r e r . Boomerang of the c o r e r The  core  corers  i s e x p e n d a b l e and  itself  external  is  flotation  penetration. flotation  are normally  For  is  to  the  surface  released  winch-coring,  were removed, and  the  the  in i t s liner  mechanically release  mechanism  and  t h u s a l l o w c l o s u r e of the b u t t e r f l y v a l v e t o s e a l the  The  advantages  d i s t a n c e between the weight-stand (1) t h e while  of  from the this  t o p of  the  the  valve  assembly top  in a  could  be  vertical  system, liner  aside and  removed f r o m t h e position  of  bottom. from the the  base  shorter of  ( s e e C h a p t e r 5 ) , were t h a t :  core  and  r e p l a c e d by a P e d e r s e n g r a b r e l e a s e .  used to withdraw the p i n i n  withdrawal  by  after  latter  before  body  bottom.  The  the core  was  r e m a i n s imbedded i n  carried which  f r e e - f a l l d e v i c e s . The  t o p of  without  the  breaking  corer the  the  277  seal. (2) t h e  c o r e c a t c h e r c o u l d be  removed and  core capped without b r e a k i n g the (3) c o r e c a t c h e r s and adhesive  tape  valve  to the core l i n e r ,  with a fresh liner  Fig. 106. UBC 5 m outboard engine.  A2.3  usually  launch:  The  UBC  L a u n c h and  The  l a u n c h i s shown  are  which  attached can  and  reloading  took  l e s s than a  fibreglas  the Transducer in  Fig.  the  seal.  assemblies  a d v a n c e . R e m o v a l of a c o r e  t h e b a s e of  by  be done i n the  corer  minute.  construction, inboard-  Mount  106.  It  was  modified  for  oceanographic  work by m o v i n g t h e c o n t r o l c o n s o l e and w i n d s h i e l d  0.45  f o r w a r d t o p r o v i d e more w o r k i n g  m further  starboard  davit  s t r e n g t h e n i n g the standing-room  winch  hull  shelter  a z i p p e r e d door. and  and  Only  with i n two  (port  side)  fibreglas.  were The  space  aft.  mounted canopy  section  i t p r o t e c t s t h e c o n t r o l l c o n s o l e and  i s shown i n F i g . electronic  after  provides  s e c t i o n s s e p a r a t e d by a p a n e l  the forward  The  with 106,  instruments  278  (acoustic  sounder  transceiver  the  recorder,  tape-recorder)  while  shown) e n c l o s e s  the e n t i r e after-deck,  panels  using  and  oscilloscope  w i n c h . The o t h e r  The  faired  mounting  is  of laminated  bolted to a faired  a l u m i n u m p i p e . The l a t t e r the  port  transducer  gunwale  wood p r o t e c t s t h e  strut  f r o m t h e main r o t o r - b l a d e  of  zippered  be u s e d .  f o r t h e 192 kHz t r a n s d u c e r  the p o r t a b l e Ross L a b o r a t o r i e s a c o u s t i c sounder 107. A f a i r i n g  s e c t i o n (not  but because  i n t h e s i d e s t h e w i n c h a n d d a v i t may s t i l l  of  and  used  with  i s shown i n F i g . transducer  which  ( F i g . 107a) c o n s i s t i n g o f a s e c t i o n a  helicopter  and  a  length  f i t s a c o l l e t - c h u c k assembly  ( F i g . 107b). S t a y s  run f o r e - a n d - a f t  of  bolted to from t h e  fairing.  F i g . 107a. (a) T r a n s d u c e r f a i r i n g a n d 19.6 cm d i a m e t e r 192 kHz transducer (solid dark circle). (b) T r a n s d u c e r f a i r i n g w h i l e u n d e r way. W i n c h e x h a u s t p i p e a l s o e v i d e n t .  279  APPENDIX