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A preliminary study of the regional groundwater flow in the Meager Mountain geothermal area, British… Jamieson, Gordon Reginald 1981

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A PRELIMINARY STUDY OF THE REGIONAL  GROUNDWATER FLOW I N THE  MEAGER MOUNTAIN GEOTHERMAL AREA, B R I T I S H COLUMBIA by GORDON REGINALD B.Sc,  The U n i v e r s i t y  A THESIS SUBMITTED  JAMIESON o f W a t e r l o o , 1979  I N PARTIAL FULFILLMENT OF  THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF GEOLOGICAL  We a c c e p t t h i s  SCIENCES  t h e s i s as 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 May 1981 ©  G o r d o n R e g i n a l d J a m i e s o n , 1981  In p r e s e n t i n g  this  thesis i n partial  fulfilment 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 study.  agree that p e r m i s s i o n f o r extensive for  financial  copying or p u b l i c a t i o n of this  gain  shall  Department  of  ert-b&tett/  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  12/79)  thesis  Iff/  It i s thesis  n o t b e a l l o w e d w i t h o u t my  permission.  DR-fi  I further  s c h o l a r l y p u r p o s e s may be g r a n t e d by t h e h e a d o f my  understood that  Date  make  copying of t h i s  department 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 . for  shall  -^£s^<J<?i^&  Columbia  written  ABSTRACT The  Meager M o u n t a i n g e o t h e r m a l  north-northwest  area  of V a n c o u v e r , B r i t i s h  t y p e s of e x i s t i n g and  ter  f l o w regime of the study  site.  was  carried  the  to determine  groundwater flow c h a r a c t e r i s t i c Meager M o u n t a i n s i t e and  basement r o c k s t h r o u g h  thickness  has  be  Apart  C r e e k H o t s p r i n g s and  comprised  groundwater  ash.  mainly  of ande-  I t became a c t i v e older  in  granitic  Subsequent a l p i n e variable  bottom.  i n t e r m e d i a t e e l e v a t i o n i n the few  f o r the mountain  s p r i n g s at higher e l e v a t i o n s ,  by  unconsolidated deposits.  Pebble  calculations  determinations t o 17%  system.  Meager  Creek H o t s p r i n g s are both l o c a t e d  d i s c h a r g e area near stream  Water b a l a n c e  c a t e t h a t 14.5  range of r e g i o n a l  i s b e l i e v e d t o be c o n f i n e d t o t h e p o r t i o n  of the v a l l e y c o v e r e d  baseflow  groundwa-  area.  t h e T e r t i a r y and  from a v e r y  suggested  hydro-  modelling  shown t h a t t h e most l i k e l y p o s i t i o n  the d i s c h a r g e area  and  the  d e p o s i t e d u n c o n s o l i d a t e d d e p o s i t s of  w a t e r t a b l e i s a t an  in t h i s  i n the  which i t erupted.  i n the v a l l e y  I t can  system.  feasible  i s a volcano  the P l i o c e n e , f r a c t u r i n g  evaluate  km  Various  Mathematical  d a c i t e f l o w s , b r e c c i a s and  glaciation  Columbia.  f i e l d - g e n e r a t e d g e o l o g i c a l and  g e o l o g i c a l d a t a were e m p l o y e d t o f u l l y  out  i s s i t u a t e d 160  level.  f o r the L i l l o o e t  River basin  i n t h e Meager C r e e k b a s i n  of t h e t o t a l  precipitation  indi-  enters  the  Mathematical modelling groundwater d i s c h a r g e vity  distribution  indicate that  i s d e p e n d e n t on t h e h y d r a u l i c  and water t a b l e c o n f i g u r a t i o n  dent of t h e depth of t h e flow  lated  t o be 1 4 - 1 8 % , c o r r e l a t i n g w e l l w i t h  baseflow c a l c u l a t i o n s .  timate  the hydraulic  the Meager M o u n t a i n The  t o 10"  8  2  m/s  to 10"  5  as  m/s  hydraulic  hydraulic  in the v o l c a n i c s  and i n t h e basement.  lic  8  7  m/s f o r  c o n d u c t i v i t y may be a s  i n the volcanics  work a t t h e Meager  the i n i t i a t i o n  i n the south r e s e r v o i r area, rocks,  to 10"  10"  rocks.  conductivity values probably  Recommendations f o r f u t u r e  volcanic  deposits,  c o n d u c t i v i t y may be a s much  than the v e r t i c a l  include  4 , 5  found  t h a n t h e h o r i z o n t a l i n t h e basement  Similar vertical  balance  materials i n  c o n d u c t i v i t i e s were  hydraulic  The h o r i z o n t a l h y d r a u l i c  geothermal area  were u s e d t o e s -  of the v a r i o u s  f o r the unconsolidated  The v e r t i c a l  5 times greater  balance  system.  much a s 5 t i m e s g r e a t e r rocks.  the water  The s i m u l a t i o n s  f o r t h e basement r o c k a n d 1 0 "  volcanics.  but indepen-  t h e groundwater zone i s c a l c u -  conductivity  representative  t o be 1 0 "  conducti-  The p e r c e n t a g e o f  precipitation  the  entering  region.  total  and  t h e amount o f  Mountain  of a d e t a i l e d water  a f r a c t u r e survey of t h e  continued mathematical modelling,  c o n d u c t i v i t y measurements  exist  i n deep d r i l l  holes.  and hydrau-  TABLE OF  CONTENTS  ABSTRACT L I S T OF TABLES L I S T OF ILLUSTRATION ACKNOWLEDGEMENTS  ii vi vi x  1.  INTRODUCTION Objectives L o c a t i o n And A c c e s s P r e v i o u s Work B.C. H y d r o And Power A u t h o r i t y E n e r g y M i n e s & R e s o u r c e s Canada  ..1 1 4 9 12 13  2.  PHYSICAL SETTING Regional Geology L o c a l Geology Physiography Thermal Springs Cold Springs  16 16 18 23 25 28  3.  FUNDAMENTALS OF GROUNDWATER FLOW D a r c y ' s Law The P o r o s i t y R e l a t i o n s h i p W i t h H y d r a u l i c  31 31  Conductivity  H o m o g e n e i t y And H e t e r o g e n e i t y Of H y d r a u l i c Conductivity I s o t r o p y And A n i s o t r o p y Of H y d r a u l i c C o n d u c t i v i t y Water T a b l e Flow Nets R e c h a r g e A r e a s , D i s c h a r g e A r e a s , And G r o u n d w a t e r Divides S t e a d y S t a t e F l o w Vs T r a n s i e n t F l o w The E f f e c t Of The H y d r o g e o l o g i c E n v i r o n m e n t On The G r o u n d w a t e r Regime 4.  PRELIMINARY WATER BALANCE P r e c i p i t a t i o n And T e m p e r a t u r e Evapotranspiration Runoff Water B a l a n c e  HYDROGEOLOGY Water T a b l e C o n f i g u r a t i o n H y d r a u l i c C o n d u c t i v i t i e s Of  The  36 ...38 40 40 42 43 46 50 51 54 55 57  5. HYDRAULIC CONDUCTIVITY OF FRACTURED ROCK F r a c t u r e M a p p i n g And D a t a P r o c e s s i n g M e t h o d s Meager M o u n t a i n F r a c t u r e S u r v e y Results Discussion P u b l i s h e d F r a c t u r e P e r m e a b i l i t i e s Of V a r i o u s Rock Types 6.  35  Geologic  Materials  63 64 67 67 70 75 80 82 ..84  Estimates  Of G r o u n d w a t e r R e c h a r g e  88  7. GROUNDWATER MODELLING The C o m p u t e r P r o g r a m Simulation Strategy R e g i o n Of F l o w E q u a t i o n Of F l o w Boundary C o n d i t i o n s Hydraulic Conductivity Distribution F i n i t e Element Method Input Data S e n s i t i v i t y A n a l y s e s W i t h FOPS FREESURF1 M o d e l l i n g V a r i a b l e Parameters . F i n i t e E l e m e n t Mesh Results Interpretation  92 93 95 95 97 97 99 101 103 104 108 108 109 110 125  8. CONCLUSIONS AND RECOMMENDATIONS Summary And C o n c l u s i o n Geography Geology Hydrogeology Mathematical Modelling Recommendations  128 128 128 129 130 132 133  APPENDIX I : GLACIAL BASAL MELT FLUX  .•  CALCULATIONS  IN THE MEAGER CREEK BASIN  136  APPENDIX I I : CONTOURED-POLE PLOTS OF FRACTURE APPENDIX I I I MEAGER CREEK APPENDIX I V : MEAGER CREEK  DATA ..138  : RIVER STAGE MEASUREMENTS AT HOTSPRINGS BRIDGE, 1979 DISCHARGE CALCULATION AT THE STAGE S I T E , DEC. 1 0 , 1979  152 156  APPENDIX V: DECEMBER DAILY DISCHARGES OF THE LILLOOET RIVER NEAR PEMBERTON ( 1 9 7 7 - 1 9 7 9 )  158  REFERENCES  160  ,  vi  L I S T OF TABLES  Table  Page  4.1 P r e c i p i t a t i o n a n d t e m p e r a t u r e d a t a a t P e m b e r t o n and  Bralorne  53 5.1 O r i e n t a t i o n  v a r i a t i o n s of j o i n t  5.2 A v e r a g e o r i e n t a t i o n o f j o i n t and  71 5.3 J o i n t  a p e r t u r e v a r i a t i o n s 72 5.4 A v e r a g e s p a c i n g  72 5.5 Summary various  of measured h y d r a u l i c  r o c k t y p e s 78 7.1 Summary  simulations in  sets  106 7.2 H y d r a u l i c  FREESURF1 s i m u l a t i o n s  ductivity  distributions  simulations  124  Meadows sets  spacing  and a p e r t u r e  conductivity values f o r  of s e n s i t i v i t y  analysis  c o n d u c t i v i t y d i s t r i b u t i o n s used  112 7.3 R e c h a r g e a n d h y d r a u l i c with  70  a set discharge  con-  i n FREESURF1  vii  L I S T OF  ILLUSTRATION  Illustration  Page  1.1  L o c a t i o n of Meager M o u n t a i n g e o t h e r m a l  1.2  River, glacier,  1.3  P h o t o g r a p h of Meager and  P l i n t h peaks  7  1.4  Hotsprings  and  locations  9  1.5  Drill  locations  2.1  Regional  hole  springs  and  5  m o u n t a i n peak d e s i g n a t i o n  reservoir  geology  area  and  11 l o c a t i o n of  in southwerstern  British  thermal Columbia  2.2  L o c a l geology  2.3  P h o t o g r a p h of t h e Meager C r e e k v a l l e y  17  o f t h e Meager M o u n t a i n a r e a  20  i n the  South R e s e r v o i r area  24  2.4  P h o t o g r a p h of the r a p i d l y e r o d i n g v o l c a n i c s  2.5  L o c a t i o n of m a j o r v e n t s a t Meager C r e e k  24  Hotsprings 2.6  27  L o c a t i o n of m a j o r v e n t s a t p e b b l e  creek  Hotsprings  27  2.7  Cold spring l o c a t i o n s  3.1  Experimental  apparatus  29 f o r the  illustration  of  D a r c y ' s law 3.2  H y d r a u l i c head, p r e s s u r e for  32 head and  e l e v a t i o n head  a l a b o r a t o r y manometer  3.3  Layered  3.4  Four p o s s i b l e combinations and  6  h e t e r o g e n e i t y and  anisotropy  32  trending heterogeneity of  37  heterogeneity 37  viii  3.5  R e l a t i o n s h i p between l a y e r e d  heterogeneity  and a n i s o t r o p y  41  3.6  groundwater  flow at various boundaries  3.7  Two-dimensional groundwater  3.8  E f f e c t o f t o p o g r a p h on g r o u n d w a t e r  3.9  E f f e c t o f g e o l o g y on g r o u n d w a t e r  4.1  Location  of d a t a g a t h e r i n g  in the L i l l o o e t 4.2  flow net  44  flow patterns  flow patterns  River area River  bottom  56  Mean o f mean d a i l y  5.1  Location  discharge  forLillooet  6.1  General groundwater  6.2  Water t a b l e e l e v a t i o n and seepage  River  of f r a c t u r e survey s i t e s flow  61 68  i n Meager M o u n t a i n  81  face  development Equivalent  47  52  4.3  6.3  44  stations  H y d r o m e t e o r o g i c a l regime of the L i l l o o e t and v a l l e y  41  83  hydraulic conductivity i n layered  volcanics  87  6.4  C r o s s - s e c t i o n o f Meager C r e e k a t s t a g e l o c a t i o n  6.5  Summary o f h y d r o g e o l o g y on t h e s o u t h s i d e - o f Meager M o u n t a i n  91  7.1  Region of flow  7.2  L i n e of s e c t i o n f o r r e g i o n  7.3  Geological configurations simulated  7.4  g r o u n d w a t e r movement i n t h e r o c k unconsolidated  87  f o r mathematical modelling of flow  96 100  and i n t h e  material  102  7.5  G e o m e t r i e s u s e d i n FOPS s i m u l a t i o n s  7.6  Finite  e l e m e n t mesh u s e d  96  i n FREESURF1  105  ix  simulations 7.7  Equipotential  110 pattern  f o r FREESURF IA and  FREESURF I B c a s e s  113  7.8  Equipotential  pattern  f o r FREESURF I C c a s e s  114  7.9  Equipotential  pattern  f o r FREESURF 2  cases  115  7.10  Equipotential pattern  f o r FREESURF 3  cases  116  7.11  Equipotential  f o r FREESURF 4  cases  117  7.12  P r e s s u r e v s d e p t h g r a p h o f minimum  pattern  water t a b l e e l e v a t i o n examples 7.13  121  P r e s s u r e v s d e p t h g r a p h o f maximum water t a b l e e l e v a t i o n  examples  122  X  ACKNOWLEDGEMENTS I would  like  Dr. A l l a n F r e e z e course of t h i s script.  t o e x p r e s s my d e e p a p p r e c i a t i o n t o f o r h i s support and guidance  study and f o r h i s c r i t i c a l  participation  Mathews  review of t h i s manuscript  on t h e t h e s i s e x a m i n a t i o n  I w i s h t o thank D r . Jack Souther Survey  r e v i e w o f t h e manu-  I a l s o acknowledge t h e support of Dr. B i l l  and D r . Tom Brown f o r t h e i r their  throughout the  committee.  of the G e o l o g i c a l  o f Canada f o r h i s s u p p o r t a n d i n v a l u a b l e i n f o r m a t i o n  he g r a c i o u s l y I gratefully assistance  supplied during the early  stages of t h i s  i n the f i e l d  t o thank  o f John  Joe Stauder  Power A u t h o r i t y  Reader,  B r i a n F a i r b a n k , and  of t h e B r i t i s h  Columbia  f o r s u p p l i n g my room a n d b o a r d  Furthermore,  I would  like  P e t e r Read a n d D r . G a r y I would  her  like  gratefully  i n the f i e l d .  Clarke.  t o e x t e n d my t h a n k s t o R o b e r t a C r o s b y f o r  t i o n s o f t y p i n g a t h e s i s on t h e c o m p u t e r . in this  Hydro and  Slaymaker,  k i n d a s s i s t a n c e a n d c o u n s e l on t h e t r i a l s  fting  I would  t o acknowledge t h e h e l p f u l  a d v i c e a n d i n f o r m a t i o n s u p p l i e d by D r . O l a v Dr.  study.  acknowledge t h e k i n d and h e l p f u l c o o p e r a t i o n and  S t u C r o f t o f N e v i n S a d l i e r - B r o w n and Goodbrande L t d . like  and f o r  The e x c e l l e n t  r e p o r t was d r a w n by G o r d Hodge.  acknowledged.  and t r i b u l a dra-  H i s work i s  xi  I w i s h t o thank  a good f r i e n d and  Garven, f o r h i s h e l p f u l this  s t u d y and my  British  s u g g e s t i o n s and  c o l l e a g u e Grant a s s i s t a n c e throughout  a c e d e m i c p r o g r a m a t The  University  of  Columbia.  A s p e c i a l word of t h a n k s the manuscript.  Her  g o e s t o L i n d a Mah,  for typing  c o n s t a n t a s s i s t a n c e i n the f i n a l  pre-  p a r a t i o n of t h i s t h e s i s has make i t s c o m p l e t i o n by t h i s a  reality.  date  1 1  Chapter  1.  INTRODUCTION This thesis  i s an e v a l u a t i o n o f t h e h y d r o g e o l o g y o f  Meager M o u n t a i n  geothermal  p a r t of a j o i n t  s t u d y o f Meager M o u n t a i n  t h e B.C.  area.  The  work done i s a  small  b e i n g c a r r i e d out  H y d r o and Power A u t h o r i t y and E n e r g y , M i n e s  R e s o u r c e s , Canada i n o r d e r t o a s s e s s t h e g e o t h e r m a l potential  the  by  and resource  of the a r e a .  Objectives The  main purpose  of t h i s  study i s to develop a  n a r y m a t h e m a t i c a l model o f t h e r e g i o n a l g r o u n d w a t e r t h e Meager M o u n t a i n will  geothermal  area.  The  m o d e l and  the l i m i t e d  assumptions  system,  is felt  t h a t the m a t h e m a t i c a l model can prove  possible, ties  that  t o a s u i t e of f e a s i b l e  flow f i e l d s .  i n f o r m a t i o n becomes a v a i l a b l e further  The  intent  groundwater  i s b o t h r e a s o n a b l e and  thereby r e d u c i n g the i n f i n i t e  However,  valuable,  information.  i s t o d e v e l o p t h r o u g h m o d e l l i n g a range of  flow c h a r a c t e r i s t i c s  be-  knowledge of the s u b s u r f a c e g e o l o g i c a l  d e s p i t e t h e l i m i t e d amount of f i e l d here  model  t h a t must be made i n t h e  and h y d r o g e o l o g i c a l c o n d i t i o n s a t M e a g e r M o u n t a i n . it  flow i n  mathematical  p r o v i d e o n l y an a p p r o x i m a t i o n o f t h e r e a l  cause of t h e s i m p l i f y i n g  prelimi-  range of As more  physically possibiligroundwater  i n t h e f u t u r e t h e s u i t e can  refined.  I t must be s t r e s s e d  that t h i s  i s a regional  s t u d y of  be  2  groundwater  flow  i n the e n t i r e mountain  resource study at a l o c a l specific  i n c o r p o r a t i o n of heat f l o w  i s beyond  the  t h e scope of t h i s  report.  gebthermal f o c u s on a  must be u n d e r s t o o d . i n the groundwater Heat  flow would  model  slightly  t h e s u b s u r f a c e f l o w p a t h s b u t no s u b s t a n t i a l c h a n g e i n  g e n e r a l f l o w c h a r a c t e r i s t i c s w o u l d be e x p e c t e d .  suggested that the  B e f o r e one c a n  a r e a , t h e s y s t e m as a w h o l e  The  alter  scale.  and n o t a  heat In  future mathematical modelling should couple  flow w i t h the groundwater Chapter  Mountain  cussed.  flow..  1, t h e p r e v i o u s work u n d e r t a k e n  a r e a by t h e B r i t i s h C o l u m b i a H y d r o and  A u t h o r i t y and  It is  i n t h e Meager Power  t h e G e o l o g i c a l S u r v e y o f Canada w i l l  be  dis-  Numerous g e o l o g i c a l , g e o c h e m i c a l and g e o p h y s i c a l  s u r v e y s h a v e been c o m p l e t e d s i n c e In  1973.  C h a p t e r 2, t h e p h y s i o g r a p h y and t h e c o m p l e x  regional  geology are examined.  The  location  o f t h e Meager M o u n t a i n  h o t and c o l d  local  and  p h y s i o g r a p h i c n a t u r e and springs are  also  considered. In  C h a p t e r 3, t h e b a s i c p h y s i c s o f g r o u n d w a t e r  discussed. normal  The m a t e r i a l  i s covered i n greater d e t a i l  i n hydrogeological reports  an u n d e r s t a n d i n g of g r o u n d w a t e r linary In runoff  flow i s  i n an a t t e m p t t o g e n e r a t e  flow a c r o s s the  b o u n d a r i e s o f t h e Meager M o u n t a i n C h a p t e r 4, t h e c l i m a t i c out of the L i l l o o e t  River  than i s  interdiscip-  geothermal  c o n d i t i o n s and  project.  t h e amount o f  b a s i n a r e d i s c u s s e d and a  3  calculation made.  The  total  of a p r e l i m i n a r y w a t e r b a l a n c e f o r t h e b a s i n i s objective  precipitation  i s t o e s t i m a t e t h e p e r c e n t a g e of t h e that e n t e r s the groundwater  system.  The  c h a r a c t e r i s t i c s of the s u b s u r f a c e flow regime are dependent on t h e amount of w a t e r e n t e r i n g  the  system.  I n C h a p t e r 5, s p e c i a l a t t e n t i o n conductivity  of f r a c t u r e d  rock.  F r a c t u r e m a p p i n g and  p r o c e s s i n g methods a r e c o n s i d e r e d . cance  o f t h e Meager M o u n t a i n  To c h e c k  the v a l i d i t y  i s p a i d t o the h y d r a u l i c  The  fracture  r e s u l t s and  survey are  data  signifi-  discussed.  of the s u r v e y , the r e s u l t s a r e compared  w i t h p u b l i s h e d d a t a on t h e f r a c t u r e p e r m e a b i l i t y o f  various  rock t y p e s . I n C h a p t e r 6, a s p e c t s o f t h e h y d r o g e o l o g y a r e e x a m i n e d including tivity  t h e w a t e r t a b l e c o n f i g u r a t i o n and h y d r a u l i c  of the d i f f e r e n t  groundwater  geologic materials.  r e c h a r g e i n t h e Meager C r e e k  The  basin  conduc-  amount o f  is calculated  and c o m p a r e d w i t h t h e amount d e t e r m i n e d by t h e w a t e r b a l a n c e , for  the e n t i r e L i l l o o e t  River  basin.  I n C h a p t e r 7, a d i s c u s s i o n is presented to i l l u s t r a t e o r d e r o f 2 km d e e p o r l e s s , tem,  i s more l i k e l y  observed  that a shallow flow rather  t o produce  i n the mountain  of the groundwater m o d e l l i n g s y s t e m on  than a deeper-seated  the t o t a l  discharge areas.  d i s c h a r g e of  the sys-  water  4  L o c a t i o n and Access The Meager M o u n t a i n v o l c a n i c north-northwest of Vancouver,  complex  B r i t i s h Columbia and a p p r o x i -  m a t e l y 60 km n o r t h w e s t o f P e m b e r t o n  ( F i g . 1 . 1 ) . Most o f t h e  mountain  complex  Lillooet  R i v e r a n d n o r t h o f Meager C r e e k  and t h e a r e a of c o n c e r n l i e s o u t h of t h e  Access t o the mountain Vancouver  or  complex  mountain recently  area.  and p r i v a t e  where  roads ( F i g .  1.2).  River valley.  The m o u n t a i n  by an e x t e n s i v e s y s t e m o f g l a c i e r s  f e e d s many o f t h e h i g h g r a d i e n t The  peaks  including  F i g u r e 1.3 i s a v i e w o f t h e Meager a n d P l i n t h  from the L i l l o o e t  capped  road  P e a k , Mount M e a g e r , Mount J o b , C a p r i c o r n M o u n t a i n a n d  P y l o n Peak. peaks  gravelled  t h e a r e a i s by l o g g i n g  M e a g e r M o u n t a i n h a s a number o f v o l c a n i c Plinth  from  logging roads continue t o  Access w i t h i n  b u i l t by B.C. H y d r o  ( F i g . 1.2).  i s by p a v e d h i g h w a y  t o 20 km n o r t h w e s t o f P e m b e r t o n  F o r e s t r y Development the  i s l o c a t e d 160 km  s t r e a m s f e e d i n g Meager C r e e k  Boundary  that  area i s  seasonally  s t r e a m s on t h e m o u n t a i n include Devastation  side.  Creek,  C r e e k , No Good C r e e k , A n g e l , Camp, Canyon a n d  C a p r i c o r n Creek. Creek a l l feed  M o s a i c Creek, A f f l i c t i o n , J o b and F a l l  into the L i l l o o e t  R i v e r o f f t h e n o r t h and e a s t  f l a n k s of the mountain. The  major h o t s p r i n g s  i n t h e a r e a s a r e t h e Meager  and P e b b l e C r e e k H o t s p r i n g s ( F i g . 1 . 4 ) . The Meager  Creek  Creek  H o t s p r i n g s a r e a p p r o x i m a t e l y 6 km f r o m t h e c o n f l u e n c e o f  5  Figure  1.2  R i v e r , g l a c i e r and m o u n t a i n peak names i n t h e Meager M o u n t a i n a r e a .  7  F i g u r e 1.3  M e a g e r and P l i n t h  peaks.  8  Meager C r e e k w i t h t h e L i l l o o e t Hotsprings  are  R i v e r , 7.5  km  l o c a t e d on  the  River.  The  Pebble  Creek  n o r t h w e s t s i d e of the  Lillooet  u p s t r e a m f r o m i t s i n t e r s e c t i o n w i t h Meager  Creek. The  two  most p r o m i s i n g  as d e t e r m i n e d by 1.4.  The  resistivity  region along  and  The  area  surveys,  the L i l l o o e t  Pebble Creek H o t s p r i n g s Reservoir.  areas f o r geothermal  has  development,  are o u t l i n e d i n F i g u r e  River  i n c l u d i n g the  been d e s i g n a t e d  the  North  n o r t h of Meager C r e e k i n c l u d i n g No  Angel Creek i s c a l l e d  the  South  Good  Reservoir.  In g e o l o g y , t h e t e r m r e s e r v o i r i n d i c a t e s t h e r e has an  accumulation  of  fluid  i n a permeable g e o l o g i c  adequate t r a p c o n d i t i o n s . to  u n i t under  Trap c o n d i t i o n s are not e s s e n t i a l  e x p l a i n the p r e s e n c e of hot  more p l a u s i b l e e x p l a n a t i o n  water  i n t h e basement r o c k .  i s that r e g i o n a l groundwater  t h r o u g h t h e more p e r m e a b l e z o n e s o r a q u i f e r s i n t h e supplying  a constant  explanation  will  f l o w of h o t  Reservoir outlined  will  be  in Fig.  Most o f t h e  water to the a r e a .  become c l e a r l a t e r  consistent with previous  i n the  r e p o r t s the  field  work d i s c u s s e d  accessibility  i t s more p r o m i s i n g ,  results.  terms North  and  a r e a s as  A  flow  rock  is  This To  be  South they  are  next s e c t i o n  has  1.2.  on  drilling  report.  u s e d , t o r e f e r t o t h e two  been c o n c e n t r a t e d and  been  the  i n the  South R e s e r v o i r  due  initial  to i t s easier geophysical  and  9  Figure  1.4  H o t s p r i n g s and r e s e r v o i r l o c a t i o n s Meager M o u n t a i n a r e a .  in  the  10  P r e v i o u s Work In  1973 t h e D e p a r t m e n t o f E n e r g y , M i n e s a n d  Canada t h r o u g h t h e G e o l o g i c a l  S u r v e y of Canada a n d t h e E a r t h  P h y s i c s B r a n c h began t o a s s e s s t h e g e o t h e r m a l tial  of western Canada.  Resources  resource poten-  The l o c a t i o n and age o f Q u a t e r n a r y  v o l c a n i c s and h i g h l e v e l p l u t o n s were c a t a l o g u e d and s t u d y was to  f o l l o w e d by a g e o c h e m i c a l  identify  higher  t h e w a t e r s most l i k e l y  temperatures at depth.  Meager M o u n t a i n for  a r e a was c h o s e n  more d e t a i l e d  investigation  this  survey of t h e r m a l  springs  t o have been a t much  As a r e s u l t  of t h i s work t h e  a s t h e most f a v o u r a b l e r e g i o n ( L e w i s and S o u t h e r ,  1978).  S i n c e 1973 v a r i o u s s u r v e y s i n t h e Meager M o u n t a i n have been c o n d u c t e d  by t h e G e o l o g i c a l S u r v e y  area  o f Canada a n d  the  E a r t h P h y s i c s Branch of Energy  M i n e s and R e s o u r c e s  and  by N e v i n , S a d l i e r - B r o w n , G o o d b r a n d e L t d . , a n d t h e i r  contractors  f o r the B r i t i s h Columbia  Authority.  Much o f t h e e a r l y work  d i e s such as r e s i s t i v i t y , totelluric and  surveys.  sub-  H y d r o a n d Power  involved geophysical stu-  self-potential,  s e i s m i c and magne-  E x t e n s i v e g e o l o g i c mapping of t h e r e g i o n  g e o c h e m i s t r y o f t h e t h e r m a l a n d c o l d w a t e r s h a s been com-  pleted.  I n r e c e n t y e a r s a g r e a t e r amount o f d r i l l i n g  been u n d e r t a k e n tial  Canada  i n t h e p r o m i s i n g a r e a s d e l i n e a t e d by t h e  g e o p h y s i c a l work.  illustrated  The l o c a t i o n  of t h e s e d r i l l  ini-  holes i s  i n F i g u r e 1.5.  The f o l l o w i n g two l i s t s ,  has  summary o f work c o m p l e t e d  i s divided  one f o r e a c h o f t h e two main p a r t i c i p a n t s  into  i n the  11  Glacier  DRILL HOLES  1. E M R - 1 2. E M R - 2 Logging Road 3. M1 - 7 4 D 4. M2-75D Drill Hole 5. M 3 - 7 5 D 6. M 4 - 7 5 D 7. L1 - 7 8 D 8. M 5 - 7 8 D F i g u r e 1.5 D r i l l h o l e l o c a t i o n s i n t h e Meager Mountain area.  9. M 6 - 7 9 D 10. M 7 - 7 9 D 11. M 8 - 7 9 D 12. M 9 - 8 0 D 13. M 1 0 - 8 0 D 14. M11 - 8 0 D 15. M 1 2 - 8 0 D 16. L 2 - 8 0 D 17. L 3 - 8 0 D  12  project. al.  B.C. 1974  A p o r t i o n of t h i s  summary i s t a k e n  from F a i r b a n k  et  (1979).  H y d r o and  Power A u t h o r i t y  G e o l o g i c a l , g e o c h e m i c a l and  geophysical  surveys  were  initiated. 1975  Dipole-dipole resistivity and  water geochemistry  south  surveys,  diamond  drilling  s t u d i e s were p e r f o r m e d on  s i d e of the mountain area  the  i n t h e Meager C r e e k  valley.  T h i s work d e f i n e d t h e S o u t h R e s e r v o i r a s  a  tabular  s h a p e d body open t o t h e n o r t h u n d e r Meager  Mountain. 1976  A s e l f - p o t e n t i a l ( S P ) geophysical s i d e of t h e m o u n t a i n was  1977  A resistivity  low  of t h e L i l l o o e t pole 1978  was  Pole-pole  in  work on  t h e n o r t h and  Reservoir area. one  i n the North  the South R e s e r v o i r  .  Two  River approximately  mostly  n o r t h of  was  undertaken  exploratory  near the  holes one  in holes  Lillooet  i t s confluence  mapping was  i n the South R e s e r v o i r a r e a .  side  reservoir re-  Twelve p e r c u s s i o n d r i l l  1 km  Geologic  south  R e s e r v o i r and  were sunk a l o n g Meager C r e e k and  Meager C r e e k .  confluence  Pebble Creek using a p o l e -  A minor d i p o l e - d i p o l e survey  were d r i l l e d ,  north  survey.  resistivity  the N o r t h  the  d e l i n e a t e d near the  of t h e m o u n t a i n f u r t h e r d e l i n e a t e d t h e gimes.  on  inconclusive.  R i v e r and  resistivity  survey  with  accomplished, Radon gas  and  13  mercury  s u r v e y s were u n d e r t a k e n  i n an a t t e m p t t o de-  l i n e a t e geothermal water pathways t o the s u r f a c e . 1979  The d i p o l e - d i p o l e  resistivity  the North R e s e r v o i r a r e a . were d r i l l e d  Three e x p l o r a t i o n h o l e s  i n the South R e s e r v o i r .  G e o l o g i c map-  p i n g o f t h e S o u t h R e s e r v o i r a r e a was c o n t i n u e d .  A  r e c o n n a i s s a n c e s t u d y of basement-rock  was  initiated  to determine  alteration  p a t t e r n a s s o c i a t e d with the i n f e r r e d  South R e s e r v o i r  zone i n e i t h e r  (Fairbank et a l . ,  F i v e e x p l o r a t i o n h o l e s were d r i l l e d Reservoir.  alteration  i f there i s a hydrothermal  north-south s t r u c t u r a l  1980  s u r v e y was c o n t i n u e d i n  the N o r t h or  1980). i n the South  G e o l o g i c m a p p i n g was c o n t i n u e d i n t h e  N o r t h and S o u t h R e s e r v o i r a r e a s .  A fracture  of t h e basement g r a n d i o r i t e s was u n d e r t a k e n South  Two  i n the  Reservoir.  Energy Mines & Resources 1973  survey  Canada  50 m d i a m o n d d r i l l  h o l e s were b o r e d a t t h e Meager  Creek H o t s p r i n g s . 1974  Microseismicity  s t u d i e s were c o m p l e t e d  i n t h e Meager  Mountain area. 1976  Seismic p r o f i l i n g  was u n d e r t a k e n  Valley, magnetotelluric  i n the upper  Lillooet  s u r v e y s were e x e c u t e d between  Meager C r e e k and P e m b e r t o n Meadows i n t h e L i l l o o e t Valley.  Diamond d r i l l i n g  g r a d i e n t s were u n d e r t a k e n  and s t u d i e s o f t e m p e r a t u r e i n the L i l l o o e t  and  14  S q u a m i s h v a l l e y s by L e w i s Branch.  (1977)  A w a t e r g e o c h e m i s t r y s t u d y of P e b b l e  Meager C r e e k H o t s p r i n g s and by Hammerstrom and Brown  and  s u r f a c e w a t e r s was  (1977)  done  a t the Department of  Geological Sceinces, University and  of the E a r t h P h y s i c s  of B r i t i s h  Columbia  f o u n d no e v i d e n c e t h a t t h e w a t e r had been  heated  a b o v e 80°C. 1977  D e t a i l e d g e o l o g i c a l and Meager M o u n t a i n Read  (1977)  volcanic  mapping of  c o m p l e x was  initiated  the by  f o r the G e o l o g i c a l Survey of Canada.  M i c h e l and F r i t z  (1977)  of the U n i v e r s i t y  of  W a t e r l o o , Department of E a r t h S c i e n c e performed  an  i s o t o p e s t u d y o f s t r e a m w a t e r , s p r i n g w a t e r and  snow  samples  i n t h e Meager M o u n t a i n  origin,  history,  discharging 1978  stratigraphic  f l o w and c h e m i s t r y o f t h e  of  the  natural  groundwater.  Read c o n t i n u e d t o map Souther  area to i n t e r p r e t  (1978)  the v o l c a n i c complex.  r e l e a s e d a summary and  Lewis  interpretation  t h e i n f o r m a t i o n o b t a i n e d a t Meager M o u n t a i n  date w i t h respect ot i t s geothermal  and  to  resource poten-  tial. 1979  Read  (1979)  c o n t i n u e d m a p p i n g and  cal  map  of t h e Meager M o u n t a i n  the  University  undertook  an  released a  area.  of W a t e r l o o , D e p t .  isotope hydrogeology  Clark  geologi(1980)  of E a r t h S c i e n c e s , and  geothermometry  s t u d y o f t h e t h e r m a l w a t e r s a t Meager M o u n t a i n f o u n d no e v i d e n c e t h a t  of  t h e w a t e r s were h e a t e d  and above  140°C. W i t h t h e f a m i l a r i z i n g i n t r o d u c t o r y m a t e r i a l a t hand, t h e physical scribed  s e t t i n g o f t h e Meager M o u n t a i n a r e a c a n now in detail.  be d e -  16  C h a p t e r 2. PHYSICAL SETTING I n an a t t e m p t t o i n t e r p r e t t h e h y d r o g e o l o g y o f an a r e a one must f i r s t which t h e water water  i s flowing  i s discharging  sential are  h a v e an u n d e r s t a n d i n g o f t h e m a t e r i a l  that  a n d o f t h e l o c a t i o n s where t h e  from t h e m a t e r i a l .  Mountain  I t i s therefore es-  t h e g e o l o g y o f an a r e a a n d t h e s p r i n g  known, i f r e a s o n a b l e h y d r o g e o l o g i c a l  t o be made.  through  This chapter discusses  a r e a and t h e p h y s i c a l  locations  interpretations are  t h e g e o l o g y o f t h e Meager  s e t t i n g of t h e h o t and c o l d  springs.  Regional Meager M o u n t a i n the  axis  ding  i s situated  of the Coast P l u t o n i c  The n o r t h w e s t e r l y  Tertiary  Coast P l u t o n i c  Creek  and the G a r i b a l d i  B e l t of  Complex a t t h e S a l a l P l u t o n  within  n e a r Meager  Potassium-argon  t h e p l u t o n s of t h e Pemberton B e l t  range  The v o l c a n o e s o f t h e G a r i b a l d i  Belt  much y o u n g e r , g i v i n g p o t a s s i u m - a r g o n a g e s o f 4 Ma t o l e s s  t h a n 100,000 y e a r s . sist  tren-  Pemberton B e l t of l a t e  Quaternary volcanoes, i n t e r s e c t  f r o m 7.9 t o 18 Ma o l d .  near  and metamorphic  ( F i g . 2.1) (.Lewis a n d S o u t h e r , 1978) .  dates suggest that  are  granitic  trending  and Q u a t e r n a r y p l u t o n s ,  north-south trending  i n the Coast Mountains  Complex, a n o r t h w e s t e r l y  b e l t o f T e r t i a r y and o l d e r  rocks.  the  Geology  of s u b v o l c a n i c  The P e m b e r t o n B e l t roots  i s believed  of a Miocene v o l c a n i c  t o con-  front  related  17  Figure  2.1  R e g i o n a l g e o l o g y and t h e l o c a t i o n o f thermal springs i n southwestern B r i t i s h C o l u m b i a ( a f t e r L e w i s a n d S o u t h e r , 1978)  18  to the  subduction  Souther,1978). Garibaldi  of  The  t h e J u a n de  Fuca P l a t e  six andesite-dacite  B e l t are a l s o considered  d u c t i o n , and  are  b e l i e v e d t o be  Cascades i n the western U n i t e d B a k e r , Mount S t . H e l e n s , and  an  (Lewis  and  v o l c a n o e s of  t o be  the  r e l a t e d to t h i s  extension  of the  sub-  High  S t a t e s , w h i c h i n c l u d e Mount  other  volcanic  centres  (Clark,1980). I n t h e Meager M o u n t a i n a r e a c o n s i s t s of n o r t h w e s t t r e n d i n g v o l c a n i c s and  a l l o v e r l a i n by  volcanic  rocks.  cuts  o l d e r p l u t o n i c and  of  the  pluton The  Lillooet  level  The  Salal  River.  Creek P l u t o n  isolated  Some s m a l l e r north  i s part  of  of  meta-  diorites  p a t c h e s of  metamorphic r o c k s  younger  monzonite,  near the  satellite  and  head  b o d i e s of  the  p o r t i o n o f Meager M o u n t a i n . the  P e m b e r t o n B e l t of  high  plutons.  Local The  University  Geological  of B r i t i s h C o l u m b i a .  S u r v e y of  in greater  and  originally  t h e s i s at  the  More r e c e n t l y Read detail  (1977,  under c o n t r a c t  to  the  Canada.  o l d e r p o r t i o n of  pread andesite  Complex was  (1975) f o r a B.Sc.  mapped t h e a r e a  The  Geology  Meager M o u n t a i n V o l c a n i c  mapped by A n d e r s o n  1979)  strips  Creek P l u t o n , a q u a r t z  u n d e r l i e p a r t of t h e  Salal  discontinuous  P l u t o n i c complex  m e t a s e d i m e n t s s u r r o u n d e d by q u a r t z  g r a n o d i o r i t e s and  the  the C o a s t a l  i s best  the complex c o m p r i s e s mainly exposed i n the  south.  The  widesyounger  19  north half lying  i s composed o f d a c i t e f l o w s a n d l a v a domes  the older andesite Read  (1979) s u b d i v i d e d blages,  flows.  (1979) i n i t i a l l y  canic assemblages.  four  over-  b r o k e t h e complex  W i t h f u r t h e r mapping t h e complex  into nine  vol-  a n d age d a t i n g Read  f u r t h e r i n t o 18 v o l c a n i c assem-  i n t h e P l i o c e n e a n d 14 i n Q u a t e r n a r y  time.  L e w i s a n d S o u t h e r (1978) g r o u p e d t h e a s s e m b l a g e s o f Read (1977) i n t o  f o u r main u n i t s o r p h a s e s w h i c h w i l l  be d i s c u s s e d  below. The cia  bottom of the v o l c a n i c p i l e c o n s i s t s of b a s a l  w h i c h h a s i n c o r p o r a t e d b l o c k s o f basement i n a t u f f a c e o u s  matrix, exceeding of t h e c o m p l e x  300 m i n t h i c k n e s s a l o n g  (Read,1977).  This  local  basement r o c k .  sequence tuff.  the southern  side  indicates that the i n i t i a l  e r u p t i o n was e x p l o s i v e , l e a d i n g t o e x t e n s i v e  (Fig.  brec-  fracturing  of t h e  D i r e c t l y o v e r l y i n g the b r e c c i a i s a  c o n s i s t i n g o f d a c i t e f l o w s and up t o 500 m o f a c i d  The b r e c c i a , f l o w s a n d t u f f  are a l l part of u n i t 1  2.2). The  p o r p h y r i t i c a n d e s i t e s and minor h y p a b y s s a l  intru-  s i o n s o f u n i t 2 make up t h e m a i n mass o f t h e c o m p l e x . P o t a s s i u m - a r g o n d a t e s r e p o r t e d by L e w i s a n d S o u t h e r r a n g e f r o m 4.2 ± 0.3 Ma t o 2.1 ± 0.2 Ma s u g g e s t i n g  (1978) a long  period of i n t e r m i t t e n t a n d e s i t i c volcanism. The  y o u n g e s t r o c k s o f t h e c o m p l e x , u n i t 3, a r e d a c i t e  f l o w s , b r e c c i a s , t u f f s and h y p a b y s s a l  intrusives.  The u n i t  20  F i g u r e 2.2.  Geology o f t h e Meager M o u n t a i n a r e a L e w i s a n d S o u t h e r , 1979) .  (after  21  is  up t o 600 m t h i c k .  The M e a g e r , C a p r i c o r n , J o b a n d P l i n t h  summits a l o n g w i t h a l a r g e p o r t i o n of t h e c e n t r a l and n o r t h e a s t p a r t of t h e complex a r e comprised The occurred  most r e c e n t v o l c a n i c a c t i v i t y  a t Meager M o u n t a i n  2440 ± 140 y e a r s ago w i t h t h e d i s c h a r g e o f t h e  B r i d g e R i v e r a s h (Nasmith as  o f u n i t 3.  e t a l . , 1967) w h i c h c o v e r e d  f a r e a s t a s B a n f f .Park, A l b e r t a .  Deposits  an a r e a  of t h e a s h near  t h e m o u n t a i n a r e up t o 30 m t h i c k a n d c o n s t i t u t e t h e y o u n g e s t p o r t i o n of the B r i d g e R i v e r The  unit.  Meager C r e e k and L i l l o o e t  Meager M o u n t a i n  , h a v e been f i l l e d  of u n c o n s o l i d a t e d g l a c i a l  gravels with interbedded  In L i l l o o e t  valley  slopes.  till  layers.  The  drill  to the r i v e r  interbedded  at d r i l l  The  Outwash sands and  zones of l a r g e b o u l d e r s  and r a r e  l a y e r s were e n c o u n t e r e d .  thin  F a r t h e r down  h o l e EMR73-1 a n d EMR73-2 t h e o v e r b u r d e n t h i n s  18 m o r l e s s , p a r t l y  narrowing  to  axis.  t o i n t e r s e c t e d bedrock.  glaciolacustrine clay stream  and  h o l e M5-78D i n t h e Meager C r e e k v a l l e y was sunk  250m a n d f a i l e d gravels,  fill  The u n c o n s o l i d a t e d d e p o s i t s a r e t h o u g h t  be much d e e p e r c l o s e r Drill  drill  47 m o f o u t w a s h s a n d s a n d  i s s i t u a t e d near t h e c o n t a c t between t h e v a l l e y  the rock  to  bouldery  surrounding  with varying thicknesses  deposits.  h o l e L1-78D ( F i g . 1.4) e n c o u n t e r e d  hole  valleys,  because of a bedrock h i g h and v a l l e y  i n the area. granitic  basement i n t h e Meager M o u n t a i n a r e a i s  22  highly  j o i n t e d and f r a c t u r e d b e c a u s e o f t h e e x p l o s i v e  of t h e i n i t i a l  Meager M o u n t a i n e r u p t i o n s .  r e v e a l e d t h a t t h e r e a r e 2 dominant j o i n t d i n a t e s e t s i n the South R e s e r v o i r a r e a . fracture The sive  survey  will  f o l l o w i n Chapter  A fracture  survey  s e t s a n d two  subor-  More d e t a i l s o f t h e  5.  v o l c a n i c rocks are a l s o h i g h l y j o i n t e d .  fracture  survey  nature  An  exten-  was n o t c a r r i e d o u t i n t h e v o l c a n i c s b u t  s t e e p l y d i p p i n g s e t s appear t o dominate. The  g r o u n d w a t e r movement  rocks w i l l  be m a i n l y  along  i n t h e basement a n d v o l c a n i c  the f r a c t u r e s i n the rock.  amount o f w a t e r t h a t moves t h r o u g h rock m a t r i x canic  s h o u l d be e s s e n t i a l l y  the r e l a t i v e l y negligible.  The  impermeable  In the v o l -  r o c k s t h e f r a c t u r e p a t t e r n s a r e t h e r e f o r e much more  important vement. Chapter7,  than  the l i t h o l o g y  In the hydrogeologic  w i t h respect t o groundwater  mo-  m o d e l l i n g which i s d e s c r i b e d i n  t h e v o l c a n i c s a r e lumped i n t o one  hydrogeologic  unit. Before  d e s c r i b i n g the physiography  s p r i n g s a t Meager M o u n t a i n , a b r i e f physiography  of the area  of t h e hot and c o l d  d e s c r i p t i o n of the b a s i c  i s i n order.  23  Physiography The  impressive  surpassed  o n l y by  The  relief  geology  i t s spectacular  The  f r o m 425  2000 m i n l e s s t h a n  The  R i v e r v a l l e y and  i n e l e v a t i o n f r o m 425 upper r e a c h e s . Creek v a l l e y including  5 km  2.3  to  steep  s l o p e s and  weathering,  leads to very illustrates  along  The  Job  their  Meager peaks  range  be-  1.3.  r e s i s t a n c e of the v o l c a n i c s i n the  r a p i d e r o s i o n of t h e v o l c a n i c p i l e .  one  m in  r u g g e d n e s s o f Meager  in Figure  low  range  of t h e many d e e p l y  area,  Figure  2.4  i n c i s e d v a l l e y s and  at a rate too r a p i d f o r vegetation  to  hold. The  (Fig.  mountain  1.2)  streams. the  the  sea  mountain  w i t h the h i g h p r e c i p i t a t i o n  canyons d i s i n t e g r a t i n g take  The  P y l o n , M e a g e r , C a p r i c o r n and  P l i n t h peaks i s i l l u s t r a t e d The  t o 900  d e p i c t s a p o r t i o n of the  i n the South R e s e r v o i r area.  Plinth,  with  horizontal distance.  confluence  tween 2450 t o 2700 m i n e l e v a t i o n . and  2700 m a b o v e  t h e Meager C r e e k v a l l e y  m at t h e i r  Figure  2300 m  rugged w i t h e l e v a t i o n changes  of more t h a n Lillooet  i s more t h a n  m t o over  topography i s very  is  physiography.  a t Meager M o u n t a i n  the e l e v a t i o n r a n g i n g level.  of t h e Meager M o u n t a i n a r e a  i s c a p p e d by an  that terminates  extensive glacier  a t t h e h e a d w a t e r s o f a'number of  Many of t h e g l a c i e r s h a v e a q u i r e d t h e  streams to which they  Affliction,  Devastation,  system  supply J o b and  meltwaters, Capricorn  same name a s  s u c h as glaciers.  Mosaic,  24  F i g u r e 2.4  Rapid e r o s i o n of the v o l c a n i c  rock.  25  The tremely  gradient  o f t h e s t r e a m s on Meager M o u n t a i n  high at approximately  and d e e p , in t h e i r  steep-sided young  ( F i g u r e 1.4)  0.3  The  high  v a l l e y s are c h a r a c t e r i s t i c  s t a g e of development.  from D e v a s t a t i o n  Manatee Creek,  t o 0.4.  is a radial  The  i s ex-  of  gradient streams  stream p a t t e r n  Creek counter  pattern, typical  clockwise  to  of a v o l c a n i c  mountain. Fir, forest  hemlock  b e l o w 1500  tree l i n e , their  and c e d a r t r e e s d o m i n a t e t o 1800 m.  i n a r e a s were e r o s i o n  i s slow enough t o a l l o w f o r  development.  The divided  Springs  hot s p r i n g s of s o u t h w e s t e r n B r i t i s h Columbia can i n t o two g r o u p s .  the Pemberton  Belt  The  ( F i g . 2.1)  first and  group i s a s s o c i a t e d  fault  system of the Pemberton  p e r m e a b i l i t y needed teoric  to allow  I t appears that  f o r the deep c i r c u l a t i o n  ( F i g . 2.1). research  two h o t s p r i n g a r e a s o f i n t e r e s t  are the Pebble Creek h o t s p r i n g s  Creek h o t s p r i n g s  of  me-  with  i n t h e Meager M o u n t a i n and Mount  The  the  heating.  second group of hot s p r i n g s a r e a s s o c i a t e d  Quaternary volcanism  with  B e l t has s u p p l i e d t h e f r a c t u r e  w a t e r s and t h e i r c o n s e q u e n t  The  be  i n c l u d e s w e l l known h o t  s p r i n g s s u c h as H a r r i s o n and S l o q u e t .  this  subalpine  A l p i n e meadows e x i s t a b o v e t h e  Thermal  areas  the  l o c a t e d a t Meager M o u n t a i n  Cayley to  and Meager  ( F i g . 1.2,  2.2).  26  Meager C r e e k h o t s p r i n g s  issue  from c o a r s e f l u v i a l  sand  and g r a v e l d e p o s i t s a p p r o x i m a t e l y 6 km f r o m t h e c o n f l u e n c e o f Meager C r e e k w i t h t h e L i l l o o e t and s e e p s  River.  More t h a n 30 s p r i n g s  i s s u e f r o m a 1200 s q u a r e m e t e r a r e a ( F i g . 2.5) w i t h  a total  d i s c h a r g e o f a p p r o x i m a t e l y 40 1/s, a t t e m p e r a t u r e s o f  45-55°C  ( L e w i s and S o u t h e r , 1 9 7 8 ) .  It  i s b e l i e v e d that the l o c a t i o n of the h o t s p r i n g s i s  c o n t r o l l e d by an u n d e r l y i n g b e d r o c k t o p o g r a p h i c h i g h . F i g u r e 1.4 t h e o u t l i n e o f t h e S o u t h R e s e r v o i r e x t e n d i n g down t h e Meager C r e e k v a l l e y Hotsprings.  Thermal  In  shows a t o n g u e  t o t h e Meager  Creek  waters probably enter the v a l l e y  fill,  t r a v e l down g r a d i e n t a n d e x i t s a t t h e p r e s e n t h o t s p r i n g s site.  The r i s e  valley  fill,  at  i n the bedrock causes a t h i n n i n g of the  which i n t u r n , gives r i s e  the present p o s i t i o n  o f t h e Meager C r e e k  One k i l o m e t e r u p s t r e a m the  t o hot water  Hotsprings.  f r o m Meager C r e e k H o t s p r i n g s i s  Placid Hotsprings, discharging  f r o m a g r a v e l bank o f  Meager C r e e k a t an e s t i m a t e d r a t e o f 2 1/s a t 45°C. kilometers  farther  upstream  s u i n g 20-40°C w a t e r  surfacing  Five  i s t h e No Good Warm S p r i n g s i s -  f r o m a g r a s s y sandy bank on t h e n o r t h  s i d e o f Meager C r e e k a t a r a t e o f 5 1/s.  The warm  springs  represent  t h e most w e s t e r l y d i s c h a r g e o f t h e r m a l w a t e r s f o u n d  at  Creek.  Meager  The P e b b l e C r e e k H o t s p r i n g s a r e l o c a t e d on t h e n o r t h e a s t s i d e of t h e L i l l o o e t  River,  l u e n c e w i t h Meager C r e e k .  7.5 km u p s t r e a m  from i t s c o n f -  The two main v e n t s o c c u r on, a 20 m  27  MEAGER  0  20  THERMAL  40  SINTER  mirrti  F i g u r e 2.5  CREEK  HOT  DISCHARGE  LINED POOL  OlAMONO DRILL HOLE  L o c a t i o n o f m a j o r v e n t s a t t h e Meager C r e e k h o t s p r i n g s s i t e ( a f t e r C l a r k , 1980).  PEBBLE / f'v;  CREEK  HOT  THERMAL  OlS  SINTER  SPRINGS  DEPOS  MAINWENT  r  rmTi7T LILLOOET 20  40  mttrit  F i g u r e 2.6  SPRINGS  L o c a t i o n o f major v e n t s a t t h e P e b b l e Creek h o t s p r i n g s s i t e ( a f t e r C l a r k , 1980).  28  h i g h b e n c h , s i t u a t e d on The  thermal  in  the area  t h e bank o f t h e  waters deposit c a l c i t e of the v e n t s .  tufa,  debris outcropping  ( F i g . 2.6).  s t a i n e d deep ochre  A d d i t i o n a l seeps i s s u e from  q u a r t z monzonite bedrock, unconsolidated lastic  river  on  the  d e p o s i t s and  the pyroc-  f a c e of t h e b e n c h n e a r  the  river. The  Pebble Creek H o t s p r i n g s  issue d i r e c t l y  u n l i k e t h e Meager C r e e k H o t s p r i n g s  from  which i s s u e from  bedrock, valley  fill.  Cold  Springs  A number of c o l d s p r i n g s e x i s t complex, ranging 2.7  shows t h e  to date. canic  The  location  found  the  o r c l a y and  s t r a t i g r a p h y of t h e  coarse  a l l u v i u m e x p o s e d on  t h e c o n t a c t and  discovered vol-  m a t e r i a l are deposits.  The  between  the s t e e p  water t r a v e l l i n g  m e a b l e a l l u v i u m i n t e r s e c t s t h e c l a y l a y e r and i t . The  Figure  seeps are u s u a l l y found at c o n t a c t s  of V-shaped stream v a l l e y s .  trate  m.  i n t h e basement r o c k ,  s i t e s of s p r i n g s i n t h e u n c o n s o l i d a t e d  s p r i n g s and  silt  m t o 1850  the u n c o n s o l i d a t e d m a t e r i a l .  g e n e r a l l y c o n t r o l l e d by The  f r o m 580  of t h e m a j o r c o l d s p r i n g s  springs are  r o c k and The  in a l t i t u d e  i n t h e Meager M o u n t a i n  sides  i n the  per-  cannot pene-  water i s , t h e r e f o r e , f o r c e d to t r a v e l  along  i s s u e as a s p r i n g . c  A number of c o l d s p r i n g s a t h i g h e l e v a t i o n s d i s c o v e r e d  COLD SPRINGS Glacier Logging Road  1. Devastation 2. Boundary 3. CaC0 4. Moria 5. Rivendell 6. Angel Cirque 7. Problem 3  •  Figure  Cold Spring  2.7  Location of the cold Mountain area.  springs  8. Logger 9. Fall Creek 10. 78-H-1 11. Job 12. Job West 13. Affliction 14. Mt. Athelstan i n t h e Meager  30  by  Read  ( 1 9 7 9 ) and  controlled.  The  Clark  (1980) a r e  springs discharge  also  stratigraphically  at geologic  contacts  tween v o l c a n i c l a y e r s , v o l c a n i c - b a s e m e n t c o n t a c t s volcanic-unconsolidatedThe  author,  during  deposit  Figure  had  2 t o 25  be  discharge discussed  r a t e s of  i n C h a p t e r 6,  2.7.  The  1/s.  springs  o b s e r v e a l l 14 investigated  C a l c u l a t i o n s , that  show t h a t t h e c o l d s p r i n g s  b u t e a maximum of o n l y  2 to 3 percent  ter  i n t h e Meager C r e e k B a s i n .  discharge  observed  of g r o u n d w a t e r r e l e a s e d t h o u g h t t o be It of  should  and  be  exist  in local,  In the  of t h e  the  area  can  be  information  be  system i n the i n the  considered  hydrogeologic  examined. of  groundwaThe  amount  is therefore,  low-elevation  discussed.  the  Before  3.  regional  It will  aspects  shown  dis-  The areas.  been d i s c u s s e d ,  the  of the Meager M o u n t a i n  t h i s examination, of  be  e l e v a t i o n s and  low-lying discharge  basic physics  i n Chapter  a r e a s near  low-lying areas.  t h a t t h e p h y s i c a l s e t t i n g has and  contri-  t h e c o l d s p r i n g s and a l l  system at higher  springs n a t u r a l l y occur  hydrologic  total  following chapter,  systems w i l l  that water enters  Now  the c o l d s p r i n g s  n o t e d t h a t most o f  streams.  groundwater flow  c h a r g e s out  of t h e  will  insignificant.  the h o t s p r i n g s  creeks  by  and  boundaries.  h i s f i e l d w o r k , d i d not  c o l d s p r i n g s marked on  be-  background  groundwater flow w i l l  be  31  C h a p t e r 3. FUNDAMENTALS OF GROUNDWATER FLOW This chapter flow  discusses  t h e b a s i c p h y s i c s of groundwater  i n an a t t e m p t t o g e n e r a t e an u n d e r s t a n d i n g  logic  environments across  the interdisciplinary  t h e Meager M o u n t a i n g e o t h e r m a l p r o j e c t . drogeological 4.  of hydrogeoboundaries of  Readers w i t h a hy-  b a c k g r o u n d may want t o move d i r e c t l y  The m a j o r i t y o f t h e m a t e r i a l i n t h i s c h a p t e r  from Freeze and Cherry wish  (1979).  t o Chapter  was t a k e n  The i n t e r e s t e d r e a d e r may  t o r e f e r t o t h i s t e x t i f more d e t a i l  i s desired.  D a r c y ' s Law The  science  of groundwater hydrology  began i n 1856 when  H e n r y D a r c y p u b l i s h e d a r e p o r t on h i s l a b o r a t o r y a n a l y z i n g t h e flow of water through sands. ment was s e t up a s i n F i g u r e cross and  section A i sf i l l e d  manometers. the  t o f l o w t h r o u g h t h e sand  t o the outflow  l e v e l s a r e h^ a n d h  a r b i t r a r y datum s e t a t z=0. ter  intakes i sM .  denoted Let  a t each end,  tubes and a p a i r of  rate.  t i o n s o f t h e manometer i n t a k e s a r e z-^ a n d z t i o n s of the f l u i d  c y l i n d e r of  w i t h sand, stoppered  Water i s a l l o w e d  i n f l o w rate Q i sequal  Darcy's e x p e r i -  3.1. A c i r c u l a r  equipped with inflow and outflow  experiment  2  2  until  The e l e v a -  and t h e e l e v a -  with respect  t o an  The d i s t a n c e b e t w e e n t h e manome-  The d i f f e r e n c e i n f l u i d  levels  h-^l^is  asAh. us d e f i n e v, t h e s p e c i f i c d i s c h a r g e  through the c y -  F i g u r e 3.1  Experimental apparatus f o r the i l l u s t r a t i o n of Darcy's law ( a f t e r Freeze and Cherry, 1979) .  F i g u r e 3.2  H y d r a u l i c head h, pressure head V, and e l e v a t i o n head z f o r a l a b o r a t o r y manometer ( a f t e r Freeze and Cherry, 1979) .  33  Under,  as v= |  (3.1)  where v has t h e d i m e n s i o n s o f are  [ L / T ] and 3  be m/s. better  [L/T] i f the d i m e n s i o n s of Q  t h o s e o f A a r e [ L ] . The  SI u n i t s f o r v  2  A l t h o u g h v has t h e d i m e n s i o n s of v e l o c i t y i t i s thought of as a f l u x  rate  [L /T/L ]. 3  2  D a r c y ' s e x p e r i m e n t showed t h a t v i s d i r e c t l y tional  would  t o Ah  and  inversely proportional  to A l .  propor-  Darcy's  law  i n one d i m e n s i o n c a n t h e n be w r i t t e n a s , v=-KA|  or,  in differential  (3.2)  form,  V=-K|J  (3.3)  where K i s a c o n s t a n t o f p r o p o r t i o n a l i t y . I n e q u a t i o n 3.3,  K i s known a s t h e h y d r a u l i c  t y , h i s c a l l e d t h e h y d r a u l i c h e a d , and gradient.  ^  Below i s a d e t a i l e d e x p l a n a t i o n  conductivi-  i s the  hydraulic  o f t h e s e parame-  ters. F r e e z e and C h e r r y  (1979), q u o t i n g Hubbert(1940),  a p o t e n t i a l a s "a p h y s i c a l q u a n t i t y , at every point that  i n a flow  of  c a p a b l e o f measurement  s y s t e m , whose p r o p e r t i e s a r e  flow always o c c u r s from r e g i o n s i n which the  has h i g h e r v a l u e s t o t h o s e i n which the d i r e c t i o n i n space."  such  quantity  i t has l o w e r ,  regardless  They n o t e t h a t a p o t e n t i a l  s h o u l d have d i m e n s i o n s o f e n e r g y p e r u n i t mass. use of e l e m e n t a r y p h y s i c s ,  define  Hubbert  illustrated  Through the that  the  fluid  34  potential  $  f o r g r o u n d w a t e r f l o w a t any  media i s s i m p l y leration  due  the h y d r a u l i c head m u l t i p l i e d  t o work w i t h .  l e n g t h and hydraulic in  the It  the h y d r a u l i c head h i s j u s t $ , and  In the  installing  hydrogeologists  field,  find i t  which i s sealed along i t s  head i s g i v e n by  t h e e l e v a t i o n of t h e w a t e r  than  piezometer. can  be  shown t h e h y d r a u l i c head has fluid  two  pressure  c y l i n d e r were s e t up v e r t i c a l l y ,  i t i n response to g r a v i t y alone.  to induce  flow the p r e s s u r e  the other  On  components, term.  fluid  If a  would  the other  ( F i g . 3.2).  a t one  end  must be  role  greater  Therefore, (3.5)  where z i s t h e e l e v a t i o n head a b o v e an a r b i t r a r y datum i s the pressure  head.  B o t h <J>  and  a r e commonly m e a s u r e d i n m e t e r s . to the  fluid  pressure  p,  z have d i m e n s i o n s The  pressure  sures .  [L]  and  by (3.6)  where P i s t h e d e n s i t y o f t h e therefore provide  and  h e a d , <r , i s  p=pg<jj  can  flow  hand,  h=z+\p  related  The  level  t h e c y l i n d e r were h o r i z o n t a l , g r a v i t y w o u l d p l a y no  and  be  a l l o w s water to enter only at a s i n g l e p o i n t .  sand-filled  if  as  t h e h y d r a u l i c head can  a piezometer  t h e e l e v a t i o n ( g r a v i t y ) t e r m and  through  acce-  (3.4)  s u i t a b l e a p o t e n t i a l as  m e a s u r e d by  the  =gh  g i s near c o n s t a n t ,  easier  by  to g r a v i t y $  Since  p o i n t i n a porous  both  fluid.  Piezometer  h y d r a u l i c h e a d s and  measurements fluid  pres-  35  The draulic  c o n s t a n t of p r o p o r t i o n a l i t y i n D a r c y ' s l a w , c o n d u c t i v i t y K,  media but  a l s o the  l a t i o n s h i p to  i s a function  fluid.  not  only  of  E x p e r i m e n t a t i o n has  the  the  hy-  porous  found the  re-  be  K=  (3.7) y  where k i s the  specific  density  fluid,  of  the  and  y i s the  lity  k or c a p a c i t y  the  The  tioned the  are  the  v o l u m e of  , the  The on  the  porosity turn  p o r o s i t y can  t i e s are  fluid.  [L ].  the  the  is  gravity, permeabi-  i s a function density  r  Hydraulic  Conductivity  o f a r o c k or  solids V , g  and  soil the  is parti-  volume  of  as (3.8)  as a p e r c e n t a g e o r a d e c i m a l an  important c o n t r o l l i n g In g e n e r a l ,  permeability  hydraulic  of  and  •  be  the  fluid.  with  the  The  The  2  to  P  k.  The  conductivity,  an  fraction. influence  increase  permeability if fluid  in in  proper-  constant.  In rock, p o r o s i t y and sity  the  c o n d u c t i v i t y K.  increases  increases  the  r  reported  hydraulic  of  porosity n i s defined v  is usually  of  u n i t volume V  n=V /V It  a c c e l e r a t i o n due  dimensions  Relationship  total  V  has  properties  i n t o the  voids  g i s the  permeability,  for transmitting a f l u i d  and  Porosity  If  intrinsic  dynamic v i s c o s i t y  medium o n l y  viscosity  or  two the  t y p e s of p o r o s i t y fracture porosity.  r e f e r s to the  porosity  of  the  exist, The  the  intergranular  intergranular  rock m a t r i x .  In a  porograni-  36  tic  rock t h i s  i s t o a l l i n t e n t s and  fracture porosity volume t h a t  r e f e r s t o t h e p e r c e n t a g e of  i s t a k e n up  f r a c t u r e p o r o s i t y may small  as  10"  the  the  l a r g e as  The the  the  unconsolidated  the  hydraulic  I f the  position  hydraulic  as of  basement r o c k s i s the  conductivity.  intergranular  K  formation,  the  the  of  major  In  the  porosity  is  I f we  s e t up  Conductivity  i s i n d e p e n d e n t of formation  posi-  i s homo-  c o n d u c t i v i t y K i s dependent  on  formation,  he-  an  xyz  the  formation  coordinate  K(x,y,z)=C, C being a  whereas i n a heterogeneous f o r m a t i o n  is  space, then i n a constant;  K(x,y,z)=C  (Freeze  and  1979).  A v a r i e t y of e n v i r o n m e n t s can s y s t e m may as  structure  fracture porosity  conductivity  hydraulic  homogeneous f o r m a t i o n ,  Cherry,  The  c o n d u c t i v i t y more t h a n  r o c k s and  deposits  within a geologic  terogeneous.  rock.  2 p e r c e n t or  H e t e r o g e n e i t y of H y d r a u l i c  tion within a geologic geneous.  total  factor.  H o m o g e n e i t y and If  hydraulic  The  porosity.  f a c t o r on  controlling  1 or  the  i n the  interconnective  Meager M o u n t a i n a r e a t h e  granular  fractures  fractured volcanic  controlling  the  the  as  influence  intergranular In  be  4  fractures w i l l the  by  to 10" .  3  purposes n e g l i g i b l e .  i n the  or b r e c c i a  be  h e t e r o g e n e o u s due  volcanics l a y e r may  cause heterogeneity.  to l a y e r i n g  o f Meager M o u n t a i n .  An  A  ( F i g . 3.3)  such  individual  flow  h a v e a homogeneous h y d r a u l i c  conductivi-  F i g u r e 3.3  Layered heterogeneity and t r e n d i n g h e t e r o g e n e i t y ( a f t e r Freeze and Cherry, 1979) .  Homogeneous, Isotropic  (x , 2  Homogeneous, Anisotropic  Z) 2  Ll —*•  H e t e r o g e n e o u s , Isotropic  Figure  3.4  H e t e r o g e n e o u s , Anisotropic  Four p o s s i b l e combinations of h e t e r o g e n e i t y and a n i s o t r o p y ( a f t e r Freeze and Cherry, 1979).  38  t y b u t when one l o o k s i s heterogeneous. c a u s e d by a f a u l t  a t t h e whole v o l c a n i c  A discontinuous  heterogeneity  o r by a l a r g e - s c a l e  can a l s o get t r e n d i n g  in a volcanic  layer  Within  heterogeneity  c a n be  a  i n flows  partially  tures  w o u l d be w i d e r a t t h e s u r f a c e a decrease  exposed a t s u r f a c e . than  in hydraulic  features formation  ( F i g . 3.3).  i n t h e Meager M o u n t a i n c o m p l e x  occur  tions causing  the system  stratigraphic  such as t h e overburden-bedrock c o n t a c t . one  pile,  Trends  could  Fracture  i n unexposed  conductivity  apersec-  with  depth.  Isotropy  and A n i s o t r o p y  A formation a t any p o i n t formation  i s isotropic  conductivity  I f one d e a l s  K  and K .  be  with  o f mea-  a n d De W i e s t ,  1966).  the three-dimensional case there  A t any p o i n t  i n an i s o t r o p i c formation  basement g r a n o d i o r i t e  t o be g r e a t e r  will  conductivity K ,  formation  K^=K^=K  z  ,  K =K =K .  a t Meager M o u n t a i n a p p e a r s t o  The two p r o m i n e n t j o i n t  d i p causing  A  of d i r e c t i o n  p r i n c i p a l d i r e c t i o n s of h y d r a u l i c  anisotropic.  vertical  conductivity K  i f , on t h e o t h e r h a n d , t h e h y d r a u l i c  ( F i g . 3.4) ( D a v i s  w h e r e a s i n an a n i s o t r o p i c The  i f i t s hydraulic  i s a f f e c t e d by t h e c h o i c e  surement a t a p o i n t  three  Conductivity  i s o f t h e same m a g n i t u d e i n a l l d i r e c t i o n s .  i s anisotropic  be  of H y d r a u l i c  the v e r t i c a l  s e t s have a n e a r  hydraulic  conductivity  K  than the h o r i z o n t a l h y d r a u l i c  conductivity  K .  z  v  39  The v o l c a n i c r o c k s , system of interbedded  on t h e o t h e r  high-permeability  l a y e r s and l o w e r - p e r m e a b i l i t y there  layer  cal  Figure  K-^ ,1*2 , . . .K^ .  heterogeneity  formation  where e a c h  with a hydraulic  conducti-  I t c a n be shown t h a t an e q u i v a l e n t  hydraulic conductivity K  z  verti-  f o r t h e s y s t e m o f l a y e r s c a n be  from t h e r e l a t i o n K =  d £ i-l  d  where n i s t h e t o t a l  i /  k  i  .  number o f l a y e r s , d i s t h e t o t a l i  ness of t h e i t h l a y e r , and K  thick-  i s the h y d r a u l i c c o n d u c t i v i t y  the i t h l a y e r . Similarly,  tal  I t c a n be shown t h a t  3.5 i s a l a y e r e d  i s homogeneous a n d i s o t r o p i c  calculated  of  flows.  b r e c c i a s and ash  i s a r e l a t i o n s h i p between such l a y e r e d  and a n i s o t r o p y .  vity  h a n d , t e n d t o be a  i t c a n be shown t h a t t h e e q u i v a l e n t  h y d r a u l i c c o n d u c t i v i t y K , f o r the layered n  horizon-  system i s  k.d.  i= 1  (3.10)  W i t h some m a t h e m a t i c a l m a n i p u l a t i o n 3.10 i t i s p o s s i b l e t o show t h a t K >K values  o f K,,K„,...K . 1 2 n  layered heterogeneity on t h e o r d e r  i t i s n o t uncommon f o r  to lead to regional anisotropy  o f 100:1 o r even  vertical  for a l l possible  In the f i e l d ,  c a n i c s a t Meager M o u n t a i n extensive  o f E q u a t i o n 3.9 a n d  greater.  the anisotropy  and near v e r t i c a l  In the l a y e r e d  values vol-  i s r e d u c e d due t o  f r a c t u r i n g that i n -  40  creases the v e r t i c a l  hydraulic  conductivity  K . z  Water T a b l e The fluid  i s d e f i n e d a s t h e s u r f a c e on w h i c h  p r e s s u r e p i n t h e p o r e s o f t h e medium i s e x a c t l y  pheric. lying head  water t a b l e  I n gauge p r e s s u r e , p w o u l d be e q u a l t o z e r o ,  f r o m E q u a t i o n 3.6  that^=0.  Since  h=i>+z,  the  the atmos-  imp-  hydraulic  a t any p o i n t on t h e w a t e r t a b l e must be e q u a l t o t h e  e l e v a t i o n z of the water t a b l e a t t h a t p o i n t . t h e w a t e r t a b l e c a n be v i e w e d a s an  Alternatively,  imaginary surface  which the pore spaces are c o m p l e t e l y s a t u r a t e d w i t h  Flow  below  water.  Nets  I f h y d r a u l i c h e a d v a l u e s a r e known t h r o u g h o u t a t w o - d i m e n s i o n a l s y s t e m , c o n t o u r s c a n be drawn j o i n i n g up p o i n t s of equal p o t e n t i a l . lines.  These c o n t o u r s a r e c a l l e d  equipotential  F l o w l i n e s c a n be c o n s t r u c t e d p e r p e n d i c u l a r t o t h e  equipotential  l i n e s which  i s the d i r e c t i o n  o f t h e maximum  potential gradient.  Flowlines  i n d i c a t e the d i r e c t i o n  w a t e r movement.  resulting  s e t o f f l o w l i n e s and  tential  lines  The  isotro-  system w i t h s a t u r a t e d , s t e a d y - s t a t e f l o w , t h r e e t y p e s of  b o u n d a r i e s can e x i s t : head  equipo-  i s known a s a f l o w n e t .  When c o n s t r u c t i n g a f l o w n e t f o r a homogeneous, pic  of  b o u n d a r i e s and  vicinity  1) i m p e r m e a b l e  b o u n d a r i e s , 2) c o n s t a n t  3) w a t e r t a b l e b o u n d a r i e s .  o f an i m p e r m e a b l e  boundary  Flow  i n the  [ F i g u r e 3 . 6 ( a ) ] must  be  41  d,  T d  K,  2  I  *-K,  Figure  3.5  R e l a t i o n s h i p between l a y e r e d h e t e r o g e n e i t y and a n i s o t r o p y F r e e z e and C h e r r y , 1979) .  Figure  3.6  Groundwater flow i n the v i c i n i t y o f (a) an i m p e r m e a b l e b o u n d a r y , (b) a c o n s t a n t h e a d b o u n d a r y , and (c) a w a t e r - t a b l e boundary ( a f t e r Freeze and C h e r r y , 19 79) .  (after  42  parallel  t o t h e b o u n d a r y b e c a u s e no f l o w c a n move a c r o s s i t .  T h i s demands t h a t  flow  lines are p a r a l l e l  e g u i p o t e n t i a l s are at right angles In t h e c a s e of a c o n s t a n t the border a t r i g h t  angles  an e q u i p o t e n t i a l l i n e As lic  discussed  [Figure  (Freeze  and C h e r r y ,  1979).  head b o u n d a r y , f l o w must meet  because the boundary i s a c t u a l l y  [Figure  3.6(b)].  p r e v i o u s l y , a t the water t a b l e the hydrau-  head h i s e q u a l  consequently  t o t h e boundary and  t o t h e e l e v a t i o n z.  n e i t h e r a flow  The w a t e r t a b l e i s  l i n e o r an e q u i p o t e n t i a l l i n e  3.6(c)],  Flow n e t s lustrated  c a n be c o n s t r u c t e d  i n Figure  f o r any o f t h e s y s t e m s i l -  3.4 a n d u s e d t o c a l c u l a t e t h e d i s c h a r g e  through the system.  For a thorough explanation  c o n s t r u c t i o n and d i s c h a r g e  of f l o w net  c a l c u l a t i o n s see F r e e z e and  Cherry  (1979) pp. 1 6 8 - 1 8 9 .  Recharge Areas, Consider  Discharge  3.7 o f  The w a t e r t a b l e c o n f i g u r a t i o n i s a s u b d u e d  ground s u r f a c e  characteristic  section Figure  The g e o l o g i c m a t e r i a l s a r e homogeneous  r e p l i c a of the topography i n t h e h i l l s the  Divides  r i d g e s a n d v a l l e y s w i t h an i m p e r m e a b l e  boundary a t t h e base. isotropic.  and Groundwater  the two-dimensional cross  a s e t of p a r a l l e l  and  Areas,  i n the v a l l e y s .  and c o i n c i d e n t  T h i s w a t e r t a b l e shape i s  o f most t o p o g r a p h y , a l t h o u g h  unaware o f any s p e c i f i c  with  the author i s  s t u d i e s of the water t a b l e c o n f i g u r a -  43  tion one  i n mountainous t e r r a i n .  h y d r a u l i c head v a l u e  of t h e d a s h e d e q u i p o t e n t i a l l i n e s  tion  of t h e w a t e r t a b l e a t  equipotential  1 ine  from the h i g h l a n d s  area  "imaginary" The  area.  the  r e g i o n ED  in Figure  In a recharge  no  area  The  a t AB  boundaries  l i n e s AB  impermeable  groundwater flow  in Figure  discharge  area  are  3.7  the net  field  modelling  3.7  teady flow  t h e n e t component o f  similar  groundthe they  recharge  saturated  the d i s c h a r g e  with time.  t o ABCD w i l l  be  the d i r e c t i o n  and  used f o r  7.  Flow  magnitude of the  Transient  In a  groundwater  f l o w t a k e s p l a c e when a t any and  area.  The  A c r o s s s e c t i o n of  purposes i n Chapter  or unsteady f l o w , t a k e s field  the  indicating  i s known as t h e  component of s a t u r a t e d  the d i r e c t i o n  are constant  known a s  thereby  Steady S t a t e Flow vs T r a n s i e n t  flow  under  the  boundaries.  i s known a s  t h e Meager M o u n t a i n a r e a ,  Steady-state  CD  f l o w e n t e r s or l e a v e s  o r CD,  the  flows  symmetry of  and  i s upward, towards the water t a b l e .  mathematical  eleva-  i s downward, away f r o m t h e w a t e r t a b l e .  r e g i o n AE  flow  these  any  1S79).  t h a t , groundwater  boundaries  I t i s obvious  ABCD t h r o u g h  Cherry,  to the  on  intersection with  towards the v a l l e y s .  r i d g e s , and  water d i v i d e s .  and  i t i s clear  system produces v e r t i c a l v a l l e y s and  i s equal  i t s p o i n t of  (Freeze  From F i g u r e 3.7,  are  The  point flow  in a  velocity  f l o w , a l s o known a s  p l a c e when a t any m a g n i t u d e of t h e  point  flow  nonsin a  velocity  Figure  3.7  G r o u n d w a t e r f l o w n e t i n a twodimensional v e r t i c a l cross-section t h r o u g h a homogeneous, i s o t r o p i c s y s t e m b o u n d e d on t h e b o t t o m by an impermeable boundary ( a f t e r Hubbert, 1940) .  0.2 S  Figure  3.8  E f f e c t o f t o p o g r a p h y on r e g i o n a l groundwater flow p a t t e r n s ( a f t e r F r e e z e and W i t h e r s p o o n , 1967) .  45  changes w i t h  time.  Flow nets sient the  flow.  c a n be drawn f o r b o t h s t e a d y - s t a t e  A flow net f o r a s t e a d y - s t a t e  system a t a l l times.  only  represents  the system  for a particular  thought of as r e p r e s e n t i n g table maintains  e n t i r e year.  In r e a l i t y ,  throughout the year system.  system  represents  A flow net f o r a t r a n s i e n t system  In r e g i o n a l groundwater  the water  and t r a n -  i n s t a n t i n time.  flow, steady-state  f l o w c a n be  the h y p o t h e t i c a l s i t u a t i o n  where  t h e same p o s i t i o n t h r o u g h o u t t h e f l u c t u a t i o n s i n the water  introduce  table  t r a n s i e n t e f f e c t s i n t o the flow  However, i f t h e c h a n g e s i n t h e w a t e r t a b l e p o s i t i o n  are  s m a l l compared w i t h  and  i f t h e r e l a t i v e c o n f i g u r a t i o n of t h e water  the  same t h r o u g h o u t t h e f l u c t u a t i o n s , we c a n r e p l a c e t h e f l u -  ctuating table  up f r o m s t o r a g e  table  s y s t e m , no w a t e r  and C h e r r y ,  i n t o t h e s y s t e m must e q u a l  Therefore, the t o t a l  The r e g i o n a l g r o u n d w a t e r  assumed t o be s t e a d y - s t a t e  flow  the t o t a l  dischage  i s taken  up  recharge  out of the sys-  i n Meager M o u n t a i n i s  f o r the purpose  i n t e r p r e t a t i o n and m a t h e m a t i c a l  1979).  i n the system i s  i n t h e medium a n d no w a t e r  i n t h e medium.  stays  system w i t h the water  f i x e d a t i t s mean p o s i t i o n ( F r e e z e  into storage  tem.  t h i c k n e s s of the system,  system with a s t e a d y - s t a t e  In a s t e a d y - s t a t e given  the t o t a l  modelling.  of  hydrogeologic  46  The  E f f e c t of the Hydrogeologic Groundwater  The  groundwater  Regime  regime i s c o n t r o l l e d  parameters which c o l l e c t i v e l y v i r o n m e n t of a g i v e n portant  geographic  region.  having  an u p l a n d  left.  Figure  while Figure  Figure  area  flow  single flow  3.8(b) i l l u s t r a t e s  systems i s o b v i o u s .  system.  isotropic  the groundwater  t o t h e r i g h t and a v a l l e y  3 . 8 ( a ) shows a f l a t  flow pattern  upland  a hilly  sections to the f a r  and water upland  table  area  with a  The d i f f e r e n c e b e t w e e n  A few s m a l l h i l l s  change a  i n t o numerous s u b s y s t e m s w i t h i n a m a j o r  Clearly,  even b a s i n s  u n d e r l a i n by homogeneous,  g e o l o g i c m a t e r i a l s c a n have c o m p l e x  groundwater  p o r o s i t y and  3.8 d e p i c t s two c r o s s  hummocky w a t e r t a b l e c o n f i g u r a t i o n . the  rock  and e v a p o t r a n s p i r a t i o n .  Minor changes i n topography can vary deal.  en-  Among t h e most i m -  relief,  conductivity, precipitation  flow a great  by a number o f  create the hydrogeologic  parameters a r e topographic  hydraulic  E n v i r o n m e n t on t h e  f l o w due t o t o p o g r a p h y a l o n e  systems of  (Freeze  and C h e r r y ,  1979).  Figure  3.9 shows t h e e f f e c t  v i r o n m e n t s on g r o u n d w a t e r Freeze  and W i t h e r s p o o n  present times tem,  of d i f f e r e n t  geologic en-  flow as m a t h e m a t i c a l l y  (1967).  Figure  s i m u l a t e d by  3 . 9 ( a ) a n d 3.9(b) r e -  an a q u i f e r a t d e p t h w i t h a c o n d u c t i v i t y 10 a n d 100  t h a t of t h e o v e r l y i n g f o r m a t i o n . flows nearly v e r t i c a l l y  horizontally  Water e n t e r s  downward t o t h e a q u i f e r ,  i n t h e a q u i f e r and f i n a l l y  the systravels  upwards i n t h e d i s -  0.2S  0  0.1 S  0.2S  0.3S  0.4S  0.5S  0.6S  0.7S  0.8S  0.9S  (e)  F i g u r e 3.9  E f f e c t of geology on r e g i o n a l groundwater flow p a t t e r n s ( a f t e r Freeze and Witherspoon, 1967) .  S  48  charge a r e a . In way  F i g u r e 3.9(c) the a q u i f e r at depth a c t s as a t h r o u g h -  f o r f l o w t o pass under An a q u i f e r  the  the o v e r l y i n g  systems.  t h a t p i n c h e s out c r e a t e s a d i s c h a r g e a r e a i n  c e n t r e of the s e c t i o n  in Figure  F i g u r e 3 . 9 ( e ) i l l u s t r a t e s how few m e t e r s  local  3.9(d). t h e d i f f e r e n c e of o n l y a  i n the p o i n t of r e c h a r g e can d e t e r m i n e  water e n t e r s a s m a l l l o c a l  whether  f l o w system or l a r g e r e g i o n a l  flow  system. It  i s clear  from t h e s e s i m p l e examples  that the  g e o l o g y o f t h e Meager M o u n t a i n  a r e a c a n have an  effect  pattern.  on t h e g r o u n d w a t e r  Other  flow  factors affecting  precipitation,  and e v a p o t r a n s p i r a t i o n w i l l  amount of w a t e r a v a i l a b l e charge zone.  the groundwater  enormous  flow such  determine  t o reach the water t a b l e  High p r e c i p i t a t i o n  w i t h low  complex  as  the  in a re-  evapotranspiration  would a l l o w a l a r g e q u a n t i t y of water t o flow t h r o u g h the u n s a t u r a t e d zone closer  t o the water  to the s u r f a c e .  cipitation  raising  Groundwater on  flow  the water  table  C o n v e r s e l y , i n an a r e a w i t h low p r e -  and h i g h e v a p o t r a n s p i r a t i o n  water t a b l e e l e v a t i o n  dependent  table,  one w o u l d  expect the  t o be l o w e r t h a n i n t h e f i r s t i s an e x t r e m e l y dynamic  case.  process very  i t s hydrogeologic environment.  T h i s review of groundwater  f u n d a m e n t a l s has been p r e -  49  sented to enable non-hydrogeologists to gain a b e t t e r t a n d i n g of t h e h y d r o g e o l o g y  of t h e Meager M o u n t a i n  it  6 and  i s presented Firstly,  ter In  regime  i n Chapters  the L i l l o o e t t h i s water  to p l a c e the  i n t o t h e c o n t e x t of t h e c o m p l e t e  River basin.  b a l a n c e and  will  complex  as  7.  however, i t i s n e c e s s a r y  t h e f o l l o w i n g c h a p t e r we  unders-  hydrologic cycle.  d e v e l o p a water  In C a p t e r  7,  groundwa-  i t will  balance for be  shown t h a t  t h e h y d r o g e o l o g i c a l model p r o v i d e a  c o n s i s t e n t p i c t u r e of the h y d r o l o g y of the a r e a .  50  Chapter  4.  PRELIMINARY WATER BALANCE Groundwater budget  or  water  water b a l a n c e take  the  of  equation  ds  -5-r-  basin  The  the  input  f o r a watershed  water  The  f o r any  simplest  period  would  out  ponents,  (4.1)  inflow  the  the  the  output  main  output  of  I into a basin change  minus o u t f l o w  i n the  storage  of  0  out  water  basin.  and  The  important  runoff  of a d r a i n a g e b a s i n .  must e q u a l  components. the  i n the  = §f  that  within  dt  component  form  states  the  important  balance  1-0 which  i s an  can  input  b r o k e n down i n t o t h e i r  parameter  parameters are  basin.  surface  be  The  major  is precipitation  and  evapotranspiration  and  runoff  has  two  prominent  water c o n t r i b u t i o n s and  the  f o r the  drainage  com-  groundwater  contributions. A water b a l a n c e is  attempted,  discharge is  being  to  the  total  estimated. in Chapter  c o n t r i b u t i o n of  runoff.  water e n t e r i n g This 6,  f o r the  As  an  the  i s useful  estimate  groundwater  Meager C r e e k  I f the  two  of  sub-basin.  manner t h e n estimates  i n the of  situation  discharge,  groundwater  system  i n two  then  is also  ways.  recharge  The  basin  groundwater  a steady-state  information  made i n a d i f f e r e n t chapter.  the  assumed, where r e c h a r g e e q u a l s  amount of  lated  to estimate  entire Lillooet  the being  Firstly,  is calcu-  c a l c u l a t i o n s are  water  groundwater  b a l a n c e of recharge  this give  51  similar  r e s u l t s t h e n i t c a n be assumed t h a t t h e y a r e r e a s o n a -  bly  correct.  ter  r e c h a r g e i s an i m p o r t a n t v a r i a b l e a s an i n p u t  in  Secondly, i n Chapter  t h e m a t h e m a t i c a l model.  recharge  influence  balance f o r the L i l l o o e t  of t h e b a s i n w i l l  first  have t o be  t i o n s t o Meager M o u n t a i n  The  examined.  Temperature stations  i n the study  e x i s t a t P e m b e r t o n Meadows, 50 km t o  4 . 1 ) . The mean d a i l y  60 km t o t h e n o r t h e a s t t e m p e r a t u r e s a n d mean t o t a l  f o r t h e s e two s i t e s a r e t a b u l a t e d  mean t o t a l  i n T a b l e 4.1.  The mean d a i l y  temperature at  P e m b e r t o n Meadows i s 7.2 "C a n d a t B r a l o r n e i s 4.3 "C. values are averaged  Organization The  pre-  p r e c i p i t a t i o n a t P e m b e r t o n Meadows i s 1024 mm  and a t B r a l o r n e i s 732 mm.  30 y e a r p e r i o d  basin  The c l o s e s t m e t e o r o l o g i c a l s t a -  s o u t h e a s t , and B r a l o r n e ,  cipitation  River  i n t h e summer o f 1 9 8 0 , t h e r e f o r e no d a t a  value i s yet a v a i l a b l e .  (Fig.  and  temperature-rainfall  a r e a were i n s t a l l e d  the  that  t e m p e r a t u r e , e v a p o t r a n s p i r a t i o n , and  Precipitation  of  narrow t h e  groundwater.  precipitation,  The  i tw i l l  of flow v a l u e s of the other v a r i a b l e s  To d e v e l o p a w a t e r  runoff  parameter  I f t h e v a l u e of t h e groundwater  i s known w i t h i n a s m a l l r a n g e ,  p o s s i b l e range  the  7, t h e amount o f g r o u n d w a -  f r o m 1941 t o 1 9 7 0 , t h e c u r r e n t  r e c o g n i z e d by t h e W o r l d  (Environment  Canada,  e l e v a t i o n of t h e v a l l e y  The  standard  Meteorological  1974). a r e a s a r o u n d Meager  Mountain  52  Figure  4.1  L o c a t i o n of data g a t h e r i n g s t a t i o n s i n the R i v e r area r e f e r r e d to i n the t e x t .  Lillooet  Table  4.1  Mean t o t a l p r e c i p i t a t i o n and mean d a i l y t e m p e r a t u r e a t Pemberton Meadows and B r a l o r n e 1941-1970  Pemberton Meadows ( E l . 300 m)  Month  Mean D a i l y " Temperature( C)  Bralorne ( E l . 1300 m)  Mean T o t a l Precipitation(mm)  Mean D a i l y Temperature( C)  Mean T o t a l Precipitation(mm)  Jan  -6.0  168  -7.8  109  Feb  -1.7  85  -3.2  60  Mar  2.6  64  -0.3  48  Apr  8.2  45  4.4  28  May  13.4  31  8.8  27  June  16.0  38  11.7  43  July  18.6  27  14.9  34  Aug  17.1  28  14.2  33  Sept  13.4  64  10.8  42  Oct  7.6  141  5.0  94  Nov  0.8  161  -1.7  98  Dec  -3.4  179  -5.7  116  7.2  1024  4.2  732  TOTAL  (From C l i m a t e o f B r i t i s h Columbia, C l i m a t i c  Normals, 1941-1970)  54  lie  a t 760 m, w h e r e a s t h o s e a t P e m b e r t o n Meadows a n d B r a l o r n e  lie  a t 300 m a n d 1300 m r e s p e c t i v e l y .  The Meager M o u n t a i n  temperature  regime i n t h e v a l l e y s p r o b a b l y  temperature  regime of these  It  h a s been f o u n d  variable  that p r e c i p i t a t i o n  of moisture  majority  The w e s t - e a s t  laden a i r from t h e P a c i f i c  variation  This  r u n o f f i s 1880 mm o v e r  dropping the The  the drainage  i n d i c a t e s t h a t a g r e a t d e a l more  a t h i g h e r e l e v a t i o n s than  point w i l l  isa  p r e c i p i t a t i o n a t P e m b e r t o n Meadows i s 1024 mm  w h i l e t h e mean a n n u a l  falls  I n g e n e r a l , t h e amount o f  o f i t s w a t e r on t h e most w e s t e r l y m o u n t a i n s .  mean t o t a l  basin.  i s extremely  drops o f f d r a m a t i c a l l y from west t o e a s t and  from h i g h e l e v a t i o n s t o l o w e r . result  between t h e  two s t a t i o n s .  i n the c o a s t a l mountains.  precipitation  lies  precipitation  i n the v a l l e y areas.  be e x p a n d e d upon i n t h e r u n o f f  This  section.  Evapotranspi rat ion No d i r e c t measurement o f e v a p o t r a n s p i r a t i o n o r tion are available Weisman  f o r t h e Meager M o u n t a i n r e g i o n .  (1967) c o l l e c t e d  and be  solar  They s t a t e t h a t p o t e n t i a l  proximately equal  Bruce and  e v a p o r a t i o n pan d a t a , o b s e r v e d  r a d i a t i o n d a t a and e s t i m a t e d Canada.  evapora-  to free-water  reservoirs, therefore their  r a d i a t i o n data  from  solar across  e v a p o t r a n s p i r a t i o n i s ap-  evaporation annual  used as e v a p o t r a n s p i r a t i o n v a l u e s .  from s m a l l  lakes  e v a p o r a t i o n values can T h e i r maps  indicate  t h a t t h e Meager M o u n t a i n a r e a h a s a maximum p o t e n t i a l  r a t e of  55  e v a p o t r a n s p i r a t i o n of approximately This value tions later  will  in this  500 mm/year.  be u s e d f o r t h e w a t e r b a l a n c e  calcula-  chapter.  Runof f The  only  River basin Pemberton  long-term  measurement o f r u n o f f  i n the L i l l o o e t  i s at the L i l l o o e t River s i t e ,  1.5 km n o r t h o f  ( F i g . 4.1) where d a i l y d i s c h a r g e  r a t e s have been  m e a s u r e d by t h e W a t e r S u r v e y o f Canada s i n c e 1 9 1 4 .  Figure  4.2 i l l u s t r a t e s a v e r a g e r u n o f f , t e m p e r a t u r e a n d p r e c i p i t a t i o n of t h e P e m b e r t o n V a l l e y .  I t i s clear,  that runoff c o r r e l a t e s  w i t h temperature and not p r e c i p i t a t i o n . l a r g e amount o f r u n o f f w h i c h r e s u l t s ice at higher that  runoff  charging  i s due t o t h e  from m e l t i n g  snow a n d  e l e v a t i o n s i n t h e warm summer m o n t h s .  i s given  in [L].  out of t h e b a s i n  of t h e b a s i n  This  Note,  The volume [ L ] o f w a t e r 3  dis-  i s m e a s u r e d a n d d i v i d e d by t h e a r e a  [ L ] to give a runoff value 2  over the drainage  basin of dimension [ L ] . As m e n t i o n e d  i n the p r e c i p i t a t i o n  annual r u n o f f of the L i l l o o e t R i v e r mm w h i l e station  the average p r e c i p i t a t i o n f r o m 1941-1970 was 1024 mm.  cipitation  at higher  section,  t h e mean  f r o m 1923-1973 was 1880 a t t h e P e m b e r t o n Meadows This  i n d i c a t e s that  e l e v a t i o n s i s much g r e a t e r  pre-  t h a n 1880  mm/year. Mean a n n u a l r u n o f f  i n t h e M i l l e r Creek b a s i n , a t r i b u -  56  J  Figure  4.2  F  M  A  M  J  J  A S O N D  Hydrometeorogical regime of the L i l l o o e t R i v e r and v a l l e y b o t t o m ( a t e r T e t i , 1979). Temperature and p r e c i p i t a t i o n were r e c o r d e d a t P e m b e r t o n Meadows (1931-1960). Discharge was r e c o r d e d a b o u t 1.5 km n o r t h o f P e m b e r t o n  (1923-1973).  57  tary of theL i l l o o e t be  just  2400 mm ± 300 mm.  n o r t h o f Pemberton i s e s t i m a t e d t o  this  i s b a s e d on summer d i s c h a r g e r e -  cords and v i s u a l  e s t i m a t e s of d i s c h a r g e d u r i n g w i n t e r low  flow  1 9 7 3 , 1974 a n d 1 9 7 5 , u n p u b l i s h e d  (Slaymaker,  Precipitation  i n t h e Meager M o u n t a i n a r e a a t h i g h e r e l e v a -  t i o n s may be 3000 mm/year o r p o s s i b l y With runoff  data).  higher.  estimates of p r e c i p i t a t i o n ,  a t hand, water b a l a n c e  e v a p o t r a n s p i r a t i o n and  c a l c u l a t i o n s c a n now be p e r -  formed .  Water  Balance  I n t h e Meager M o u n t a i n a r e a , a much more d e t a i l e d balance  equation  i s needed  than  i n order  thepreviously-mentioned  there  E q u a t i o n 4.1  t o q u a n t i f y a l l t h e h y d r o l o g i c components.  Assuming t h e s u r f a c e - w a t e r coincide,  water  d i v i d e s and groundwater d i v i d e s  i s no c h a n g e i n g r o u n d w a t e r s t o r a g e , a n d  t h e r e a r e no e x t e r n a l i n f l o w s o r o u t f l o w s o f g r o u n d w a t e r , t h e n a w a t e r b u d g e t e q u a t i o n w o u l d be w r i t t e n  f o r an a n n u a l  period as follows, P=Q + Q sp  s a  -Qsac  +  °-sbm  where P i s t h e a v e r a g e a n n u a l  +  Qg  runoff  Q  s a  s  +E  w  precipitation, Q  f a c e w a t e r component o f a v e r a g e a n n u a l tation,  + E  <-> 4  s p  i s the sur-  r u n o f f due t o p r e c i p i -  i s t h e s u r f a c e w a t e r component o f a v e r a g e  due t o g l a c i a l  ablation, Q  s a c  annual  i s t h e s u r f a c e water  component o f a v e r a g e r u n o f f d u e t o g l a c i a l a c c u m u l a t i o n , is  2  t h e s u r f a c e w a t e r component o f a v e r a g e a n n u a l  Q bm s  r u n o f f due  58  to g l a c i a l  basal melting,  average annual soil-covered  runoff,  portion  Qg i s t h e g r o u n d w a t e r  E i s the evapotranspiration g  of the b a s i n ,  f r o m t h e open water p o r t i o n  Equation a  rigourous  4.2 i n c l u d e s  and a c c u r a t e  Meager.Mountain a r e a . variables,  ered the  negligible. continual  covers.  water b a l a n c e c a l c u l a t i o n i n t h e i s not a v a i l a b l e f o r a l l the  melting  so E  =  of the e a r t h  U.3)  Clark,  Lewis and Souther  II demonstrate that  melt  i s l e s s than  gnificant.  runoff  Qgj^  heat  flux  1%, a n d i s t h e r e f o r e  that  flux i s  Calculations recontributes a  i n t h e Meager  close  ice  communication,  c o n t r i b u t i o n f o r the e n t i r e  w h i c h has an o v e r a l l  of  (1978) d i s c o v e r e d ,  10 t i m e s t h e w o r l d a v e r a g e .  The b a s a l  average  (personal  the average geothermal heat  maximum o f 3 t o 4% o f t h e t o t a l basin.  of i c e with  P i s the density  flux,  of melting  t h e Meager C r e e k b a s i n  i n Appendix  the g l a c i e r  Ea.  G.  ported  represents  PL  L i s the l a t e n t heat  approximately  m  equation i s  i s the geothermal heat  1981).  very  c a n be c o n s i d -  d t i s t h e r a t e o f change o f t h i c k n e s s Q  place,  o f g l a c i e r s due t o t h e n a t u r a l  of t h e p o r t i o n  and  basin  In t h e f i r s t  s  basal  dz dt  tractable.  I n a d d i t i o n , t h e component Q b  The g o v e r n i n g  time, q  in  i s the evaporation  of the b a s i n .  e x i s t s i n the basin,  gradient  dz where  w  b u t a number o f s i m p l i f y i n g a s s u m p t i o n s c a n be  open water  geothermal  and E  from t h e  t h e m a j o r components n e c e s s a r y f o r  Data  made t o make t h e p r o b l e m little  component o f  Creek  Lillooet  to the world assumed t o be  insi-  59  M e a s u r e m e n t s of g l a c i e r not  been u n d e r t a k e n  i n the  a b l a t i o n or a c c u m u l a t i o n  study  shown by h i s t o r i c a l , b o t a n i c a l glaciers  i n the  retreating  ciers  and  however i t has  been  geological studies  that  C o a s t M o u n t a i n s of B r i t i s h C o l u m b i a have been  s i n c e the  (Mathews, 1 9 5 1 ) . nineteen  area,  have  s e c o n d and  This  fifties.  t h i r d decades of t h i s  r e t r e a t has  The  century  s l o w e d somewhat s i n c e  r a t e o f a b l a t i o n of a number of  in southwestern B r i t i s h  C o l u m b i a has  the  gla-  been i n v e s t i g a t e d .  Mathews ( 1 9 5 1 ) e x a m i n e d a number of g l a c i e r s i n t h e  Mount  Garabaldi  most com-  area  p l e t e data lossing 1928  t o 2.1  1947.  been s t u d i e d Pemberton. 0.4  m/y  the  tion  north  of V a n c o u v e r .  of w a t e r e q u i v a l e n t  glacier  nearest  the  i s t h e P l a c e G l a c i e r 20 From 1965  t o 1974  runoff  data  The  the  km  study  area  northeast  glacier  Stanley,  t o 1968.  r a t e of  basin.  basin. takes  o r 140  mm/y  The  1 m/y  has  time.  as  been c h o s e n f o r t h e  over the  r u n o f f , the  has  average  basin  allow  of  (Figure  of t h e  an  and  covers  the  average  g l a c i e r s of surface  area  glacier  slower ablathe of abla-  g l a c i e r s c o n t r i b u t e 0.14  entire drainage  above c o n s i d e r a t i o n s  that  This- time p e r i o d  Consequently, assuming that a l l the place  between  1976).  Therefore,  G l a c i e r s c o v e r 14%  be  of  l o s t an  r a p i d a b l a t i o n p e r i o d e a r l y i n the c e n t u r y in recent  found to  thickness  a v a i l b l e f o r the L i l l o o e t  i s a v e r a g e d f r o m 1923  Lillooet the  m/y  The  ablation period tion  km  ( M o k i e v s k y - Z u b o k and  The 4.3)  t o 80  e x i s t s f o r t h e Helm G l a c i e r , w h i c h was  1.8  and  40  m/y  basin. Equation  4.2  t o be  re-  60  duced t o p  -%>'W  %  +  E  The f a c t  that E  Equation  4.4 t o s i m p l i f y t o  s  (4.4)  i s t h e only e v a p o t r a n s p i r a t i o n term  P=Q  allows  -Q  + Q + E sp sac g where E i s t h e a v e r a g e a n n u a l e v a p o t r a n s p i r a t i o n .  (4.5)  The a v e r a g e a n n u a l r u n o f f , Qsp+Qsac" Qgf o v e r a 50 y e a r p e r i o d was g i v e n  earlier  t i o n E was e s t i m a t e d subtracting Q the L i l l o o e t  a s 1880 mm a n d t h e e v a p o t r a n s p i r a -  a t 500 mm.  A d d i n g t h e above v a l u e s and  g i v e s an a v e r a g e a n n u a l p r e c i p i t a t i o n P, i n b a s i n , of approximately  2240  mm.  )  We w o u l d a l s o l i k e values  of Q  s  and Q . g  t o gain  During  some i d e a o f t h e r e l a t i v e  t h e months o f J a n u a r y a n d  F e b r u a r y t h e mean a n n u a l t e m p e r a t u r e i n t h e L i l l o o e t below f r e e z i n g  (Table  4 . 1 ) , so t h a t a l l r u n o f f  comes f r o m g r o u n d w a t e r d i s c h a r g e  presumably  into the streams.  Figure  4.3 r e p r e s e n t s  t h e mean o f t h e mean d a i l y d i s c h a r g e  Lillooet  f r o m 1923 t o 1 9 6 8 .  River  or baseflow The s i m p l e s t horizontal begins,  technique  line  of baseflow  groundwater flow justifying  i s constant  the horizontal  The a r e a  runoff  T h i s method  assumes  That i s t o s a y , t h e  throughout the year,  line.  component  i s t o draw a  through the point a t which surface  groundwater flow system.  of the  from t h e graph.  separation  p o i n t A (Viessman e t a l . , 1977).  a steady-state  presents  The g r o u n d w a t e r  o f t h e r u n o f f c a n be c a l c u l a t e d  basin i s  thereby  below t h e l i n e r e -  t h e g r o u n d w a t e r component o f t h e a v e r a g e  annual  400  1  July Figure  4.3  Mean into  o f mean surface  daily water  discharge component  1  Aug  r  Sept  Nov  Dec  f o r L i l l o o e t R i v e r (1923-1968) divided Q p + Q and g r o u n d w a t e r component Q S  s a  g  62  r u n o f f Qg.  The a r e a a b o v e t h e l i n e  represents the surface  w a t e r component o f t h e a v e r a g e a n n u a l r u n o f f Q p Q s a c " +  T  S  a r e a below  the h o r i z o n t a l  line  i s 20% of t h e t o t a l  the c u r v e , t h e r e f o r e the groundwater  component Q  t h e a v e r a g e a n n u a l r u n o f f o f 1880 mm, In c o n c l u s i o n , the p r e l i m i n a r y equation f o r the L i l l o o e t  area  below  i s 20% o f  g  mm.  s i m p l i f i e d water balance  +  < -  E  4  w h e r e t h e a v e r a g e a n n u a l p r e c i p i t a t i o n P e q u a l s 2240 mm 6 1 % o r 1360 mm  of t h i s  total  i s released  , 17% o r 380 mm  5 )  and  f r o m t h e b a s i n by  t h e s u r f a c e w a t e r component o f t h e a v e r a g e a n n u a l r u n o f f to p r e c i p i t a t i o n Q  e  basin i s  - Qsp-Qsac Q g  P  o r 380  ^  by t h e g r o u n d w a t e r  due  com-  sp  ponent  of the average annual r u n o f f Q , g  t h e e v a p o t r a n s p i r a t i o n E.  and 2 2 % o r 500 mm  by  The s u r f a c e w a t e r component o f t h e  a v e r a g e a n n u a l r u n o f f due t o g l a c i a l  ablation Q  i s 140  mm/y. The c o n c l u d i n g e q u a t i o n i n d i c a t e s t h a t 17% o f t h e p r e c i pitation  falling  groundwater  i n the L i l l o o e t  system.  recharge w i l l  River basin enters the  I n C h a p t e r 6, t h i s v a l u e o f  groundwater  be c o m p a r e d w i t h t h e v a l u e c a l c u l a t e d  M e a g e r C r e e k s u b - b a s i n by a v e r y d i f f e r e n t m e t h o d .  i n the In  C h a p t e r 7, t h e v a l u e s a r e u s e d a s i n p u t p a r a m e t e r s i n t h e mathematical First,  model. we w i l l  Meager M o u n t a i n ductivity  discuss the f r a c t u r e  survey completed at  i n an a t t e m p t t o c a l c u l a t e  o f t h e f r a c t u r e d basement  rock.  the hydraulic  con-  63  C h a p t e r 5. HYDRAULIC CONDUCTIVITY OF FRACTURED ROCK The h y d r a u l i c for  conductivity  i s a very  determining groundwater flow  lier,  the hydraulic  conductivity  important parameter  patterns.  As s t a t e d  ear-  i n t h e Meager M o u n t a i n a r e a  i s g o v e r n e d m a i n l y by t h e f r a c t u r e p o r o s i t y o f t h e v o l c a n i c and  basement r o c k s .  that  Many r e s e a r c h e r s  relate the fracture porosity Snow  have d e v e l o p e d  n to the hydraulic  tivity  K.  planer  j o i n t s o f a p e r t u r e b, w i t h N j o i n t s p e r u n i t  a c r o s s t h e rock ctivity:  (1968) i l l u s t r a t e d  face . .  that  has a p o r o s i t y  formulas conduc-  a p a r a l l e l array of distance  n=Nb a n d h y d r a u l i c  condu-  / .\ (5.1)  or (5.2) where k i s t h e p e r m e a b i l i t y the  fluid,  of the rock,  P  i s t h e d e n s i t y of  g i s t h e a c c e l l e r a t i o n due t o g r a v i t y a n d y i s t h e  dynamic v i s c o s i t y  Therefore, the only  field  measurements n e c e s s a r y a r e t h e a p e r t u r e and s p a c i n g .  Note  that  of the f l u i d .  the hydraulic  aperture.  c o n d u c t i v i t y v a r i e s a s t h e cube of t h e  I t i sclear,  ture apertures w i l l  that  create  inaccurate  large errors  measurements of f r a c i n the estimated  con-  ductivity . More c o m p l e x e q u a t i o n s have been d e v e l o p e d f o r two a n d three  dimensional anisotropic  addition  flow  t o a p e r t u r e and spacing,  i n f r a c t u r e d rock.  In  s t r i k e and d i p measurements  64  are  a l s o needed.  not  be d i s c u s s e d  The e q u a t i o n s a n d t h e i r d e v e l o p m e n t here but the i n t e r e s t e d  t o Snow ( 1 9 6 6 , 1 9 6 9 ) , B i a n c h i Franciss  reader  of  (1977), and S t r e l t s o v a  (1976).  discussed  the  r e s u l t s a r e compared w i t h  permeability  below.  sing  To c h e c k t h e v a l i d i t y  of v a r i o u s  Firstly,  rock  published  however, p r o p e r  rocks w i l l  Fracture The  structural  data of t h e f r a c t u r e  field  mapping and d a t a  conductivity  sizes.  discussed.  The l a r g e s t  a r e seldom observed  tinuous d i s c r e t e breaks w i t h i n  i n surface  zones.  bedrock  photography.  expoThe  a r e j o i n t s which a r e d i s c o n t h e r o c k mass, commonly o c -  r e f l e c t i n g the tectonic  mass (Raven 1 9 8 0 ) .  discontinui-  such as major f a u l t s and shear  most common t y p e o f f r a c t u r e s  i n sets  Methods  fractures are large-scale  s u r e s b u t a r e e a s i l y i d e n t i f i e d by a e r i a l  curing  proces-  determination  s y s t e m i n a r o c k mass c o n t a i n s  features  These f e a t u r e s  of t h e survey,  Mapping and Data P r o c e s s i n g  fracture  t i e s of v a r i o u s  be  survey  types.  techniques f o r the hydraulic  fractured  conductivity  The r e s u l t s o f t h i s f r a c t u r e  are  of  s u r v e y was u n d e r t a -  a t Meager M o u n t a i n t o e v a l u a t e t h e h y d r a u l i c t h e basement r o c k .  i s referred  a n d Snow ( 1 9 6 9 ) , Rocha a n d  D u r i n g t h e summer o f 1980 a f r a c t u r e ken  will  h i s t o r y of the rock  T r a n s i t i o n a l between major f a u l t s and  j o i n t s a r e f r a c t u r e z o n e s composed o f c l o s e l y s p a c e d i n t e r connecting breaks.  Such z o n e s may have w i d t h s o f m e t e r s t o  65  tens  of  meters.  A number o f methods f o r m a p p i n g f r a c t u r e s y s t e m s have been d e v e l o p e d . technique s i s by  A method i n common use  originally  Piteau  employed f o r e x c a v a t i o n  (1971).  measuring tape along  i s the  The an  method c o n s i s t s of  exposed rock  s u r e m e n t s and  be  tinuity  recording  the  tape.  mea-  f o r each  The  discon-  include:  1  distance  2  rock  3  hardness  4  type of  structures  5  spacing  and  6  aperture  7  strike  8  dip  9  l e n g t h of d i s c o n t i n u i t y  from t r a v e r s e s t a t i o n t o  structure  types  10  infilling  11  water  12  roughness  13  waviness P i t e a u and  the  recorded  analy-  stretching a  f a c e and  i n t e r s e c t the  t h a t can  sampling  stability  geological d i s c o n t i n u i t i e s that features  line  (fault,  f r e q u e n c y of  Martin  joint  joint  etc)  sets  (1977) i n c l u d e g e n e t i c  above t e r m s t o i n s u r e u n i f o r m  recording  d e s c r i p t i o n s of  by d i f f e r e n t i n -  dividuals. Mapping a l o n g  level  l i n e s on  near v e r t i c a l  outcrops  neg-  66  lects  f r a c t u r e s i n the h o r i z o n t a l d i r e c t i o n .  mation from boreholes p l e t e the  can  be t r e a t e d as l i n e  three-dimensional  a s s e s s m e n t of  Fracture  infor-  s a m p l e s t o com-  fracture orienta-  tion . The portant  aperture  parameters with respect  determination, ure  of a d i s c o n t i n u i t y  i n the  and  field.  of d y e ,  lighted.  f l u o r e s c e n t l i q u i d dye. a developer,  up p h o t o s a r e t a k e n  and  f r a c t u r e s a r e made w i t h c a l i p e r s on j e c t e d on  a screen.  method b u t  apertures  The be  130  c a l l e d DISCODAT.  gathered  be  measured  d u r i n g a f r a c t u r e survey  t o manage.  S e v e r a l computer a n a l y s i s and  (1977) d e v e l o p e d It i s described  B o t h s u r f a c e and  l y z e d w i t h the D i s c o d a t a s s t e r e o n e t s , and  borehole  programs.  histograms  f r e q u e n c i e s of the a n g l e  d i s p l a y of Cruden, package  i n a p a r t of t h e P i t  Slope  Resources  f r a c t u r e d a t a may  be  ana-  O r i e n t a t i o n diagrams  such  o f r e l a t i v e and  of s t r i k e  can  based  a computer based  M a n u a l s e r i e s p u b l i s h e d by E n e r g y , M i n e s and Canada.  the  this  s t r u c t u r a l d i s c o n t i n u i t y d a t a h a v e been d e v e l o p e d . Herget  high-  percent.  systems f o r the storage,- r e t r i e v a l ,  Ramsden and  the  b l o w n up p i c t u r e s p r o -  m i c r o n s can  difficult  be  m e a s u r e m e n t s of  as  amount of d a t a  l a r g e and  f r a c t u r e s can  draw b a c k s t o  s m a l l as  that  Through  T h e r e a r e a few  w i t h a r e l a t i v e e r r o r of 3  im-  p a r a m e t e r t o meas-  Snow (1970) d i s c u s s e s a t e c h n i q u e  s o l v e n t s , and  Close  of t h e most  to hydraulic c o n d u c t i v i t y  a l s o t h e most d i f f i c u l t  i n v o l v e s p h o t o g r a p h y and use  i s one  cumulative  a r e p r o d u c e d by  the  67  Discodat  system,  plotting.  The l i n e s a m p l i n g  the D i s c o d a t sary data  s a v i n g c o u n t l e s s hours  system  of t e d i o u s manual  t e c h n i q u e f o r g a t h e r i n g data and  work w e l l t o g e t h e r t o p r o d u c e t h e n e c e s -  for fractured-rock-hydrology studies.  Meager M o u n t a i n  Fracture  Survey  D u r i n g t h e summer o f 1980 t h e a u t h o r a n d t h e e m p l o y e e s of  N e v i n , S a d l i e r - B r o w n and Goodbrande L t d . performed  orientation  s u r v e y on t h e basement g r a n o d i o r i t e  Reservoir area.  The p u r p o s e  i n the South  of t h e study f o r N e v i n ,  Brown a n d G o o d b r a n d e L t d . was t o g a i n s t r u c t u r a l geologic for  conductivity  Sadlier-  data f o r  i n t e r p r e t a t i o n and f o r t h e author t o c o l l e c t  hydraulic  a joint  data  calculations.  Results Twenty-five  l o c a t i o n s were e x a m i n e d .  were i n basement r o c k a n d one i n v o l c a n i c illustrates  the s i t e l o c a t i o n s .  Twenty-four rock.  sites  F i g u r e 5.1  The l i n e s a m p l i n g  technique  d e s c r i b e d e a r l i e r was n o t u t i l i z e d i n t h e s u r v e y b e c a u s e t h e a u t h o r was n o t aware o f t h e t e c h n i q u e a t t h e t i m e o f t h e s u r vey.  Rather,  t r a v e r s e s were made a l o n g o u t c r o p s a n d j o i n t s  were m e a s u r e d i n a random f a s h i o n . cent  joints  The s p a c i n g between a d j a -  o f t h e same s e t a n d t h e a p e r t u r e o f e a c h  fracture  were e s t i m a t e d r a t h e r t h a n m e a s u r e d d i r e c t l y . Lower h e m i s p h e r e ,  equal-area, contoured-pole  t h e t w e n t y - f i v e s i t e s c a n be f o u n d  i n Appendix  p l o t s of  I I along with  F i g u r e 5.1  Location of f r a c t u r e survey  sites.  69  t h e c o o r d i n a t e s and tion  of t h e c o n t o u r e d - p o l e  joint  Table  individual evident of t h e  5.1  joint  e x h i b i t s the v a r i a t i o n  joint  4 occur  and  2 are  o n l y a t a few  the  joint  The  variation  5.0  in spacing 5.3.  of t h e  that there  m and  sites,  and  s e t s where orientation  Note t h a t  site while  indicating rock.  joint  joint  sets 3  that joint  It is also  and  and  aperture  of  joint  sets  t h e a v e r a g e v a r i a t i o n s of  four j o i n t  s e t s are  i n Table  i s a w i d e r a n g e of s p a c i n g s  of a p e r t u r e s  from t i g h t  a l s o have a w i d e r a n g e .  the d i f f i c u l t y rock  of s e e i n g  the  t o 20 mm.  The  list  5.4.  parameter c o u l d not  neglect  to s t r e s s the  observations  be  f r o m 0.05  i m p o r t a n c e of t h e  to others  s i n g v a l u e s a t a number of  A l s o , the  s p a c i n g and  to the  values due  s e t s on  Consequently,  estimated.  It is  Therefore,  joint  can  spacing  i s incomplete  individual  f a c e s a t a number o f l o c a t i o n s .  spacing  tion  sets 1  clear  h y d r a u l i c c o n d u c t i v i t y which i s c a l c u l a t e d from these will  d i p of  sets are a l s o s t e e p l y d i p p i n g .  found i n Table  evident  in strike  s e t s at each measured s i t e .  the dominant s e t s i n the  aperture  identifica-  i l l u s t r a t e s the average  2 e x i s t at almost every  and  and  5.2  examina-  four p e r s i s t a n t  s e t s a t l o c a t i o n s where j o i n t  while Table  s e t s 1 and  be  p l o t s revealed  Close  s e t s t h a t have been h i g h l i g h t e d f o r e a s y  tion.  that  e l e v a t i o n of each s i t e .  to  the  the  joint  author's separa-  t a k i n g measurements, l e d t o missites'.  TABLE 5. 1 Orientation  J o i n t Set Site  1  Strike  J o i n t Set 2 Dip  1  350-35  2  45-75  70N  3  32-68  45NW-75SE  4  17-45  75SE-85NW  65W -88E  4-25  Strike  70E -80W  7 8  106-130  34  148-170  70W -75E  106-148  40  125-144  58  105-140  35  75S  -72SW  55-75  70  -90S  75SW  65-80  65  -88S  68-88  60  -88SE  65SW-80NE  154-166  60SW-80NE  10  25-40  68  148-170  70NE-80SW  150-165  62  136-162  70NE-80SW 60SW-78NE  -90NW  11 78SE-84NW 40  -80SE  38-66  42  -64NW  118-140  15  156-180  52  -78E  98-128  75NE-70SW  16  14-35  70SE-80NW  90-122  50  -90NE  17  4-25  72NW-80SE  18  0-36  70NW-68SE  110-158  40  -70SW  19  20-38  76NW-72SE  108-140  44  -75NE  148-176  70SW-70NE  20 164-28  70NW-62SE  32-76  64SE-72NW  22 23 24 25  Strike  Dip  -85N  75-105  35  -65N  68-110  20  -45N  90-116  40  -80NE  78-96  40  -60N  88-120  56  -80NE  72-118  20  -40N  -90NE  14  21  Dip  80-94  130-170  40-68  Strike  J o i n t Set 4  -60SW  78NW-82SE  13  3  -78NE  22-45  6-24  Sets  J o i n t Set Dip  9  12  of J o i n t  -75S  5 6  Variations  145-174  50NE-80SW  125-162  45  144-170  68NE-80SW  45-72  60  64-82  68NW-76SE  68-96  64  -70NE  -72SW -90S  TABLE Average  Joint Site  Set 1  Joint  Set 2  Dip  Strike  Dip  118  56 NE  159  87 SW  127  52 SW  1  12  82 NW  60  88 NW  3  50  75 NW  4  31  85  SE  5 6  Orientations  Strike  2  15  85  SE  5.2 of  Joint  Sets  Joint  Set  3  Joint Dip  Strike  Dip  87  85 S  90  50 N  89  33 N  135  65 SW  65  80 S  119  55 SW  72  77 S  8  150  82 SW 78  74 S  9  33  88 NW  160  80 SW  32  79 NW  159  85 NE  12  15  87  SE  13  54  60  SE  14  52  53 NW  11  15  158  76 NE  149  85 NE  129  86 SW  113  88 SW  106  70 NE  55 SW  16  24  85  17  14  86 NW  18  18  89  SE  134  19  29  88  SE  124  59 NE  162  90  SE  20 21  6  86  SE  22 23  54  86  SE  24 25  32  80 NW  159  75 NE  144  59 SW  157  84 NE  140  85 SW  4  Strike  7  10  Set  103  59  65 NW  73  86 NW  82  77 S  87 104  95  60 NE  50 N 69 NE  30 N  Table  5.3  J o i n t Spacing and Aperture V a r i a t i o n s Site  J o i n t Set  Spacing(m)  Aperture(mm)  1  1  0.2-1.0  2  1  0.1-0.5  3  1  0.5-1.0  3  2  0.1-1.5  5-2  0.4-2.0  4  1.3 & 4 2  Tight  -3 1-5  Tight  -5  1.0-5.0  Tight Tight -5  0.1-0.5  Tight  4  0.05-0.25  Tight  10  1  0.05-1.0  10  2  0.05-0.8  Tight  11  2  14  2  1-1.5 0.2-1.0  Tight Tight  8 9  2  9  14  1  0.3-0.5  15-18  1 & 2  0.1-1.0  Table  -10 -5 5-20 -5 2-20 -5 -3 1-10  5.4  Average Spacing and Aperture Set  Spacing(ra)  Aperture(mm)  1  0.1 -1.0  Tight  -20  2  0.1 -1.0  Tight  -20  3  0.4-2.0  4  0.05-2.0  Tight Tight  -5  73  Discussion The survey  m e t h o d o l o g y u s e d f o r t h e Meager M o u n t a i n  s u p p l i e d inadequate  data  f o r the c a l c u l a t i o n of the  r o c k mass h y d r a u l i c c o n d u c t i v i t y . survey sible  a r e l i s t e d below t o g e t h e r future  fracture  The p r o b l e m s w i t h t h e  with suggestions  f o r pos-  remedies.  1) The p r o b l e m o f t h e m i s s i n g d a t a  f o r s p a c i n g and a p e r t u r e  m e a s u r e m e n t s c o u l d be r e c t i f i e d dardizing 2) The s u r v e y s  survey  by c o o r d i n a t i n g a n d s t a n -  practice before  were t a k e n  beginning  t h e work.  on n e a r - v e r t i c a l o u t c r o p s ,  quently  t h e measured f r a c t u r e s r e p r e s e n t  sions.  The g a t h e r i n g o f j o i n t  bore h o l e s or near h o r i z o n t a l  conse-  o n l y two d i m e n -  orientations in inclined rock  faces would c o r r e c t  this deficiency. 3) The random m e a s u r i n g o f t h e j o i n t r e s u l t s , whereas t h e l i n e any  systems can b i a s the  sampling  technique  eliminates  bias.  4) The m a j o r p r o b l e m w i t h t h e m e a s u r e m e n t s t a k e n a t Meager Mountain l i e s  i n the fact  t u r e s were e s t i m a t e d  that the a p e r t u r e s of the f r a c -  r a t h e r than measured d i r e c t l y .  The  c o n d u c t i v i t y o f t h e r o c k mass v a r i e s a s t h e a p e r t u r e c u b e d , t h e r e f o r e i n a c c u r a c i e s i n a p e r t u r e measurement a r e m u l t i p l i e d when c a l c u l a t i n g flux  through  Simple  the h y d r a u l i c c o n d u c t i v i t y or  the rock.  h y d r a u l i c c o n d u c t i v i t y c a l c u l a t i o n s of the rock  mass were a t t e m p t e d  using Equation  5.1.  H o w e v e r , due t o t h e  74  variability  of a p e r t u r e  e s t i m a t e s a t any  hydraulic conductivity estimates over  (10  many o r d e r s of m a g n i t u d e and  have l i t t l e  value.  + 4  such  single  to 10"  site, m/s)  6  the  extended  e s t i m a t e s are  felt  E v e n i f more a c c u r a t e a p e r t u r e s had  been  m e a s u r e d , i t i s q u e s t i o n a b l e w h e t h e r t h e measurement of t u r e s on  ture  of rock at d e p t h .  A near-surface  i s widened d u r i n g i t s h i s t o r y ,  stress such  field  as w e a t h e r i n g  and  creep  60 m. an  rock p o r o s i t y decreases  Therefore,  unreasonably  ever,  by  ( B i a n c h i and  first an  of  surface  150  order  con-  frac-  the  processes  Snow, 1 9 6 9 ) .  in granitic,  v o l c a n i c rock, t h a t w i t h i n the  fractured  or s u r f a c e  by a d e c r e a s e  by e r o s i o n a l u n l o a d i n g and  (1968) d i s c o v e r e d f r o m t e s t h o l e s and  frac-  s u r f a c e exposures i s adequate f o r computing the  ductivity  Snow  metamorphic  m of d e p t h ,  of m a g n i t u d e  the every  s u r f a c e m e a s u r e m e n t s of a p e r t u r e s w i l l  h i g h c o n d u c t i v i t y f o r t h e r o c k mass.  f r a c t u r e d a t a can  be  used t o i l l u s t r a t e  to  general  give  Howtrends  o f t h e c o n d u c t i v i t y i n a r o c k mass, s u c h as t h e d i r e c t i o n anisotropy.  A l s o , areas  of r e l a t i v e l y  high fracture density  can  be d e l i n e a t e d t o p o s s i b l y r e v e a l z o n e s o f h i g h e r  lic  c o n d u c t i v i t y at In the  later  measure a p e r t u r e s  and  tests  packer  s t a g e s o f e x p l o r a t i o n i t may in-situ  As-, t h e  in boreholes of c o u r s e ,  fracture  be  be p o s s i b l e t o  w i t h a down-hole  once a h o l e  f o r h y d r a u l i c c o n d u c t i v i t y such  t e s t s can  hydrau-  depth.  c a m e r a o r p e r i s c o p e , and direct  of  is drilled,  as pump t e s t s  performed.  survey  a t Meager M o u n t a i n was  unsucces-  75  sful,  l e t us  various vity  now  rock  values  look at p u b l i s h e d  types,  t o o b t a i n a range of h y d r a u l i c  t h a t one  Published  f r a c t u r e p e r m e a b i l i t i e s of  might expect  Fracture  i n the  study  conducti-  area.  P e r m e a b i l i t i e s of V a r i o u s  Rock T y p e s  R e p o r t e d m e a s u r e m e n t s of h y d r a u l i c c o n d u c t i v i t i e s i n fractured research ken  rock  1970's.  Canada L i m i t e d  Work p e r f o r m e d  (AECL) and  Gale  S u r v e y o f Canada and s t r u c t u r e s and  m i n e s , l o c a t e d on s e e p a g e was tures  s u c h as  D e p a r t m e n t of E n e r g y  values.  AECL, e x a m i n e d t h e  surface  and  groundwater c o n d i t i o n s at Canadian S h i e l d . t o the  u p p e r 300  f a u l t s or c o n t a c t s number and  zones, d i k e s , Of  the  sills  I t was m i f no  were p r e s e n t .  sets continued rock  underground  found  that  major s t r u c They a l s o  t o 350  m.  t o d e p t h s o f up near s u r f a c e  values,  t o 1000  conductishear  contacts.  25 mine s i t e s e x a m i n e d , t h e most e x t e n s i v e  gram of down h o l e  m  decreased  f o l l o w e d by  i n t r u s i v e geologic  seep-  Struc-  I n t e r m s of h y d r a u l i c  the h i g h e s t and  25  subsur-  m a g n i t u d e of t h e s e s t r u c t u r a l  l o g a r i t h m i c a l l y with depth. f a u l t s provide  has  Geological  t h e p e r m e a b i l i t i e s of t h e  vity,  of  f o r the  the  joint  underta-  f o r the Atomic Energy  z o n e s were g r e a t l y r e d u c e d b e l o w 300  tures but  the  r e c e n t l y , when  in a report  restricted  s u c h as  found t h a t age  t h e U.S.  (1977),  until  w a s t e r e p o s i t o r i e s was  most of t h e p u b l i s h e d  Raven and  face  scarce  for f e a s i b l e nuclear  i n the  provided  have been v e r y  h y d r a u l i c c o n d u c t i v i t y t e s t i n g was  pro-  carried  76  out a t the G u l l were d r i l l e d g n e i s s , and tivity 10"  8  from  10"  inflow tests  to 10"  draulic 10" 500  5  7  m/s,  The  t o 10"'  From 60 t o 150  m the  to hy-  variation. .  AECL r e p o r t , d i s c u s s e s f o r the  cons-  Swedish  t e s t h o l e s were sunk o v e r  p l u t o n i n the Precambrian  basement.  Hy-  m varied  from  i n t h e u p p e r 100  d e c r e a s i n g t o 10""  to 10"  500  m/s  1 0  from  200  to  m. Raven  Nuclear  (1979) c o l l e c t e d h y d r o g e o l o g i c d a t a  f o r the  F u e l Waste Management P r o g r a m a t t h e C h a l k  (Ontario) Nuclear and  holes  biotite  and d e c r e a s e d  i n 8 boreholes completed  conductivity values  to 10"  m/s  significant  i n another  R a d i o a c t i v e Waste P r o g r a m . m into a granitic  6  showed no  (1979),  The  Near s u r f a c e , the h y d r a u l i c conduc-  o f 60 t o 75 m.  conductivity  Burgess  5  in Labrador.  g r a n o d i o r i t e , hornblende  amphibolite.  at depths  draulic  tant  in foliated  varied  m/s  Island project site  1978.  Laboratories f i e l d  research site  V a r i o u s s h u t - i n p r e s s u r e and  accomplished  in 5 test holes d r i l l e d  g n e i s s and m e t a g a b b r o . 4x10"' t o 4 x 1 0 "  1 1  River  injection  in  1977  tests  i n Precambrian  were  monzonite  H y d r a u l i c c o n d u c t i v i t y v a l u e s of  were o b t a i n e d a t d e p t h s  b e t w e e n 40 and  72  m. Davison  e t a l . (1979) r e p o r t e d on v a r i o u s down h o l e  t e s t s performed Nuclear  Research  completed  i n two  in a granitic Establishment drill  p l u t o n at the W h i t e s h e l l i n Manitoba.  h o l e s e a c h 150  h y d r a u l i c c o n d u c t i v i t y v a l u e s of 5x10"  m deep. 8  The  tests  were  Above 25  t o 5 x 1 0 " ' m/s  m  were  77  obtained. 5x10'  Below 25 m t h e h y d r a u l i c c o n d u c t i v i t y r a n g e d  to 5x10"  1 0  m/s.  1 1  O v e r t h e p a s t 10 t o 15 y e a r s , e x t e n s i v e d r i l l i n g hydrogeologic  t e s t i n g has  B a s a l t Waste I s o l a t i o n  been u n d e r t a k e n  at the  o f a number of t h i c k  vity  are  5x10" ty  from 5 x 1 0 " m/s  1 3  maximum v a r i a t i o n s 1  m/s  i n very  The  basaltic  w i t h m i n o r b r e c c i a t e d o r w e a t h e r e d h o r i z o n s and The  and  Hanford,  P r o j e c t i n Washington S t a t e .  logy c o n s i s t s b a s i c a l l y  interbeds.  from  geo-  flows  sedimentary  i n the h y d r a u l i c c o n d u c t i -  sandy w e a t h e r e d l a y e r s t o  i n v e r y dense columnar b a s a l t zones.  The  majori-  of t h e w e a t h e r e d , b r e c c i a t e d z o n e s have h y d r a u l i c c o n d u c -  tivity  values  ranging  from 10"  3  d e n s i t y b a s a l t s r a n g e f r o m 10"' d e n s i t y b a s a l t flows vary Davis  to 10' to 10'  f r o m 10"'  m/s.  5  Most of t h e  m/s  1 0  to 10'  and  high  m/s.  1 0  (1969) r e p o r t e d i n h i s p a p e r on  the  t h e p o r o s i t y and  p e r m e a b i l i t y of v a r i o u s m a t e r i a l s i n c l u d i n g p l u t o n i c , c a n i c , m e t a m o r p h i c and deposits.  sedimentary  H i s f i n d i n g s on  number of r o c k  types are  r o c k s and  vity  preceding  summarized i n Table  values  given turbed  I t s h o u l d be  noted  lies  i n the 10'  5.5  along  with  above.  7  to 10'  m/s  1 1  t h a t , t h e m a j o r i t y of t h e  i n t h e v a r i o u s r e p o r t s were t a k e n rock.  unconsolidated  imply t h a t the h y d r a u l i c c o n d u c t i -  of most f r a c t u r e d r o c k  range.  vol-  the h y d r a u l i c c o n d u c t i v i t y of a  the o t h e r h y d r a u l i c c o n d u c t i v i t i e s d i s c u s s e d The  low  in reasonably  values undis-  However, t h e basement r o c k s o f t h e Meager  M o u n t a i n a r e a have been h i g h l y d i s t u r b e d .  Therefore, i t  Table  5.5  Summary o f Measured H y d r a u l i c C o n d u c t i v i t y V a l u e s f o r Various  Reference  Raven and G a l e  Rock Types  Location  1977  Gull  Island  Rock Type  Foliated  granodiorite  and b i o t i t e Burgess  1979  Sweden  Granite  gneiss  pluton  Depth  (m)  20 60-75 0-100 200-500  Raven  1979  Davison, Grisak Williams  Chalk River and  Ontario  W h i t e s h e l l Manitoba  Monzonite Granite  gneiss  pluton  1979  Rockwell I n t e r n a t i o n a l  H a n f o r d Washington  Davis  1969  Dense  basalt  pumecious  tuff  - 5  to  IO  - 6  -  IO  - 8  10  - 5  -  io  - 7  10"  8  -9  4x10  25  5xl0~  -  Basalt  IO  150  1979  Conductivity  8  5X10" 4xl0~ 10" IO"  1 0  7  metasediments  3xl0~  7  greywacke  4xl0~  7  1 0  1 0  10  IO"  (m/s)  - 6  1 0  -1 1  -  4x10  -  5xl0~  9  -  5X10"  1 1  -  4xl0"  1 3  79  w o u l d be e x p e c t e d of  t h a t the h y d r a u l i c c o n d u c t i v i t y v a l u e s  t h e basement r o c k s a r e a t t h e h i g h end  stated. In  Values  of 10"  7  the hydrogeology  t o 10"  8  m/s  c h a p t e r and  ctivity  o f t h e basement r o c k a p p a r e n t l y f a l l s  8  m/s  range.  range  expected.  mathematical  to follow,  10'  be  c o u l d be  chapter  to  it will  of the  of  modelling  shown t h a t t h e h y d r a u l i c c o n d u into this  10"  7  80  C h a p t e r 6. HYDROGEOLOGY H y d r o g e o l o g y c a n be d e f i n e d a s t h e s c i e n c e t h a t with the occurrence, d i s t r i b u t i o n ter.  Three  deals  a n d movement o f g r o u n d w a -  important a s p e c t s of t h e hydrogeology of the  Meager M o u n t a i n a r e a w i l l table configuration,  be a d d r e s s e d .  the hydraulic  These a r e t h e water  c o n d u c t i v i t y of the  v a r i o u s g e o l o g i c a l m a t e r i a l s , a n d an e s t i m a t e o f t h e amount of  groundwater  hydrogeology  recharge.  The f o l l o w i n g  i s b a s e d on t h e l o c a l a n d r e g i o n a l g e o l o g y , t h e  l o c a t i o n and n a t u r e of t h e h o t and c o l d hydraulic  Figure  divide  and g e n e r a l  field  6.1 i s a c r o s s s e c t i o n  schematically  system.  springs,  c o n d u c t i v i t y v a l u e s of f r a c t u r e d  balance c a l c u l a t i o n s ,  showing  i n t e r p r e t a t i o n of the  rock, t h e water  observations.  t h r o u g h Meager M o u n t a i n  t h e g e n e r a l flow of groundwater  L i n e CD r e p r e s e n t s t h e l o c a t i o n i n the mountain.  t h e groundwater  d i s c h a r g e i n t h e Meager  v a l l e y w h i l e a l l the water e n t e r i n g  discharge into the L i l l o o e t  River valley.  p a t h than t h e water of t h e Pebble Creek H o t s p r i n g s ,  Brown  Creek  t h e system n o r t h of the  w a t e r o f t h e Meager C r e e k H o t s p r i n g s h a s a d i f f e r e n t  dissimilar  i n the  of t h e groundwater  A l l water e n t e r i n g  zone s o u t h of t h e l i n e w i l l  line will  published  The flow therefore  w a t e r g e o c h e m i s t r i e s f o u n d by Hammerstrom a n d  (1977) a r e n o t s u r p r i s i n g . The M e a g e r C r e e k s i d e o f t h e m o u n t a i n  greater data a v a i l a b i l i t y  ( s e c t i o n CDEF) h a s  a n d more g e o t h e r m a l p r o m i s e t h a n  PYLON PEAK  CAPRICORN MOUNTAIN  Kilometres  Flow Lines  Figure  6.1  General  groundwater  flow  Water Table  i n Meager  Mountain.  82  the  Lillooet  cussion  River  s i d e , so i t w i l l  be u s e d f o r f u r t h e r  dis-  i n t h i s c h a p t e r a n d t h e f o l l o w i n g c h a p t e r on m o d e l -  ling .  Water T a b l e The  water t a b l e c o n f i g u r a t i o n  determines the gradient flow  Configuration  or d r i v i n g  a t Meager M o u n t a i n .  Recall  i s important because i t force  f o r the groundwater  from Chapter 3 t h a t  the g r a -  dh  dient  i n D a r c y ' s Law i s ^ j - where dh i s t h e c h a n g e i n h e a d  over a change i n d i s t a n c e configurations water t a b l e  i n Figure  dl. 6.2.  s o , by d e f i n i t i o n ,  C o n s i d e r t h e two P o i n t s , A,C,D  is  The h e a d d r o p f r o m A  than from D t o F and y e t t h e change i n 1  t h e same i n b o t h c a s e s .  when t h e w a t e r t a b l e  a n d F a r e on t h e  t h e head a t t h e s e p o i n t s i s  equal t o the e l e v a t i o n of the p o i n t s . t o C i s much g r e a t e r  water-table  Therefore, the gradient  i s higher.  A higher  gradient  i s larger causes  more w a t e r t o move t h r o u g h t h e s y s t e m p e r u n i t t i m e ,  leading  t o a l a r g e r volume of w a t e r t o d i s c h a r g e i n t h e v a l l e y Little  i s known a b o u t t h e w a t e r t a b l e c o n f i g u r a t i o n i n  mountainous regions.  I t i s n o t known w h e t h e r i t s i t s h i g h i n  most m o u n t a i n s o r i s r e l a t i v e l y  flat.  p e n d s on t h e h y r a u l i c c o n d u c t i v i t y of  recharge a v a i l a b l e .  observed that of  area.  o f t h e r o c k a n d t h e amount  I n areas of r o l l i n g h i l l s  i t has been  t h e w a t e r t a b l e t e n d s t o be a s u b d u e d  the topography A highly  The c o n f i g u r a t i o n d e -  replica  ( F i g . 4.6).  elevated  water t a b l e would lead  to the develop-  83  Figure  6.2  W a t e r t a b l e e l e v a t i o n and s e e p a g e development.  face  84  ment o f s e e p a g e f a c e s [Fig.  on t h e s i d e o f t h e m o u n t a i n  6 . 2 ( a ) ] where t h e w a t e r t a b l e  i n t e r s e c t s the surface.  T h e s e z o n e s w o u l d be t h e s i t e o f many s p r i n g s . very  few s p r i n g s  large extent discharge the  were o b s e r v e d a n d no m a j o r s e e p a g e a r e a s o f  occur.  One  I t seems l i k e l y  s i t u a t e d at a high  elevation  o c c u p i e s a more i n t e r m e d i a t e physically possible  to  unconsolidated that  the water t a b l e i s  i n the mountain but r a t h e r  p o s i t i o n [ F i g . 6.2(b)].  The will  chapter.  Hydraulic  C o n d u c t i v i t i e s of the Geologic  The o t h e r  parameter g o v e r n i n g t h e groundwater f l o w , be-  sides  the water-table  tivity  the geologic  t h e y must be d i v i d e d ductivity graphic extent  condiguration  Materials  i s the hydraulic  conduc-  K.  To e v a l u a t e  materials  i n t o groups w i t h  characteristics.  Maxey  u n i t s as "bodies of rock t h a t compose a g e o l o g i c  distinct  hydrologic  system."  2, t h e f r a c t u r e h y d r a u l i c  flow  system i s c o n f i n e d  range of water t a b l e c o n f i g u r a t i o n s  be c a l c u l a t e d i n t h e n e x t  the  l e d to believe that the  o f t h e v a l l e y o v e r l a i n by  Quaternary deposits. not  i s therefore  area f o r the groundwater flow  sections  In the f i e l d ,  volcanic  hydrogeologically  similar  hydraulic  con-  (1964) d e f i n e s h y d r o s t r a t i with considerable  lateral  framework f o r a r e a s o n a b l y As m e n t i o n e d e a r l i e r  i n Chapter  c o n d u c t i v i t y that occurs across a l l  l a y e r s has g r e a t e r  c o n t r o l over the groundwater  than the i n t e r g r a n u l a r h y d r a u l i c  conductivity d i f -  85  f e r e n c e s between l a y e r s . pile ter  c a n be c o n s i d e r e d flow.  Consequently, the e n t i r e  a s one u n i t w i t h  respect  volcanic  t o groundwa-  The basement a n d t h e u n c o n s o l i d a t e d  deposits r e -  p r e s e n t two o t h e r u n i t s t h a t would have c h a r a c t e r i s t i c hydraulic  conductivities.  Therefore, the g e o l o g i c a l  i n t h e M e a g e r M o u n t a i n a r e a c a n be d i v i d e d  formations  into three  hydros-  tratigraphic  u n i t ; t h e v o l c a n i c s , t h e b a s e m e n t , a n d t h e un-  consolidated  Quaternary d e p o s i t s .  hydraulic  c o n d u c t i v i t y h a v e been made b u t a r a n g e c a n be i n -  voked f o r each h y d r o s t r a t i g r a p h i c The.unconsolidated deposits  that  t h i n l a y e r s of c l a y .  that  these deposits range 1 0 " The  River  valleys.  D r i l l i n g has  5  s h o u l d have h y d r a u l i c  to 10"  hydraulic  F r e e z e and C h e r r y  2  (1979) e s t i m a t e  conductivities in  m/s.  conductivity  of the g r a n o d i o r i t e  z o n i t e b a s e m e n t i s due t o f r a c t u r e p e r m e a b i l i t y . data discussed  previously  survey revealed  that  from 1 0 "  horizontal lic high  conductivity a s 1:5.  7  to I O  conductivity  Accordingly,  The  by K  x  sets  greater  I f we d e n o t e t h e and v e r t i c a l  by K , t h e n t h e r a t i o o f K : K z  base-  m/s.  - 6  t h e r o c k t o have a  i n the v e r t i c a l d i r e c t i o n .  hydraulic  Published  t h e two d o m i n a n t f r a c t u r e  have a near v e r t i c a l d i p , c a u s i n g conductivity  a n d mon-  suggest the h i g h l y d i s t u r b e d  ment w o u l d have a c o n d u c t i v i t y fracture  fill  t h e sediments a r e m a i n l y sands and b o u l d e r s  with  the  unit. e x i s t mainly as v a l l e y  i n t h e Meager Creek and L i l l o o e t revealed  No d i r e c t m e a s u r e m e n t s o f  X  Z  hydrau-  may be a s  the v e r t i c a l hydraulic  conductivi-  86  ty  i n the  while  basement r o c k p r o b a b l y v a r i e s f r o m 1 0 "  the  horizontal hydraulic  from 2 x l 0 " The  volcanic  b r e c c i a and cussed  t o 2x10"'  8  ash  the in  layers  with  with  m/s  C o n s i d e r , the breccia  f l o w and  include 10"  m/s  and  there  i s extensive  volcanics 1:1  or  would not  The  were n o t , contact;  one  f o r the  3.10,  the  assemblage  Typi-  7  m/s.  vertical  the  10" By  equivalent  horizontal  anisotropic As  stated  hydrau-  ratio earlier,  fracturing  anisotropy r a t i o s of  8  assemblage i s  to near v e r t i c a l  Anisotropic  layers,  breccia,  calculated  The  reduce the  flow.  weathered zone.  f o r the  z  in  flow  f o r the  a p p r o x i m a t e l y 16:1.  that w i l l  in  p o s s i b l y as  greater  than  low 5:1  expected.  vertical  very s i m i l a r  and  m/s  7  an  o v e r l a i n by a  calculated equivalent  isotropic. be  m/s  5  i s 3x10"  x  i s therefore,  Z  10"  conductivity K  the  conductivity K  on  tuff  typical  different  1.9x10"  X  or  dis-  being greatest  the  hydraulic  as  conductivity  of  As  volcanics  c o n d u c t i v i t y v a l u e s of  vertical  K :K  the  layers.  of  E q u a t i o n s 3.9  8  flow  top  f r o m T a b l e 5.5  f o r the  varies  media  the  invoking  the  the  of a b a s a l  hydraulic  taken  lic  layering gives  a t h i n weathered h o r i z o n  cal  a multilayered  interbedded with  horizontal direction. 6.3  m/s  8  m/s.  i n Chapter 4 the  Figure  conductivity probably  r o c k s t e n d t o be  o v e r a l l anisotropy  to 10'  7  conductivity  to that  of  the  K  z  of t h e  underlying  would expect e x t e n s i v e  i n the  field,  very  few  are  volcanics  must  basement r o c k .  spring  be If i t  l i n e s at. t h e i r  in evidence.  Consequent-  87  ,  JL 1^n  WEATHERED  K -  lO^tn/e K  10 m  FLOW  10 m  B R E C C I A K = 10  K «  2  = 1.9 x 1 0 " m / s 8  10" m/8 8  K  m/s  x  = 3.0 x 10" m/s 7  1 Figure  Figure  6.3  6.4  Equivalent hydraulic layered volcanics.  Cross-section location.  of  conductivity  Meager  Creek  at  in  stage  88  ly,  the v e r t i c a l  h y d r a u l i c c o n d u c t i v i t y i n the v o l c a n i c s p r e -  sumably r a n g e s from 1 0 "  t o 10""  7  m/s  hydraulic conductivity i s similar times  w h i l e the  horizontal  o r up t o a maximum of  5  greater.  Estimates  of G r o u n d w a t e r  Recharge  I n t h e Meager C r e e k b a s i n t h e o n l y h y d r o l o g i c a l m e a s u r e ments a v a i l a b l e  i n 1980  were r i v e r  Meager C r e e k H o t s p r i n g s are  bridge  reported i n Appendix I I I .  l e v e l of the stream  surface.  c h a r g e measurement i f t h e  stages  i n 1979. A river I t can  stream  i f the On  July  t i o n was Any  stream 4,  taken  stage  velocity  1980  s t a g e , can  stage  turned  level  velocity  river  reading then  of the stream,  at  sta-  stage  to a  any  be c a l c u l a t e d u s i n g t h e M a n n i n g e q u a t i o n .  This measure-  see  IV.  In Chapter January  stage  ( F i g . 6.4).  F o r an e x p l a n a t i o n of t h e M a n n i n g e q u a t i o n  Appendix  dis-  be c o n v e r t e d  a l l o w s d i s c h a r g e v a l u e s t o be c o m p u t e d f o r any ment.  into a  the  of a c r o s s - s e c t i o n a r e a )  p r e v i o u s l y can The  i s simply  i s known.  along with a r i v e r  cross-sectional area.  the  These measurements  a c r o s s s e c t i o n at the  reading taken  at  bottom c o n f i g u r a t i o n i s  known ( t h i s a l l o w s t h e c a l c u l a t i o n and  be  recorded  and  charge w i l l  3 i t was  February  noted  i t can  be e n t i r e l y  t h a t d u r i n g t h e months of  be e x p e c t e d  s u p p l i e d by  t h a t the  river  groundwater flow.  d i s c h a r g e a t t h e Meager C r e e k s t a t i o n d u r i n g J a n u a r y  disIf  and  the  89  February  c o u l d be c a l c u l a t e d ,  d i s c h a r g e and r e c h a r g e estimated.  Recall  then  t h e amount o f g r o u n d w a t e r  taking place  from Chapter  groundwater flow, the recharge  i n t h e b a s i n c o u l d be  3 t h a t , assuming steady  state  t o t h e s y s t e m must e q u a l t h e  di scharge. S t a g e r e a d i n g s were n o t t a k e n one r e a d i n g t a k e n  3  River station  the past  V ) , i t a p p e a r s t o be an a v e r a g e d a y .  on December 10 i s a l s o a r e a s o n a b l e  3 years  We c a n t h e r e -  representation for that  l i n e s a r e drawn a c r o s s  4.3, t h e g r a p h o f t h e a v e r a g e d a i l y River.  The b o t t o m d a s h e d l i n e ,  discharge  discharge.  The u p p e r d a s h e d - d o t t e d  December d i s c h a r g e . discharge  It i s clear,  i s approximately  Figure  of t h e L i l l o o e t  discussed e a r l i e r ,  base f l o w s e p a r a t i o n l i n e o r t h e a v e r a g e  flux  station  of year. N o t e , t h a t two h o r i z o n t a l  call,  to a  n o r t h o f P e m b e r t o n on December 1 0 ,  f o r e assume t h a t t h e m e a s u r e d d i s c h a r g e a t t h e Meager  time  but  Comparing the discharge at the  1979 w i t h o t h e r December d i s c h a r g e s o v e r (Appendix  or February  on December 1 0 , 1979 w h i c h c a l c u l a t e s  d i s c h a r g e o f 3.7 m /s. Lillooet  i n January  i s the  January-February  l i e r e p r e s e n t s t h e mean that the  January-February  7 0 % t h a t o f December.  Also re-  from Appendix I , t h a t t h e c a l c u l a t e d b a s a l g l a c i e r i n t h e Meager C r e e k b a s i n s u p p l i e s 0.09 m /s 3  the r u n o f f . be r e d u c e d another  The known December d i s c h a r g e  o r 4% o f  r a t e must t h e r e f o r e  by 30% t o r e p r e s e n t J a n u a r y - F e b r u a r y  4% t o r e p r e s e n t  melt  d i s c h a r g e and  the groundwater d i s c h a r g e  component  90  of  the r u n o f f .  2.5  m /s  o r 7.9  3  lying  Consequently, the groundwater m /y.  The  3  the stage s i t e  discharge  measured a r e a of t h e b a s i n  i s 2.18x10  m,  s  2  therefore,  the  is supp-  portion  of t h e a n n u a l p r e c i p i t a t i o n o v e r t h e d r a i n a g e b a s i n  that  enters  the groundwater  system  i s 0.36  an a n n u a l p r e c i p i t a t i o n o f 2.5 lates well with precipitation Lillooet  the groundwater  m/y.  m/y  or 14.5%;  assuming  This  percentage  corre-  component o f t h e t o t a l  c a l c u l a t e d from the water  River  (16.5%)  assume t h e v a l u e s  i n Chapter  of d i s c h a r g e  4.  annual  b a l a n c e f o r the whole  We  can  accordingly  c a l c u l a t e d are reasonably cor-  rect . Figure the  hydrogeology  tropic cally lic  illustrates  the c o n c l u s i o n s  o f t h e s o u t h s i d e o f Meager M o u n t a i n  a n i s t r o p i c g r a n o d i o r i t e basement.  c o n d u c t i v i t y o f t h e g r a n o d i o r i t e and  fill  an  schematically  to h o r i z o n t a l l y a n i s t r o p i c volcanics o v e r l i e a  similar.  m/y  6.5  Very permeable,  the v a l l e y bottom  litative  takes place.  p o s i t i o n i n the mountain  r a n g e s , and  u s e d as i n p u t derstanding  flux  vertihydrau-  The  water  complex.  table  of  0.36  table These  has qua-  configuration,  t h r o u g h t h e s y s t e m c a n now  hydrogeology.  Iso-  deposits  discharge  i n t o a m a t h e m a t i c a l model t o q u a n t i f y  of t h e  .  the v o l c a n i c s i s  where a g r o u n d w a t e r  i n t e r p r e t a t i o n s of the water  conductivity  vertical  i s o t r o p i c unconsolidated  over the d r a i n a g e b a s i n intermediate  The  on  our  be un-  Area of Outflux into Unconsolidated Valley Fill  GRANODIORITE  K  metres  6340  EXPECTED RANGE OF VALUES (m/s)  K v z  K  v x  10"  =10'  K =10"  7 _  6.6  7_  0 2  10"  8  Outflux •  -10" 10"  K  Figure  u z  u x  6.5  - 10"2 _ 10" »10"  2_  IO"  Summary Creek.  Approximate Water Table Location  8  Kgx-10- 7.5 - 1 0  K  0.36 m/y  -  8.5  6  6  o f the hydrogeology  on t h e s o u t h o f Meager  92  C h a p t e r 7. GROUNDWATER MODELLING C o m p u t e r - b a s e d n u m e r i c a l m e t h o d s a r e one o f t h e m a j o r t o o l s used problems  for solving  (Bear 1979).  l a r g e - s c a l e groundwater  W i t h t h e r e c e n t advance of computer  t e c h n o l o g y , much e f f o r t of  forecasting  h a s been d e v o t e d t o t h e d e v e l o p m e n t  techniques f o r numerical s o l u t i o n of the p a r t i a l  tial  e q u a t i o n s t h a t govern t h e f l o w of water  logical  environments.  readily  available  i n v a r i o u s geo-  The end p r o d u c t o f t h i s  been a number o f c o m p u t e r p r o g r a m s w h i c h t o any u s e r .  differen-  r e s e a r c h has  i n most c a s e s a r e  With m o d i f i c a t i o n s a hydro-  g e o l o g i s t c a n u s u a l l y make an a v a i l a b l e p r o g r a m a p p l i c a b l e t o her o r h i s s p e c i f i c  problem.  F r e e z e and C h e r r y  (1979)  describe mathematical modelling  as a f o u r - s t a g e p r o c e s s i n v o l v i n g p h y s i c a l problem,  2) r e p l a c e m e n t  1) an e x a m i n a t i o n o f t h e o f t h e p h y s i c a l p r o b l e m by  an e q u i v a l e n t m a t h e m a t i c a l p r o b l e m , m a t i c a l problem interpretation physical In  3) s o l u t i o n  w i t h a c c e p t e d m a t h e m a t i c a l t e c h n i q u e s , a n d 4) of the mathematical  results  i n terms  of the  problem. this  study groundwater  t e r m i n i s t i c m a t h e m a t i c a l model. l a w s , n o t on s t a t i s t i c a l  flow i s s i m u l a t e d u s i n g a deI t i s based  or empirical  on p h y s i c a l  relationships.  e q u a t i o n o f f l o w f o r t h i s work i s s o l v e d flow.  o f t h e mathe-  The  for steady-state  93  Mathematical  m o d e l s of g r o u n d w a t e r f l o w t a k e  boundary v a l u e problems.  To  problem for steady-state 1)  the  of  flow w i t h i n the  the  s i z e and  fully  r e g i o n of  r e g i o n , 4)  hydraulic conductivity values  the  i n the  m a t i c a l method o f s o l u t i o n ( F r e e z e  tion  aspects  will  be  discussed  strategy section.  s u l t s and  the  h o w e v e r , an  u s e d and  their capabilities  examination  The has  i s in  modified  and  u s e d two  the  s e c o n d was  The ties.  1) The  w r i t t e n by  S.P.  the author  r e g i o n of  s i z e o r s h a p e ; 2)  can  t a k e on any  1979).  i n the  A l l of  simula-  be  re-  discussed. programs  flow  different  programs  i s known as  FEPS;  Neuman o f t h e U n i v e r s i t y of  has  programs have the  any  5) a mathe-  i n Meager M o u n t a i n .  F r e e z e and  i s known as FREESURF1.  two  of  Computer Program  w r i t t e n by R.A.  by  around  order.  first  FEPS p r e p a r e d  Cherry,  of t h e c o m p u t e r  The  and  r e g i o n , and  results will  t h e a n a l y s i s of g r o u n d w a t e r f l o w  Arizona  equation  spatial distribution  and  for  was  f l o w , 2) t h e  subsequently  s i g n i f i c a n c e of t h e  author  n e e d s t o know  Then, the m a t h e m a t i c a l m o d e l l i n g  Firstly,  The  f l o w , one  of  value  r e g i o n , 3) t h e b o u n d a r y c o n d i t i o n s  b o u n d a r i e s of t h e  these  form  d e f i n e a boundary  subsurface  shape o f t h e  the  A modified  version  of  been renamed FOPS. following similar  capabili-  i s t w o - d i m e n s i o n a l but  can  have  the h y d r a u l i c c o n d u c t i v i t y d i s t r i b u t i o n  d e s i r e d c o n f i g u r a t i o n or range of v a l u e s ;  t h e h y d r a u l i c c o n d u c t i v i t y can  take  on  any  direction  and  3)  94  d e g r e e of a n i s o t r o p y ; 4) of  f i v e p o s s i b l e boundary c o n d i t i o n s .  t i o n s a r e , a)  face  (water  flux  t a b l e ) on  handle,  t a i n s an a x i a l interior  the  s e e p a g e f a c e s where t h e  e a r t h dam.  two  s y s t e m , d)  For  the  be  finite-  i n many ways b o t h  output  hydraulic posed over  by b o t h  any  of the  interior  operate The  FOPS and  flow f i e l d .  The  the  solve  finite-difWhile  dif-  to solve  the  finite-element  t h e FREESURF1 p r o g r a m s . models i s a f i e l d  p o i n t s of a g r i d  output  can  superim-  By means of D a r c y ' s l a w , i n f l o w and  outflow along  By means of E q u a t i o n  of  be c o n t o u r e d  f l o w n e t , or the v e l o c i t y  point.  2)  examples of  used t o  the  e l e m e n t method.  from the m a t h e m a t i c a l  c a l c u l a t e t h e amount o f  boundaries  i f flow r a -  (1970).  techniques  directly.  used to c o n s t r u c t flow n e t s . can  face  different materials,  Witherspoon  head v a l u e s a t the n o d a l the  seepage  s o l v e d w i t h FREESURF1  techniques  flow equation  method i s u t i l i z e d The  free sur-  characteristics,  b a c k g r o u n d m a t e r i a l and  most common n u m e r i c a l  f e r e n c e m e t h o d and  groundwater  e)  flow  boundary v a l u e problems i n hydrogeology are  ferent  condi-  f r e e s u r f a c e becomes d i s c o n -  i n t e r f a c e b e t w e e n two  i s d i r e c t e d t o Neuman and  The  of t h e  three dimensional  k i n d s of p r o b l e m s t h a t can  reader  one  specified hydraulic  In a d d i t i o n to these 1)  g i v e n any  symmetry a b o u t t h e v e r t i c a l c o o r d i n a t e , and  t i n u o u s a c r o s s an i n an  be  t h e u p p e r b o u n d a r y , and  the upper boundary.  FREESURF1 can  as  i n or out  can  These boundary  i m p e r m e a b l e , b) c o n s t a n t  head, c) c o n s t a n t  on  the boundaries  of t h e  3.6,  one  and one  the  flow  at  can c a l c u -  95  late  the f l u i d The  ysis. and  p r e s s u r e s a t any p o i n t  FOPS model was  The  free surface  the h y d r a u l i c  used  f o r an  was  i n the  initial  system. sensitivity  s e t as a c o n s t a n t head  conductivity  field,  e f f e c t s on t h e t o t a l d i s c h a r g e  FREESURF1 model was sible  boundary,  the d e p t h - o f - f l o w  a n d t h e e l e v a t i o n o f t h e w a t e r t a b l e were v a r i e d their  leaving  the system.  then u t i l i z e d to simulate  on t h e g r o u n d w a t e r  s y s t e m was  varied  regime.  The  various  recharge rate  The  pos-  and  f o r each h y d r o g e o l o g i c environment  ine the water t a b l e c o n f i g u r a t i o n  field  to observe  h y d r o g e o l o g i c e n v i r o n m e n t s a t Meager M o u n t a i n  effect  anal-  their  into  the  t o exam-  and amount o f d i s c h a r g e i t  produced. Before discussing boundary must be  the r e s u l t s of the m o d e l l i n g ,  value problems  we w i s h t o s o l v e  the  models,  defined.  Simulation  Region of The  using  the  Strategy  Flow region  of flow  f o r t h e Meager M o u n t a i n  groundwater  simulations  i s a two-dimensional v e r t i c a l cross-section  as  illustrated  in Figure  the  l i n e A-B The  i n Figure  7.1.  7.2  The  through d r i l l  l o w e r end o f t h e s e c t i o n  while  the upper  Mountain.  The  end upper  s e c t i o n was  boundary  h o l e s M5-78D and M7-79D.  i s the centre  i s a t the h i g h e s t  taken along  point  i s the ground  o f Meager of  Creek  Capricorn  surface  and  the  96  metres  F i g u r e 7.1  Region of flow f o r mathematical  modelling.  >  4  F i g u r e 7.2  f  \LOC*TION  W*P  L i n e of s e c t i o n taken f o r c r o s s - s e c t i o n i n F i g u r e 7.1.  97  lower boundary f o r the FREESURF1 s i m u l a t i o n s t r a r i l y at -2000 m e l e v a t i o n . FOPS s i m u l a t i o n s tivity  v a r i e d from -305  analysis.  unit thickness  The  The  chosen a r b i -  lower boundary f o r m to -915  cross-section  perpendicular  was  m f o r the  i s considered  the sensi-  to have a  to the page.  Equation of Flow The  equation f o r s a t u r a t e d ,  two-dimensional, steady-  s t a t e flow through heterogeneous, a n i s o t r o p i c m a t e r i a l i s :  3 3x  K „ ( x , z)  where x and and  K  z  are  5h 3x  K (x,z) z  8 z  the h o r i z o n t a l and  Assigning  -<*v  (X,2)  v e r t i c a l coordinates,  v e r t i c a l components of the  conductivity  K=K  (7.1)  —  z are the h o r i z o n t a l and  sotropic hydraulic head.  +  and  tensor K  =K z  X  and  h i s the  (X,Z),  K  x  ani-  hydraulic  identifies  the  z  c o n d u c t i v i t y d i s t r i b u t i o n as hetergeneous. The  s o l u t i o n of Equation 7.1  h(x,z) in the  Boundary The  i s the h y d r a u l i c  head  field  cross-section.  Conditions boundaries BC,  meable while AEFB i s the  CD  of F i g u r e  water t a b l e .  |^- = 0 on BC and 8 x  and DA  AD  7.1  are  inter-  In mathematical terms (7.2)  and |^ = 0 on d  Z  CD  (7.3)  98  On AE, t h e h y d r a u l i c Meager Creek because in  the valley  fill  H=Z where Z  r  The the  r  head  i s equal t o t h e e l e v a t i o n of  t h e water t a b l e  deposits,  i s very near t h e surface  therefore,  on AE  (7.4)  i s t h e e l e v a t i o n o f Meager  Creek.  w a t e r t a b l e EFB i s t r e a t e d  i n two ways.  FOPS p r o g r a m  for the s e n s i t i v i t y  specified at a l lpoints  analysis  When  t h e heads a r e  on t h e w a t e r t a b l e s u c h  that  H=z on EFB  (7.5)  and t h e p r o b l e m c a n be s o l v e d using  t h e FREESURF1 p r o g r a m  seepage  directly.  The a p p r o a c h when  i s t o s p e c i f y t h e heads  on t h e  f a c e , EF: H=z on EF  (7.6)  where z i s t h e water t a b l e e l e v a t i o n and t h e l a n d elevation. the  using  On t h e f r e e s u r f a c e  rate of inflow  I i s defined  portion  surface  o f t h e w a t e r t a b l e FB  so t h a t  K ( x , z ) U l = I On FB  (7.7)  dz  that  i s , t h e water t a b l e p o s i t i o n i s not s p e c i f i e d but de-  p e n d s on t h e amount o f p r e c i p i t a t i o n water system. is  necessary.  infiltrating  Under t h e s e c o n d i t i o n s ,  t h e ground-  an i t e r a t i v e  solution  99  Hydraulic  Conductivity  The  Distribution  v a r i a b l e c o n d u c t i v i t i e s of  e n v i r o n m e n t were d i s c u s s e d Figure  6.6.  geology  Due  i n the  configurations c a s e and  the  the  Meager a r e a ,  of  p r e s e n t s the  lying  used.  information  a n a l y s i s only  The  illustrated  on  i s assumed t o be  the  the  in subsurface  geological  the  simplest  layer  and  7.3.  performed  Figure The  with  7.3(a) r e -  entire  Figure  system w i t h  zone.  and  d)  cross-  7.3(b) i n -  flow  conductivities, anisotropies, s y s t e m were v a r i e d  tempt to d e f i n e  the  hydrogeological  environment.  7.3(d) the includes  The  1 5  7.7  occurs and  f r o m run  over-  most com-  a  volcanic  designated  (10"  in Figures  insignificant  volcanics  i s simulated  conductivity lines  the  Figure  simulated  a fault  hydraulic  zone but  v a l u e s f o r the  iso-  idealized geological  geology.  Finally,  7.3(b  Therefore, equipotential into this  four  in Figure  configuration  in Figure  a r e a a v e r y low  homogeneous  zone t h r o u g h t t o e x i s t b e l o w Meager C r e e k .  layer, granodiorite meable a r e a  the  granodiorite.  granodiorite.  geological  the  main s i m u l a t i o n s  possible  7 . 3 ( c ) i s a two  The  depicted  were m o d e l l e d , b e g i n n i n g w i t h  simplest  cludes a fault Figure  geologic  a number of p o t e n t i a l  FREESURF1 p r o g r a m u t i l i z e d  configurations  plex  i n C h a p t e r 6 and  lack  sensitivity  c a s e was  section  idealized  w o r k i n g t o t h e most c o m p l e x .  For tropic  to the  the  by  imper-  giving  the  m/s). t o 7.11  extend  there.  recharge t o run  rate  i n an  at-  f e a s i b l e range of p a r a m e t e r s f o r each Feasibility  i s defined  i n terms  o o •paq.BTnuiTs  i -'  suoTq.ean6"pguoo x e o x B o i o a o  £'L  ajnbTj-  0 ' r ','  ^ A A A A A A A A A A A A A A A A A A A A A \ A A A A A A A A A A A A A A A A A A A A " L A A A A A A A A A A A A A A A A A A A ^ A A A A A A A A A A A A A A A A A i A A A A A A A A A A A A i A A A A A A A A A l A A A A A A A k A A A * ft  A  A A A A A A A A A A A A A A A A A A A A A A A A A A A A " ft »  A A A A A A A A A A A A A A A A A A  A A A A A A " A A A A A A '  t0|Ut3|0A  A A A A A A £_A  A A A A  A A A A  A A A A A  A A A A A  A A A A A  A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A| A  A A A A A A  •l|JO|pou*JO  3 jjnseejj  L jjnseejj  101  of  the  in  this  flow  report  The in  the  systems t h a t on  the  basis  unconsolidated  model.  deposits  The  f i t the  of  the  hydraulic  available field  conductivity  the  tion  i n the  fill  from the  system i n the  rock.  the  rock  included  valley  hydraulic  conductivity  i t t r a v e l s down g r a d i e n t  the  s t r e a m as  illustrated  thematical  models used are  w a t e r movement i n t h e  two  dimensional.  valley f i l l  the  dischar-  distributhe  i n the  in Figure  fill  There-  amount o f w a t e r  F u r t h e r m o r e , when w a t e r e n t e r s  r e c t i o n as  the  of  not  basement or v o l c a n i c s .  f o r e , t h e • c o n t r o l l i n g f a c t o r f o r the from the  was  data.  o r d e r s of m a g n i t u d e l a r g e r t h a n  c n d u c t i v i t y of  ging  c a l u l a t i o n s presented  Quaternary m a t e r i a l  i s a number o f  hydraulic  best  valley  same d i -  7.4.  The  ma-  Consequently,  c a n n o t be  modelled.  F i n i t e Element Method The  finite  e l e m e n t method w o r k s on  c o m p l e x f u n c t i o n can number of The  simpler  of ly.  the  heads at  e l e m e n t can the  reader  The be  the  FOPS and  this  and  calculated  of  The  the  hydraulic function  mathematical-  thesis to discuss  Gray  finite  c o r n e r s of  solution in detail.  i s r e f e r r e d to Pinder  For  be  a  subregions.  unknown f u n c t i o n  can  s c o p e of  method of  the  a  e x p r e s s e d as a l i n e a r  n o d e s and  I t i s beyond the  finite-element  over small  c a l l e d e l e m e n t s and  c a l l e d nodes.  h e a d w i t h i n an  premise that  a p p r o x i m a t e d p i e c e w i s e by  linear functions  subregions are  elements are  be  the  the  interested  (1977).  FREESURF1 p r o g r a m s u s e d h e r e a d i f -  102  F i g u r e 7.4  Movement o f g r o u n d w a t e r i n t h e b a s e m e n t r o c k valley f i l l .  and  103  ferent  K  and  x  K  Head v a l u e s a r e boundary. fied  v a l u e can  z  Recharge r a t e or t o t a l  are  The  h a n d l e d by  finite  the  can  be  and  total  values  drawn by  Input  the  into a hydraulic hand l a t e r ,  both programs the of  dinates,  n o d a l numbers and  the  the  one  of  the  vertical  each of  the  In the the  finite  program.  i s the h y d r a u l i c  head  i n both programs con-  head p a t t e r n  i f necessary.  input  The  and  a flow  recharge  e l e m e n t s on  data required  the  net  rate  upper  and  i n the  FOPS p r o g r a m t h e  by  the  for a given  the  the  de-  coor-  geological  flux  7.3,  conductivity  and  3)  values  for  configuration. water t a b l e p o s i t i o n i s  The  configuration  p o s i t i o n of  the  discharge  are  Conversely,  i n t o the  defined  water t a b l e  steady-state  water t a b l e p o s i t i o n chosen.  p r o g r a m m e r and  in Figure  f l u x e s a c r o s s the  program.  FREESURF1 p r o g r a m , t h e  a  e l e m e n t number s p e c i f i c a t i o n s , 2)  horizontal hydraulic  formations  i s , 1)  e l e m e n t mesh i n c l u d i n g n o d a l  geological configurations  programmer and  calculated  the  of t h e  automatically.  finition  lues,  speci-  Data For  by  head  I m p e r m e a b l e boun-  i n t e r n a l operations  A p l o t t i n g routine  calculated  a constant  a f l u x boundary.  d i s c h a r g e of water f o r the  boundary are  f o r each element.  discharge r a t e s are  element s o l u t i o n output  v a l u e a t e a c h node. tours  designated  s p e c i f i e d a t e a c h node on  f o r e a c h e l e m e n t on  daries  be  va-  dependent in  on  the  system i s d e f i n e d  water t a b l e  are  by  the  is calculated  104  by  the program.  given rate  The s t e a d y - s t a t e  water t a b l e p o s i t i o n f o r a  g e o l o g i c c o n f i g u r a t i o n i s d e p e n d e n t on t h e  recharge  chosen. W i t h an u n d e r s t a n d i n g  of the s i m u l a t i o n s t r a t e g y a t  hand, t h e r e s u l t s of t h e m a t h e m a t i c a l m o d e l l i n g  c a n now be  di scussed.  Sensitivity  Analyses  w i t h FOPS  I n C h a p t e r 6, t h e amount o f g r o u n d w a t e r d i s c h a r g e t h e Meager C r e e k b a s i n was c a l c u l a t e d . discharge terial, The  The amount o f t o t a l  d e p e n d s on t h e h y d r a u l i c c o n d u c t i v i t y o f t h e ma-  t h e water t a b l e e l e v a t i o n , and t h e d e p t h of f l o w .  p r o g r a m FOPS was u s e d t o d e t e r m i n e t h e e f f e c t  m e t e r s have on t h e t o t a l parameter has l i t t l e ignored  discharge.  effect  thereby  resulting  range f o r t h e o t h e r Figure  input  on t h e t o t a l  discharge  para-  i t c a n be  i n t h e FREESURF1 s i m u -  i n a narrowing  of the p o s s i b l e  parameters.  7.5 i l l u s t r a t e s t h e f o u r d i f f e r e n t  u s e d f o r t h e FOPS s i m u l a t i o n s . 5500 m l o n g e x t e n d i n g  these  I f i t i s found t h a t a  as a v a r i a b l e input parameter  lations,  geometries  FOPS1 r e p r e s e n t s  a flow  f r o m -305 m (-1000 f t ) t o 1525 m  f t ) on i t s r i g h t  side.  towards the l e f t  t o a minimum o f 425 m.  field  out of  field (5000  The w a t e r t a b l e d e c r e a s e s i n h e i g h t  was d e e p e n e d 610 m w h i l e  I n FOPS2 t h e f l o w  i n FOPS3 a n d FOPS4 t h e w a t e r  t a b l e was r a i s e d a b o v e a n d l o w e r e d b e l o w t h e FOPS2 p o s i t i o n . Hydraulic  c o n d u c t i v i t y values  of 1 0 " , 10* 7  8  a n d 1 0 ' ' m/s  Table Summary o f S e n s i t i v i t y Geometric Type  7.1 Analysis Simulations  Hydraulic T o t a l Discharge C o n d u c t i v i t y (m/s) (nl3/s/n\)  Maximum Water T a b l e E l e v a t i o n (m)  Depth o f Flow(m)  1525  -305  7  1525  -305  FOP SI  lxlO  - 7  9.44xl0  FOP SI  lxlO  - 8  9.44xl0~  F0PS1  lxlO  - 9  9.44xl0  - 8  1525  -305  F0PS2  lxlO  - 7  1.15xl0  _ 5  1525  -915  FOPS 2  lxlO"  6  1525  -915  - 7  1525  -915  FOPS 2  8  -9 1x10  FOPS 3  lxlO  - 7  FOP S3  lxl(f  8  -9  - 6  1.15xl0~ 1.15xl0  1.71xl0"  5  1830  -915  1.71xl0"  6  1830  -915  1.71xl0~  7  1830  -915  FOP S3  1x10  F0PS4  lxlO  - 7  8.50xl0~  6  1220  -915  F0PS4  lxlO  - 8  8.50xl0~  7  1220  -915  8.50xl0~  8  1220  -915  FOPS 4  -9 1x10  107  where s i m u l a t e d w i t h e a c h g e o m e t r y . charge  any g i v e n geometry  conductivity  the outflow varies d i r e c t l y  of t h e m a t e r i a l .  d u c t i v i t y an o r d e r o f m a g n i t u d e , discharge For flow  flow  with  I f one i n c r e a s e s t h e c o n t h e n t h e amount o f t o t a l  a given h y d r a u l i c c o n d u c t i v i t y value, deepening the 610 m a s i n g e o m e t r i c t y p e FOPS2 i n c r e a s e s t h e  d i s c h a r g e 1.22 t i m e s . field  T h i s i n d i c a t e s t h a t a v e r y deep  w o u l d n o t have a s u b s t a n t i a l l y  charge than a s i m i l a r  greater t o t a l  dis-  but s h a l l o w e r system.  When t h e w a t e r t a b l e e l e v a t i o n 1525  dis-  i n c r e a s e s by an o r d e r o f m a g n i t u d e .  field  total  total  i s s u m m a r i z e d i n T a b l e 7.1.  For the  The r e s u l t i n g  i s i n c r e a s e d 305 m f r o m  t o 1830 m t h e t o t a l d i s c h a r g e i n c r e a s e s by 1.5 t i m e s .  When t h e w a t e r t a b l e e l e v a t i o n 1220  i s l o w e r e d 305 m f r o m 1525 t o  m the t o t a l  d i s c h a r g e d e c r e a s e s by 0.5 t i m e s .  the water  t a b l e must be r a i s e d o r l o w e r e d o v e r  fore,  Therelarge  e l e v a t i o n changes i n o r d e r t o cause a s u b s t a n t i a l change i n the  total It  system is  i sclear  then, that the t o t a l  d i s c h a r g e from t h e f l o w  i s very s e n s i t i v e t o h y d r a u l i c c o n d u c t i v i t y v a l u e s but  reasonably i n s e n s i t i v e  pecially the  d i s c h a r g e from t h e system.  insensitive  t o water t a b l e v a r i a t i o n s , and e s -  t o the depth of flow.  f o l l o w i n g FREESURF1 s i m u l a t i o n  results,  Accordingly, in the hydraulic  c o n d u c t i v i t i e s and t h e water t a b l e p o s i t i o n s w i l l but t h e d e p t h of f l o w  i s chosen a r b i t r a r i l y  be v a r i e d  and remains  cons-  108  tant.  FREESURF1  Variable  Parameters  The outflow  two  p a r a m e t e r s i n D a r c y ' s law  Q are  gradient lic  the  .  hydraulic  The  head f i e l d ,  head f i e l d in  and  i n t o the  i n the  d e p e n d s on  geologic  K will  the  determine the  is  i n the  river  flow  we  (1.13  over the  will  m /s) 3  of  We  will  u n i t s of The or  the  assume t h a t  t o the  designate  of t h e  the  the  which  recharge  rate  variables I  system.  above the  surface 45%  of the  total  f l u x per  a r e a of  of t h e  from t h i s valley.  a thickness  total  this  report  the  total  of 1 m,  discharge  the  basin;  groundwater  side. The  of  stage l o c a t i o n  Meager M o u n t a i n s i d e o f  i s contributed  18,500 m l e n g t h  contribution  hydrau-  water t a b l e  c o m b i n a t i o n of  The  3  c r o s s - s e c t i o n m o d e l has  the  determined that the c o n t r i b u t i o n  m /s.  c o n s t i t u t e s 45%  the  hydraulic  in this  i n f l o w I or  i n t h e Meager b a s i n  r a n g e 2.5  therefore  p o s i t i o n of t h e  The  the  d e p e n d on  system modelled  f l u x Q out  I n C h a p t e r 6 i t was groundwater flow  gradients  t h e amount o f system.  that determine  c o n d u c t i v i t y K and  hydraulic  t u r n d e p e n d s on  and  Modelling  It  enters  two-dimensional consequently i t s  i s 6x10"  u n i t l e n g t h a s q;  5  m /s/m. 3  it  has  m /s. 2  r e c h a r g e r a t e was  1.14x10"  8  m/s.  The  estimated  p r e v i o u s l y a t 0.36  above e s t i m a t e d  values  of  I and  m/y q  109  allow  f o r t h e c a l c u l a t i o n of d i f f e r e n t  conductivity d i s t r i b u t i o n s using  feasible  hydraulic  FREESURF1.  F i n i t e E l e m e n t Mesh The tions  f i n i t e e l e m e n t mesh u s e d f o r t h e FREESURF1  is illustrated  simplified The  in Figure  v e r s i o n of  They can  flex  water t a b l e to r i s e or  t h e g e o l o g y by F a i r b a n k  upwards and lower  i n t e n t i o n of t h e a u t h o r  in Figure all  I t i s s u p e r i m p o e d on  q u a d r i l a t e r a l e l e m e n t s a b o v e 600  pible.  The  7.6.  the  7.6,  volcanic  this will The table  the  mapping and  p r o g r a m a l s o has  i n i t s exact  s y s t e m but  holes  be  i t is felt  have n e g l i g i b l e e f f e c t  on  For  the  the  volcanics  this  indicate.  limitations  slightly  collas-  limitation  The  situating i s an  simulated  the  extensive that  simulations. the  water ground  p o s i t i o n of discharge  t h a t the p o s s i b l e e r r o r s field.  to  reason  irregular  i n e r r o r at the  flow  as  that  It is felt  i n a c c u r a c i e s i n the  simulations.  (1979).  position.  (d) a r e more  l o c a t i o n when t h e r e  i n these  t h e w a t e r t a b l e may  7 . 3 ( c ) and  drill  the  a  p a r t of t h e mesh have  same h y d r a u l i c c o n d u c t i v i t y .  cause o n l y minor  s u r f a c e as  of the  to simulate  however t h e p r o g r a m has  layers in Figure  than f i e l d  m e l e v a t i o n are  steady-state  elements i n the c o l l a p s i b l e  possess the  et a l .  downwards t o a l l o w  to the was  simula-  will  end  G d - Granodiorite  metres  Figure 7.6  F i n i t e element mesh used i n FREESURF1 s i m u l a t i o n s .  i—• o  Ill  Results For  the  simulations  t i o n s were s e l e c t e d the  s y s t e m was  as  hydraulic  i n T a b l e 7.2.  varied until  table configuration draulic  the  the  as  in Figure  of node 252 (Figure  i n the  7.7(a).  The  Node 252  minimum w a t e r  7.7  intersects  minimum o c c u r s when t h e e l e v a t i o n of  last  node t h a t  the  When node 252  the  i s too  low  peaks  271  i s moveable. elevation  moves l o w e r t h a n 271  water t a b l e e l e v a t i o n  The  elevation  node  i s set a t a c o n s t a n t head e q u a l t o the  Meager C r e e k .  hy-  t o 7.11.  v a l l e y s between mountain  i s the  into  r e s u l t i n g contoured  water t a b l e  highland  distribu-  recharge rate  in Figures  becomes l e s s t h a n t h e  7.6).  Node 271  cates  The  head f i e l d s a r e d e p i c t e d  ground surface  The  maximum and  were f o u n d .  maximum v a l u e o c c u r s when t h e  conductivity  t o be  of  i t indiphysically  r e a l i st i c . The  lines  in Figures  equal hydraulic isotropic  sarily  For  lines the  the  charge areas. as  per  lines.  drawn p e r p e n d i c u l a r a flow  net  as  in  a n i s o t r o p i c cases f l o w l i n e s are t o the  equipotential  diagrams d i r e c t l y .  diagrams i n d i c a t e the  daries  be  methods f o r d r a w i n g the  drawn on  which j o i n p o i n t s  equipotential  to construct  perpendicular  graphic  t o 7.11  called  c a s e s f l o w l i n e s can  equipotential 7.7(b).  head are  7.7  The  f l o w l i n e s but The  R/D  7.3.  The  show t h e hydraulic  For to  the the  Figure not  neces-  There  are  they cannot  designations  boundary between the  dashed l i n e s  Figure  lines.  of  on  r e c h a r g e and  geological  be the  dis-  boun-  c o n d u c t i v i t i e s used  Table Hydraulic  Geological Configuration (as i n F i g . 7.3)  K K K K  g  Conductivity  Simulation Designation  FREESURF 1  A  Kg=10  B  K  FREESURF 1  Cl  K =10"  FREESURF 1  C2  K  FREESURF 2  A  K =10  FREESURF 2  B  K  FREESURF 3  A  K =10  FREESURF 3  B  K =5xl0  FREESURF 4  A  K =5xl0~  FREESURF 4  B  K =5xl0  g x  =10  _ 7  g x  g x  8  K =10"  7  g z  =5xl(f - 8  g  g x  K =10"  K =5xl0  9  f  =5xl0  K =  K =10  8  f  v  8  Kf=10  _ 7  - 8  K =10  _ 7  v  f  g z  =  i n the v e r t i c a l  area.  K  K  g 2  K, = 1 0 g  =5xl0 - 8  K  b  gz  gx  gz  = 1 0 K  gx  g z  =10K  direction.  direction.  g z  Kh=10 g z  g  g x  & Kf=2K  _ 1 5  =5xl0  v  g x  Kf=10K =2K  v  Kg =K =10K  gx  g  _ 8  Z  v  g z  g  K =K =10K  _ 8  K, = 5 x l 0 " ^ K g x  gz  = 1 0 K  v  _ 9  g x  v  K  1 0 K  K =10K  K =5xl0  i n the h o r i z o n t a l  = c o n d u c t i v i t y o f t h e impermeable  K =10  _ 1 5  _ 8  = c o n d u c t i v i t y o f the g r a n o d i o r i t e , conductivity of the granodiorite  7  g  _ 8  gx~  Kf=10K  b  g z  K =10  _ 7  •15  K =5xl0  _ 9  g x  b  7  K  -8  g z  K =l(T  v  = c o n d u c t i v i t y o f the v o l c a n i c s .  Dimensionless Ratios  g z  8  = c o n d u c t i v i t y of the granodiorite  v  Distributions  Conductivity D i s t r i b u t i o n (m/s)  FREESURF 1  Kf = c o n d u c t i v i t y o f t h e f a u l t . K  7.2  & K =2K f  g z  E q u i p o t e n t i a l p a t t e r n f o r FREESURF I A a n d FREESURF I B c a s e s .  Figure  7.8  Equipotential  pattern  for  FREESURF  IC  cases.  118  for  each g e o l o g i c  u n i t c a n be g l e a n e d f r o m T a b l e 7.2  r e l a t i v e h o r i z o n t a l and v e r t i c a l  hydraulic  illustrated  diagrams.  on t h e e q u i p o t e n t i a l  while  c o n d u c t i v i t i e s are  C a s e I A i s homogeneous a n d i s o t r o p i c ; c a s e s I B a n d I C are  homogeneous and a n i s o t r o p i c .  three  cases i l l u s t r a t e s  field  c a u s e d by a n i s t r o p y .  IB t h a t  the flow  horizontal tivity is  field  anistropy.  than v e r t i c a l  A c o m p a r i s i o n of these  t h e changes i n the e q u i p o t e n t i a l N o t e i n t h e d i a g r a m s o f FREESURF  becomes d i s t o r t e d due t o a  greater  A larger horizontal hydraulic  conduc-  i s u n r e a l i s t i c f o r t h e basement r o c k b u t  shown h e r e t o d i s p l a y t h e c h a n g e s i n t h e e q u i p o t e n t i a l  field  c a u s e d by  anisotropy.  I n t h e 1C1 v s 1C2 c a s e s t h e h y d r a u l i c  conductivity i s  changed but t h e r a t i o between t h e h o r i z o n t a l and v e r t i c a l hydraulic  c o n d u c t i v i t y , K =K  in Figure  7.8 t h a t  is nearly  identical.  X  tween t h e v a r i o u s  Z  r e m a i n s c o n s t a n t a t 1:10.  the h y d r a u l i c  head f i e l d  T h e r e f o r e , as long  hydraulic  t a n t and t h e r e c h a r g e r a t e  conductivity i s increased  Note  i n t h e two c a s e s  as t h e r a t i o s bev a l u e s remains conso r d e c r e a s e d t h e same  amount a s t h e c o n d u c t i v i t i e s , t h e f l o w p a t t e r n  w i l l not  change. FREESURF in  2 displays  t h e e f f e c t o f a more p e r m e a b l e  t h e s y s t e m a t shown i n F i g u r e  net  i n Figure  the  surface  thetical  7.3  ( b ) . The p a r t i a l  7.9(b) shows how t h e f a u l t a c t s  for fluids  that  fault flow  as a highway t o  i n t e r s e c t the zone.  I f t h e hypo-  f a u l t d o e s e x i s t i t w o u l d become t i g h t e r a n d much  119  l e s s c o n d u c t i v e at depth, analogous to f a u l t s discussed  in  Chapter 5 s t u d i e d  sys-  by Raven and  tems h a v e c l a y seams o r  a v e r y low  (1977).  Most f a u l t  s l i c k e n s i d e s t h a t a c t a s an  meable boundary f o r f l u i d s given  Gale  so t h e  conductivity  a r e a below the  to simulate  this  imper-  fault  is  impermeable  boundary. Figure patterns rock.  7 . 1 0 ( a and  for  b)  are  the  isotropic volcanics  Recall  f r o m D a r c y ' s law the  lic  gradient  .  and  basement r o c k i s s i m i l a r but  The  over  that  r o c k d e p e n d s on  i s one  hydraulic  FREESURF 3A  equipotential  i s o t r o p i c basement  the  discharge through  c o n d u c t i v i t y K and  hydraulic  gradient the  i n the  hydraulic  o r d e r of magnitude l a r g e r i n t h e  the  hydrau-  volcanics  conductivity  volcanics  than i n  basement r o c k .  T h e r e f o r e , most of t h e  flux will  the  As  s i t u a t i o n would  volcanics.  stated  to year round s p r i n g few  earlier  l i n e s at the  e x i s t a t Meager M o u n t a i n .  s e n t s a more l i k e l y rock having the isotropic  valent  using  basal  Figure  s i t u a t i o n with  conductivity  the  the  isotropic hydraulic  conductivity, K  c o n d u c t i v i t y , and  ductivity  of  the  1.58x10"  or  3 t i m e s l e s s than t h a t of  small  8  z  basement r o c k .  d i f f e r e n c e would not  from the  K  volcanics  i n t o the  i s the This  basement  equivalent  x  i s the  i s the  vertical  be  equi-  horizontal  hydraulic  con-  value c a l c u l a t e s to the  volcanics.  substantially restrict basement.  and  basement r o c k can  z  hydraulic  lead  repre-  and  The  f o r m u l a K =\|K K , where K x  d)  volcanics  the  through  contact  7 . 1 0 ( c and  the  of  be  volcanic  same v e r t i c a l c o n d u c t i v i t y .  hydraulic  calculated  this  the  the  be  This flow  120  Figures  7.11  (a and  t e n t i a l patterns  is  i n the  The  of  the  fault  fault exists. and  d)  The  the  and  few  The  of  are  the  and  of  of  the  and  the  volcanics hydraulic  the  basement.  l i n e s at  in Figure  where i s o t r o p i c  the  the  the  most r e a l i s t i c ,  an  v e r t i c a l hydraulic  horizontal conductivity granodiorite  base-  occur.  equipotential patterns situation  the  the  would cause s p r i n g  basement g r a n o d i o r i t e  the  times that  a n i s o t r o p i c basement r o c k s w i t h  meable f a u l t zone.  equipo-  isotropic  of  basement and  simulations  r e p r e s e n t the  overlie  over  conductivity  i s 10  volcanic-basement contact, FREESURF 4B  volcanics  than the  Again, t h i s configuration  The  FREESURF 4A  basement r o c k e x t e n d i n g t o w a r d s  hydraulic  f i v e times greater  conductivity  r e p r e s e n t the  for isotropic  ment w i t h a f a u l t Meager v a l l e y .  b)  volcanics  volcanics  if a  7.11(c  volcanics  isotropic  per-  conductivity i s the  i s greater  of  same.  The  than  that  most p e r m e a b l e zone i s t h e  fault  area. The  fluid  p r e s s u r e P i s r e l a t e d to the  shown i n E q u a t i o n 3.6. i n the  p r e s s u r e a t any  e q u i p o t e n t i a l diagrams i n Figures  calculated.  Figure  graphs f o r the vetically as  T h e r e f o r e , the  7.12  various  and  the  l i n e A-B  chosen because i t i s the been d r i l l e d .  In t h e  are  simulations.  downward b e l o w t h e  shown by  7.13  p r e s s u r e head  7.7  t o 7.11  p r e s s u r e vs The  This  be  depth  v a l u e s where  7.7(d).  point  can  unconsolidated-bedrock  in Figure  as  taken  contact  position  a r e a where a number o f h o l e s  minumum w a t e r t a b l e e l e v a t i o n  was  have  examples,  121  PRESSURE,  Figure  7.12  Pa  P r e s s u r e v s d e p t h g r a p h o f minimum table elevation examples.  water  122  PRESSURE,  F i g u r e 7.13  Pa  P r e s s u r e v s d e p t h g r a p h o f maximum w a t e r e l e v a t i o n examples.  table  123  the  bottom hole p r e s s u r e v a r i e s w i t h i n  of h y d r o s t a t i c  pressure.  plus  o r m i n u s 500 Pa  I n t h e maximum w a t e r t a b l e  eleva-  t i o n examples, the bottom hole p r e s s u r e v a r i e s w i t h i n p l u s or m i n u s 900 Pa o f i s o s t a t i c the  pressure only  pressure.  varies within.5  s u r e i n any o f t h e g e o l o g i c The  graphs i n Figures  I n o t h e r w o r d s , a t 900 m t o 10% of i s o s t a t i c  configurations  modelled.  7.7 t o 7.11 c a n be c o n s i d e r e d  m e n s i o n l e s s i f the r a t i o s of the d i f f e r e n t h y d r a u l i c tivity  d i s t r i b u t i o n s remain c o n s t a n t .  case simulated if  are tabulated  the hydraulic  pres-  di-  conduc-  The r a t i o s f o r e a c h  i n T a b l e 7.2.  In other.words,  c o n d u c t i v i t i e s are doubled the recharge  rate  must be d o u b l e d t o a t t a i n t h e same w a t e r t a b l e e l e v a t i o n s a n d equipotential pattern.  The c o n s e q u e n c e o f t h i s ,  i s that  the t o t a l  discharge also  Of  the three  v a r i a b l e parameters, hydraulic  ty,  r e c h a r g e r a t e , and t o t a l  i s t h e most a c c u r a t e l y m /s.  The t o t a l  2  of c o u r s e ,  doubles.  discharge,  the t o t a l  estimated at approximately  d i s c h a r g e of t h e o r i g i n a l  conductividischarge 6x10'  simulations  5  c a n be  m u l t i p l i e d by a f a c t o r t o p r o d u c e a t o t a l d i s c h a r g e o f 6 x 1 0 " m /s. 2  To k e e p t h e same w a t e r t a b l e c o n f i g u r a t i o n  f o r each  g r a p h t h e c o n d u c t i v i t i e s a n d r e c h a r g e r a t e must a l s o be m u l tiplied  by t h e same f a c t o r . - The e n d r e s u l t i s s u m m a r i z e d i n  T a b l e 7.3. discharge, and  The t a b l e  i l l u s t r a t e s that with  the set t o t a l  t h e r e c h a r g e r a t e n e e d e d v a r i e s b e t w e e n 1.09x10""  1.81x10"'* o r 14 a n d 2 3 % o f t h e t o t a l p r e c i p i t a t i o n .  w a t e r b a l a n c e c a l c u l a t i o n s o f C h a p t e r 4 and e s t i m a t e s o f  The  5  Table Influx  Type  7.3  and H y d r a u l i c C o n d u c t i v i t y Total Discharge (mVs/m)  Recharge Rate (m/s) •8  IA Max Flux  1.77x10  IA Min F l u x  1.09x10"  D i s t r i b u t i o n s with a Set  •5  6x10  Conductivity  22.3  K =l.52x10  -7  13.8  g  -5  1B Max Flux  1.76xl0~  6x10  1B Min F l u x  1.09xl0~  6x10  1C Max Flux  1.76xl0~  6xl0~  1C Min Flux  l.Olxlo"  1C Max Flux  1.81x10"  6x10" 6x10 -5  -5  K gx~2. .78x10"  =2.78x10  K g =4..23x10"  K  K gx= ' .94x10" K; = 6 .,91x10"  K  X  5  12.7  22.5  22.8  9 2  1.78x10" -8 1.09x10  6x10 -5 6x10 -5  K =7.41xl0 K =7.41xl0  6xl0~-5 6x10 -5  K =9.84x10 r  •5  22.2  6  2 Max(iso)  1.79x10* -8 1.11x10  13.8  g z =6.91x10" ,15x10" 8„ =6.15x10 K ;gx= ' 8 K, - 7 . .32x10" =7.32x10" g gx  6xl0~  2 Min(aniso)  22.2  g z =4.23x10" -7 =5.94x10  1.10xl0~  2 Max(aniso)  -8  !  1C Min F l u x  2 Min(iso)  % Total Precipitation  (m/s)  K =9.12x10  •5  6x10  Outflux  g x  K  _ 7  f  g  _ 8  K =1.04xl0~ K  =1.04xl0~ -7 K„ =4.92x10 -8„ K„,=4.92x10 g -8 9z K = 4 . 92x10  6  f  13.9  Z  f  K =9.02x10  7  gz  f  13.8 22.6 14.0 22.3  3 Max(iso,gran)  1.77x10"  6x10'  3 Min(iso,gran)  1.09xl0~  6x10'  3 Max(aniso gran)  1.77x10  6x10'  3 M i n ( a n i s o gran)  1.09x10"  6x10"  4 Max(iso)  1.76x10"  6x10"  K =l.36xl0" K =2.71xl0" K =2.71xl0~  22.2  1.09xl0~ -8 1.77x10  6x10" 6x10 -5  K =2.22xl0 Kf=4.44xl0 Kg=4.44xl0"  13.8  -8  -5  4 Min(iso) 4 Max(aniso)  K =1.62xl0" K =1.62xl0 7  v  -5  - 8  g  K =2.99xl0" Kg=2.99xl0" 7  13.8  8  v  •5  K =1.63xl0" K  g x  =1.63xl0"  K =2.71xl0" K  g x  =2.71xl0"  7  v  •5  7  v  7  v  v  7  f  _7  =1.63x10  6  ^gz K =2.71x10 gz  g  _7  8  K =1.42xl0" K =2.83xl0" Kg =1.42xl0" 7  v  f  7  X  22.3  gz  1.10x10  6x10  K =2.24xl0~ Kf=4.48xl0" v  7  K =1.42xl0 g z  Kg = C o n d u c t i v i t y of the  - 7  granodiorite  K = Conductivity  of the g r a n o d i o r i t e i n the h o r i z o n t a l d i r e c t i o n  Kg = C o n d u c t i v i t y  of the g r a n o d i o r i t e i n the v e r t i c a l  g x  Z  K  v  = C o n d u c t i v i t y of the  volcanics  Kj = C o n d u c t i v i t y  of the  K. = C o n d u c t i v i t y  of the impermeable boundary  fault  13.8  8  K =l.42x10 4 Min(aniso)  22.3  direction  K =2.24x10  -8  gx  13.9  125  groundwater recharge the t o t a l  i n Chapter  precipitation  values a r e thus  6 i n d i c a t e d t h a t 13 t o 1 6 % o f  became g r o u n d w a t e r f l o w .  i n t h e same r a n g e b u t s l i g h t l y  The m o d e l  higher.  N o t e i n F i g u r e s 7.7 t o 7.11 t h e p o s i t i o n o f t h e d i s charge and recharge  areas.  The maximum w a t e r t a b l e e l e v a t i o n  examples i n d i c a t e t h a t t h e d i s c h a r g e area way up t h e m o u n t a i n s i d e a l t h o u g h observed  i n the f i e l d .  charge area vered  i s situated a long  no s i g n o f t h e t h i s  As m e n t i o n e d i n C h a p t e r  i s probably  restricted  by u n c o n s o l i d a t e d v a l l e y Intermediate  t o the v a l l e y  fill  was  6 the d i s bottom c o -  d e p o s i t s as i n t h e m i n i -  mum  examples.  and  minimum e x t r e m e s show t h a t w a t e r t a b l e e l e v a t i o n s a s l o w  as t h e minimum p o s i t i o n  s i m u l a t i o n s between t h e maximum  or as h i g h as about halfway  t h e minimum and maximum p o s i t i o n s h a v e t h e same discharge area. centages  between  acceptable  T h i s means t h a t t h e r a n g e o f f e a s i b l e  of the t o t a l  per-  p r e c i p i t a t i o n e n t e r i n g the groundwater  s y s t e m d r o p s f r o m 14 t o 2 2 % down t o 14-18% w h i c h v e r y w e l l w i t h t h e 13-16% range e s t i m a t e d l a n c e and t h e e s t i m a t e s of groundwater  corresponds  from t h e water ba-  recharge.  I n t e r p r e t a t ion In  the following d i s c u s s i o n the u n r e a l i s t i c  4A w i l l  any  g e o l o g i c u n i t the h i g h e s t value of c o n d u c t i v i t y i n the i s o n l y one f i f t h  the lowest  value.  Table  t o one o r d e r  7.3 i l l u s t r a t e s  I B , 3A  and  table  n o t be i n c l u d e d .  cases  that i n  of magnitude l a r g e r  than  When one c o n s i d e r s t h a t c o n d u c t i v i t i e s c a n  126  v a r y o v e r 10 the  o r d e r s o f m a g n i t u d e or more, i t i s c l e a r  modelling  vities  has  f o r the  conductivity  produced a very d e f i n i t i v e  different  of  the  7  of  the  volcanics  2.71x10"  7  m/s  2.82xl0"  7  t o 1.04x10"'  and  I t must be f o r the  there  m/s  while  are  butions  and  K  i n the  an  formation.  hydraulic  however, t h a t ratios  as  depicted  s i m p l e as  that ly  the  true  conductivity  from the  to b e l i e v e  simplest that  the  Nevertheless,  sen,  the  modelling  a vertical  condu-  to from  these answers  the  are  Theoretically  the  are  granodiorite  environchosen  w i t h i n an  the  order  geology  simulations  is  of not  show  v a r i e s only  slight-  most c o m p l e x g e o l o g y l e a d i n g  one  realistic.  geological configurations  indicates that conductivity  hydraulic  for  geologic  Even t h o u g h t h e  of  t o the  range  author f e e l s that  models, the  the  distri-  t o t a l discharge values  i n the  from the  horizontal hydraulic and  values.  values are  In c o n c l u s i o n ,  7  i t ranges  infinite conductivity  c o n d u c t i v i t i e s i n T a b l e 7.3 the  direction i t  hydraulic  i n T a b l e 7.2.  r e a s o n a b l e and  m a g n i t u d e of  The  ranges from 1.42x10"  v  m e n t s , r e c h a r g e r a t e v a l u e s and or c a l c u l a t e d are  m/s.  from  number o f p o s s i b l e c o n d u c t i v i t y  therefore,  each g e o l o g i c  varies  x  m/s.  stressed,  infinite  7  K  conducti-  hydraulic  vertical  permeable f a u l t  conductivity  an  horizontal  i n the  f r o m 7.41x10"' t o 7 . 3 2 x 1 0 "  ctivity  only  The  basement g r a n o d i o r i t e  1.42x10"" t o 1 . 5 2 x 1 0 " varies  units.  s e t of  that  the  granodiorite  has  choa  of a p p r o x i m a t e l y 5 x 1 0 "  conductivity  of  1x10"  7  m/s.  8  The  m/s  127  hydraulic m/s,  conductivity  similar  i s close  to l x l O ~  7  t o t h e v e r t i c a l component i n t h e g r a n o d i o r i t e  and t h e most p e r m e a b l e ductivity  of the v o l c a n i c s  zone, the f a u l t , has a h y d r a u l i c  of r o u g h l y 7 x l 0 ~  7  m/s.  con-  128  Chapter CONCLUSIONS AND  8.  RECOMMENDATIONS  I n t h i s t h e s i s an a t t e m p t h a s been made t o d e s c r i b e h y d r o g e o l o g y o f t h e Meager M o u n t a i n g e o t h e r m a l a r e a . main p u r p o s e o f t h e t h e s i s was  area.  A summary o f t h e m a j o r  presented  The  to develop a preliminary,  t h e m a t i c a l model o f t h e r e g i o n a l g r o u n d w a t e r  flow  f i n d i n g s of t h i s  the  ma-  i n the  research i s  below.  Summary and  Conclusion  Geography 1.  The  topography  rugged.  The  i n t h e Meager M o u n t a i n a r e a i s v e r y  relief  r a n g e s f r o m 425  z o n t a l d i s t a n c e s o f r o u g h l y 5 km. tems t e r m i n a t e a t t h e h e a d w a t e r s dient, youthful  streams.  The  t o 2700 m o v e r  hori-  Extensive glacier o f a number o f  sys-  high-gra-  streams produce a  radial  p a t t e r n of d r a i n a g e around the m o u n t a i n . 2.  Precipitation total  i n the c o a s t mountains  annual p r e c i p i t a t i o n  i s v a r i a b l e but a  r a t e o f 2.5  m/y  i s expected at  Meager M o u n t a i n . 3.  The mean a n n u a l r u n o f f o f t h e L i l l o o e t  River  mm/yr w h i l e r u n o f f m e a s u r e m e n t s a t M i l l e r  i s 1880  Creek which i s  a t a h i g h e r e l e v a t i o n a r e e s t i m a t e d t o be 2400 ±  300  mm/yr. 4.  The p o t e n t i a l area  evapotranspiration  i s a p p r o x i m a t e l y 500  mm/y.  i n t h e Meager  Mountain  129  5.  The  Meager C r e e k h o t s p r i n g s  have a c o m b i n e d d i s c h a r g e They r e p r e s e n t water 6.  and  Pebble Creek  hotsprings  r a t e of a p p r o x i m a t e l y  a minute f r a c t i o n  of t h e  45  1/s.  r e g i o n a l ground-  discharge.  A number of c o l d s p r i n g s Mountain area.  exist  throughout the  Most have d i s c h a r g e s  They r e p r e s e n t  a b o u t 1 t o 2%  of  the  Meager  l e s s than 5  1/s.  r e g i o n a l groundwater  flow.  Geology 1.  Meager M o u n t a i n south  of t h e G a r i b a l d i b e l t of  trending Quaternary volcanoes.  initially for  i s part  erupted  i n the  approximate the past  Pliocene  is  best  exposed i n the  south.  composed of d a c i t e f l o w s and older andesite 2.  The  of t h e  and  has  been dormant  The  older  portion  widespread andesite  The  younger n o r t h  and  half i s  l a v a domes o v e r l y i n g  the  t h r o u g h a basement c o n s i s t i n g of  older g r a n i t i c  volcanic eruptions  basement r o c k  and  flows.  v o l c a n i c s erupted  Tertiary  Meager M o u n t a i n  2500 y e a r s .  of t h e m o u n t a i n c o m p r i s e s m a i n l y  north-  thereby  rocks.  The  s e v e r e l y may  explosive  nature  have f r a c t u r e d  the  increasing i t s fracture permeabili-  ty. 3.  The  Lillooet  R i v e r and  with unconsolidated 250  m  in thickness.  gravels with  Meager C r e e k v a l l e y s a r e  deposits The  interbedded  varying  from zero  filled to  deposits  c o n s i s t of  till  lacustrine clay layers.  and  sand  over and  130  Hydrogeology 1.  The p r e l i m i n a r y Lillooet  basin  water balance undertaken i n d i c a t e s that  enteres the groundwater 2.  The Meager M o u n t a i n  f r a c t u r e survey joint  not supply s u f f i c i e n t  r o c k mass h y d r a u l i c opinion  that  there  indicates  two  s e t s , however, the study  data f o r t h e c a l c u l a t i o n of the  conductivity.  I t i s the author's  i s no s u i t a b l e method t o make  measurements of f r a c t u r e d representative  17% o f t h e p r e c i p i t a t i o n  system.  dominant, near v e r t i c a l did  f o r the e n t i r e  rocks i n the f i e l d  e s t i m a t e of h y d r a u l i c  surface  to attain a  conductivity  f o r the  f r a c t u r e p e r m e a b i l i t i e s of  various  r o c k mass a t d e p t h . 3.  The s t u d y o f p u b l i s h e d rock types revealed  that  the h y d r a u l i c  most f r a c t u r e d  lies  i n the 10"  It  is felt  rock  that  the hydraulic  ment g r a n o d i o r i t e s of  this  4.  7  i n the study area  t o 10"  I t c a n be shown t h a t water t a b l e tain  system.  vations, the  8  m/s  could  from a v e r y  the discharge area  1 1  m/s  range.  of the base-  i s at the high  fractured  end  nature.  be e x p e c t e d .  t h e most l i k l y  i s a t an i n t e r m e d i a t e Apart  to 10"  conductivity  r a n g e , due t o t h e i r h i g h l y  V a l u e s of 10"  7  c o n d u c t i v i t y of  p o s i t i o n f o r the  elevation  i n t h e moun-  few s p i n g s a t h i g h e r  i s believed  ele-  t o be c o n f i n e d  s e c t i o n o f t h e v a l l e y o v e r l a i n by u n c o n s o l i d a t e d  de-  posits. 5.  The f r a c t u r e h y d r a u l i c all  the volcanic  conductivity  l a y e r s has g r e a t e r  that  occurs  across  c o n t r o l over the  to  131  groundwater flow than t h e i n t e r g r a n u l a r h y d r a u l i c conductivity  d i f f e r e n c e s between l a y e r s .  entire volcanic pile unit. fill  i s c o n s i d e r e d a s one h y d r o g e o l o g i c  The basement r o c k a n d t h e u n c o n s o l i d a t e d a r e two o t h e r d i s t i n c t h y d r o g e o l o g i c  study The  10"  5  t o 10"  2  m/s  basement r o c k the v e r t i c a l  observations are estimate t o  f o r the unconsolidated deposits, 10"  f o r t h e basement r o c k a n d 10"'-  for the v o l c a n i c s .  times  i s p e r h a p s a s much a s 5 t i m e s direction  than  t o 10"" m/s  greater i n  i n the h o r i z o n t a l fracturing.  of t h e v o l c a n i c rock  direction  The h y d r a u l i c  i s p e r h a p s a s much a s 5  greater i n the h o r i z o n t a l d i r e c t i o n  vertical  5  7  The h y d r a u l i c c o n d u c t i v i t y o f t h e  t o the extensive v e r t i c a l  conductivity  lic  u n i t s i nthe  r e p r e s e n t a t i v e h y d r a u l i c c o n d u c t i v i t i e s as determined  t o 10"* m/s  due  valley  area.  by p u b l i s h e d d a t a a n d f i e l d be  In t h i s study, the  d i r e c t i o n due t o l a y e r i n g .  c o n d u c t i v i t y i n t h e basement r o c k  than i n the  The v e r t i c a l i s similar  hydrauto that  in the v o l c a n i c rock. The  groundwater d i s c h a r g e  i n t h e Meager C r e e k b a s i n  c u l a t e s t o be 1 4 . 5 % o f t h e t o t a l p r e c i p i t a t i o n , an a n n u a l r a i n f a l l  r a t e o f 2.5 m/y.  entire Lillooet  assuming  This discharge  range c o r r e l a t e s w e l l w i t h t h e 17% c a l c u l a t e d  cal-  value  f o r the  b a s i n through t h e use of a water  balance.  132  Mathematical 1.  Modelling  The  p a r a m e t e r s t h a t must be  the  groundwater flow  flow,  2)  the  e q u a t i o n of  boundary c o n d i t i o n s 4)  the  The  i n the  flow  around the  the  include,  within  the  b o u n d a r i e s of  of h y d r a u l i c  analysis using  flow  variations. hydraulic  vations  are  v a r i e d but  trarily  and  remains  Consequently,  the  d e p t h of  that  flow one.  field  of  the  The  t h a t d i s c h a r g e out  4.  d e p t h of  flow.  s i b l e and  the  The  the with to  main s i -  water t a b l e i s chosen  thermal waters at  there  f o r the  ele-  arbi-  of  flow the  Meager  Brown (1977)  i s no  This  s y s t e m , however  cannot  geochemical studies  is a  prove  i t illustrates  s y s t e m i s i n d e p e n d e n t of flow  the  indicates  thermal waters probably  Therefore, a shallow  and  evidence that  mathematical modelling  i t i s a shallow  likely  reveales  with  i n the  flow  w a t e r t e m p e r a t u r e e v e r e x c e e d e d 140°C.  shallow  region,  constant.  (1980) i n d i c a t e t h a t  the  the  is insensitive  M o u n t a i n c o m p l e t e d by Hammerstrom and  that  the  of  conductivity  c o n d u c t i v i t y and  geochemical studies  Clark  3)  c o n d u c t i v i t y , undergoes moderate changes  m u l a t i o n s the  The  region  t h e p r o g r a m FOPS  w a t e r t a b l e e l e v a t i o n v a r i a t i o n s and d e p t h of  the  region,  amount of d i s c h a r g e v a r i e s d i r e c t l y  hydraulic  3.  1)  model  region.  sensitivity  that  area  spatial distribution  values 2.  i n an  known t o m a t h e m a t i c a l l y  the  system i s f e a -  i n d i c a t e i t i s the  most  situation.  p r o g r a m FREESURF1 was  used f o r the  main  simulations  133  in  this  meter the  report.  The  most a c c u r a t e l y  i n t h e Meager M o u n t a i n a r e a  simulations,  the  discharge  known v a r i a b l e  i s the  value  discharge.  logical  configurations  t e r m i n e d t h a t 14-18% of the the  The  value  determined o f 14.5%  i n the  4 geo-  simulations  total precipitation  the  w a t e r b a l a n c e s t u d i e s , and  determined  i n t h e Meager C r e e k  de-  enters  g r o u n d w a t e r zone w h i c h c o r r e l a t e s w e l l w i t h  of 17%  and  hydraulic  c a l c u l a t e d f o r the  considered.  In  i s held constant  a p o s s i b l e r a n g e o f w a t e r t a b l e e l e v a t i o n s and c o n d u c t i v i t y d i s t r i b u t i o n s are  para-  value the  baseflow  studies. 5.  The  bottom hole  simulations 6.  The  fluid  pressure  v a r i e s w i t h i n 5 t o 10%  mathematical simulations  values  a t 900  f o r the  hydraulic  the  horizontal direction  for  the v e r t i c a l  for  the  one  order  most  the  likely  5x10"  actual  fault  8  m/s  1x10"  basement r o c k ,  f o r the  the pressure.  basement r o c k s ,  i n the 7  of  isostatic  i n d i c a t e d the  i n the  7x10"  of m a g n i t u d e of  i n any  c o n d u c t i v i t y t o be  direction  v o l c a n i c s and  of  m  in 7  1x10"  zone.  7  Within  values.  Recommendat i o n s An  accurate  estimate  of  the  c h a r g e i n t h e Meager C r e e k b a s i n overall hydraulic ment r o c k .  amount of g r o u n d w a t e r w i l l allow  c o n d u c t i v i t y t o be  A d e t a i l e d water balance  t h i s discharge  value.  The  a more  assessed  precise  f o r the  i s recommended t o  w a t e r b a l a n c e w o u l d have t o  p e r f o r m e d o v e r a number o f y e a r s and  dis-  baseattain be  would i n v o l v e the f o l -  134  l o w i n g m e a s u r e m e n t s : 1) M e a s u r e t h e volume c h a n g e o f t h e g l a ciers  i n the basin  area t o determine t h e i r c o n t r i b u t i o n t o  basin  discharge.  floor  to the higher elevations  2) M e a s u r e t h e p r e c i p t a t i o n to ascertain  from t h e v a l l e y  the annual p r e c i -  p i t a t i o n and t h e change of p r e c i p i t a t i o n v a l u e s w i t h tion.  3) M e a s u r e t h e d i s c h a r g e y e a r - r o u n d a t t h e s t a g e s i t e s  currently just the  i n use and i n s t a l l  a n o t h e r on t h e L i l l o o e t  d i s c h a r g e out of t h e a r e a and s u b - b a s i n  4) M e a s u r e t h e e v a p o r a t i o n by u s i n g  A fracture  survey  i n the v o l c a n i c s  general trends of f r a c t u r i n g . hydraulic  conductivity  whether t h e f r a c t u r e s hydrogeologic reveal  reveal  c a l c u l a t i o n s but would  A more r e f i n e d g e o l o g i c a l  with  i n the  and p o s s i b l y  fracture density conductivity  configuration  and  to possib-  at depth. hydraulic  d i s t r i b u t i o n f o r t h e basement r o c k w i l l  continued d r i l l i n g  and t e s t i n g .  evolve  As t h e s e two v a r i a b l e  p a r a m e t e r s become more r e f i n e d , m a t h e m a t i c a l s i m u l a t i o n s the  hydrogeologic environment w i l l  results.  to t h i s p r o j e c t production  a l s o y i e l d more  Mathematical modelling w i l l throughout  stages.  useful  determine  as s t a t e d  i n t e r p r e t a t i o n of t h i s r e p o r t  zones of h i g h e r h y d r a u l i c  conductivity  i n the area.  The s u r v e y m i g h t n o t be  higher  radia-  would g i v e t h e  are mainly v e r t i c a l  zones of r e l a t i v e l y  discharges.  pan d a t a and s o l a r  t i o n data t o estimate the evapotranspiration  ly  River  s o u t h o f i t s c o n f l u e n c e w i t h Meager C r e e k t o c a l c u l a t e total  for  eleva-  of  refined  d e f i n i t e l y be o f v a l u e  i t s exploration,  development and  135  The  two  limiting  Mountain geothermal  factors  f o r d e v e l o p m e n t of t h e Meager  p r o j e c t are  t h e basement r o c k and  t h e h y d r a u l i c c o n d u c t i v i t y of  the temperature  of t h e r o c k a t  Temperature l o g g i n g of the d r i l l  h o l e s has  promising  Hydraulic conductivity tests  have n o t  geothermal  been u n d e r t a k e n .  conductivity all  gradients.  ctivity  I t i s i m p e r a t i v e t h a t down h o l e  t e s t s be p e r f o r m e d  from the top t o the bottom  and  may  with depth.  of  be  Near s u r f a c e , the h y d r a u l i c condu-  sufficiently  be  sufficiently  h i g h f o r p r o d u c t i o n but  may  be  too  The  author  too low.  h i g h f o r p r o d u c t i o n but  p e r a t u r e may  for  very  h o l e s t o r e v e a l the h y d r a u l i c c o n d u c t i v i t y d i s t r i b u t i o n  spatially  vity  revealed  depth.  At d e p t h ,  the p r o m i s i n g  exist  t e s t s on is very  be  the h y d r a u l i c c o n d u c t i -  and  project. drilling  In the  initial  are necessary  r e g i o n f o r development.  Now  that  to this  been d e l i n e a t e d i n t h e S o u t h R e s e r v o i r a r e a a more  sophisticated panies  may  f e e l s t h a t a c h a n g e of s t r a t e g y i s i n o r d e r  stages, e x p l o r a t i o n geophysics  r e g i o n has  tem-  low.  t h e Meager M o u n t a i n g e o t h e r m a l  outline  the temperature  the  technology that perform  f r a c t u r e d rock. expensive,  is essential  n e e d s t o be e m p l o y e d .  Numerous com-  s p e c i a l i z e d down h o l e The  however t h e  employment of t h e s e  hydrogeologic companies  i n f o r m a t i o n they can  to the p r o j e c t at t h i s  time.  generate  136  APPENDIX I  GLACIAL BASAL MELT FLUX CALCULATIONS IN THE MEAGER CREEK BASIN  137  The g o v e r n i n g  equation  f o r the rate of g l a c i a l  basal  m e l t due t o t h e e a r t h ' s g e o t h e r m a l f l u x i s dz _ o dt pL q  dz where ^ q  time, ice  (W/m ), P t h e d e n s i t y o f  t h e geothermal heat f l u x  Q  2  (Kg/m ) a n d L t h e l a t e n t h e a t o f m e l t i n g 3  world and  i s t h e r a t e of change of t h i c k n e s s of i c e w i t h  average heat f l u x  latent  3.35xl0"  5  i s 0.05 W/m  heat of m e l t have v a l u e s  o f 900 Kg/m  3  and  J/Kg r e s p e c t i v e l y .  W/m  (Lewis  This  i s ten times  and S o u t h e r ,  v a r i e s f r o m 0.1 t o 0.93  1 9 7 8 ) w i t h an a v e r a g e o f 0.5  the world average.  t h i c k n e s s of t h e g l a c i e r s w i t h time area  The  and t h e d e n s i t y of i c e  2  I n t h e Meager M o u n t a i n a r e a 3  (J/Kg).  W/m . 2  The r a t e o f c h a n g e o f i n t h e Meager  Mountain  i s therefore § ^ - 1.66 dt The a r e a  10  X  m/s  of the g l a c i e r s c o n t r i b u t i n g t o the flow i n  Meager C r e e k i s a p p r o x i m a t e l y  51.4 Km  or 5.14xl0  2  f i g u r e was c a l c u l a t e d u s i n g a p l a n i m e t e r The v o l u m e Q o f f l u i d Q  7  3  runoff  2  and topography  This map.  r e l e a s e c a n now be c a l c u l a t e d a s  = g dt  =  dz dt  =  0  >  Q  9  m  3  /  s  The m e a s u r e d g r o u n d w a t e r f l o w o u t o f t h e a r e a m /s;  m.  t h e r e f o r e t h e c o n t r i b u t i o n of b a s a l g l a c i a l i n t h e w i n t e r months  i s 2.5 melt t o  s h o u l d n o t e x c e e d 3 t o 4%.  APPENDIX II  CONTOURED-POLE PLOTS OF FRACTURE DATA  III J o i n t  s e t #1  [~jjoint  s e t #2  Hjoint  s e t #3  i^Joint  s e t #4  HEM I FOR: SITE OBSERVATIONS: 190 POPULATION: 190 GEODfiT  CONTOUR  -  LOUEP  PLOT  SPHERE SROI  EOUOL :  5  fiPEP, POLFlP  €02  850  H  PLOT  46]  OCn'  E  1100  t l .  CO  CEODAT - LOUER H E M I S P H E R E EQUAL CONTOUR P L O T F O R : S I T E SR03 : 3 OBSERVATIOHS: 200 POPULATION: 200  AREA POLAR 602 300 N  PLOT «66  606  E  ?ce  «1  C E O D A T - LOWEP H E M I S P H E R E E Q U A L A R E A CONTOUR P L O T F O R : S I T E SR04 ! 5 60) OBSERVATIOHS: 99 POPULATION: 99  POLAR 906 H  PLOT 463  700  E  BSC  •  CEODAT - LOWER HEMISPHERE EOUAL AREA POLAR PLOT CONTOUR PLOT FOR: SITE SR05 : 5 €01 375 N 464 300 E 940 « l . OBSERVATIONS: lee POPULATION: tee  CE0DAT - LOWER HEMISPHERE EQUAL APEA POLAR PLOT CONTOUR PLOT FOR: SITE SR06 : 5 602 000 N : 462 900 E : 1000 ti. OBSERVATIONS: 199 POPULATION: 199  CEOHAT - LOUER HEMISPHERE EQUAL AREA POLAR PLOT CONTOUR PLOT FOR: SITE SR07 : 5 602 066 N : *6l 500 E : 1666 f l . OBSERVATIOHS: 199 POPULATION: 199  CEOIiAT - LOWER HEMISPHERE EQUAL AREA POLAR PLOT CONTOUR PLOT FOR: SITE SR08 : 5 662 266 N : *67 950 E : 740 « I . OBSERVATIOHS: 258 POPULATION: 230  GEOHAT - LOWER HEM I SPHERE EOUAL UREA POLAP PLOT CONTOUR PLOT FOR: SITE S R 9 B « 9 A : 5 661 OOO N • 463 b?: £ OBSERVATIONS: 348 POPULATION: 348  GEOUAT - LOWER HEMISPHERE EOUAL AREA POLAR PLOT CONTOUR PLOT FOR: SITE SR18 : 5 604 660 N : 466 OBSERVATIONS: 216 POPULATION: 216  CEODAT - LOWER- HEMISPHERE EQUAL AREA POLAR PLOT CONTOUR PLOT FOR: SITE SR11 : S 6 0 i 325 N : 463 966 E ! 990 f l . OBSERVATIONS: 200 POPULATION: 200  CEODAT - LOUER HEMISPHERE EQUAL AREA POLAR PLOT CONTOUR PLOT FOR: SITE SRI2 : 5 60S 100 N : 467 700 E : 1220 f l OBSERVATIONS: 201 POPULATION: 201  M  CEODMT  -  LOWER  HEM I S P H E R E  CONTOUR PLOT FOR: OBSERVATIONS: 170 POPULATION: 170  SITE  EOUAL  SRI3  : 5  N  AREA 603  POLAR 100  H  PLOT :  46;  675  E  :  1600  rl.  CONTOUR CEOBAT  -  LOWER  PLOT OBSERVATIONS: POPULATION:  FOR:  HEMISPHERE  149 M »  SITE  EQUAL SR14  AREA  : 5  603  POLAR 500  PLOT N  :  461  250  E  :  1300  «1.  CEODAT - LOUER HEMISPHERE EQUAL AREA ROLAR PLOT CONTOUR PLOT FOR: SITE SRI5 : 3 £06 EI30 N | 461 650 E : 760 .1 OBSERVATIONS: 103 POPULATION: 103 H  CEODAT - LOUER HEMISPHERE EQUAL AREA POLAR PLOT CONTOUR PLOT FOR: SITE SRI6 : 3 600 650 N : 461 025 E : 760 «1. OBSERVATIOHS: 101 POPULATION: IOI N  I— 1  GEGDRT - LOWER HEMISPHERE EQUAL AREA POLRP PLOT CONTOUR PLOT FOR: SITE 858 N OBSERVATIONS: 160 POPULATION: 100 SRi?  : 5 600  : 46i  450  E :  7se  #V.  CEODAT - LOWER HEMS !PHERE EOURL AREA POLAR PLOT SITE SRI8 : 5 666 850 N : 462 656 E : 748 OBSERVATIONS: 116 POPULATION: l i e CONTOUR  PLOT  FOR:  N  «1.  ^.^.cV??"  MEMISPH  OSATI'ON'SV^ POPULATION: i e ?  «E EQUAL AREA POLAR PLOT "> »' " ' «< «' • •  S,TE S  6:6  N  CEODAT - LONER HEtllSPHERE EOUAL AREA POLAR PLOT CONTOUR PLOT FOR: SITE SR26 : 5 660 750 N : 464 756 E I OBSERVATIONS: 102 ' POPULATION: 1 0 2  666 . 1 6  6  6  CEODAT - LOWER HEMISPHERE EQUAL AREA POLAR PLOT CONTOUR PLOT F OR: SITE SR21 : 5 sen 900 N : 4£ OBSERVATIONS: 131 POPULATION: 151  CEODAT - LOWEF HEMISPHERE EOUAL AREA POLAR PLOT COttfC'lH P LOT FOR: SITE SR22 I 5 £01 225 N j OBSERVATIONS: 200 POPULATION: 2B8  Ac  N  CEODAT - LOWER HEMISPHERE EQUAL AREA POLAR PLOT CONTOUR PLOT FOR: SITE SR24 : S 602 450 N : 465 375 E : 1050 l l . OBSERVATIONS: 100 POPULATION: IOO N  or  o  CEODAT - LOUER HEMISPHERE EOUAL AREA POLAR PLOT COIITOUR PLOT FOR: SITE SRt5 : 5 £94 £75 t< ; £ f OBSERVATIONS: 148 POPULATION: MB 4  H  E  :  ,  3  &  e  APPENDIX  III  RIVER STAGE MEASUREMENTS AT MEAGER CREEK HOTSPRINGS BRIDGE, 19  153  Water L e v e l O b s e r v a t i o n s a t Meager Creek, 1979  Water L e v e l (in Feet) Date 1979  Time  Observed  Crest  18  1545  152. 58  19  0930  152. 58  153. 23  25  0910  152. 43  153. 23  1235  152. 58  3  1525  152. 08  154. 0  4  1510  152. 25  152. 5  5  1650  152. 65  152. 88  6  1700  152. 78  153. 18  7  1515  152. 63  153. 28  8  1510  153. 8  154. 28  9  1910  153. 34  154. 18  10  1930  153. 81  154. 13  11  1820  153. 23  154. 08  12  1930  153.,13  153. 43  13  1900  152.,7  153. 0  14  2120  153.,08  153. 38  15  2100  153.,18  153. 68  16  1130  152.,73  17  2025  153.,68  18  2045  153..88  154. 08  19  2030  153..88  154.,18  20  0900  152,.88  154.,18  21  1825  153..68  154.,38  22  1830  153,.43  153.,68  23  1915  153,.48  153.,58  24  2030  153,.28  153..58  25  1600  153 .28  153..38  26  1900  153 .38  153,.58  27  1605  153 .33  153,.48  28  1100  152 .83  153,.53  29  1630  153 .03  153,.48  30  1535  153 .13  153 .38  31  1915  153 .33  153 .48  June  July  154  Water L e v e l (in Feet) Date  1979  Time  Observed  Crest  August 1  1635  153.28  153.48  2  1530  153.13  153.43  3  1645  153.08  153.33  4  1645  152.98  153.28  5  1615  152.83  153.18  6  1420  152.48  152.98  7  1900  152.86  8  1630  153.18  9  1930  153.39  -  -  10  1530  153.14  153.68  11  1920  153.45  153.73  12  1810  153.59  153.83  13  1915  153.68  154.18  14  1825  154.25  154.13  15  2030  153.25  153.78  16  1940  153.31  153.73  17  1700  153.25  153.58  18  1900  153.19  153.83  19  1845  153.23  153.58  20  2100  153.55  153.98  21  1845  153.78  22  1920  153.73  154.43  23  2035  153.57  154.18  24  1900  153.31  153.88  25  1915  153.48  153.88  26  1910  153.58  153.93  27  1130  152.95  2015  153.34  1050  152.85  1945  153.51  1200  152.71  28 29  154.13  154.03  1945  153.61  154.03  30  1945  153.28  153.98  31  1845  152.98  153.53  Water L e v e l (in Feet) Date 1979  Time  Observed  Crest  September 1  1945  153.18  153.58  2  1200  153.21  154.58  1945  153.84  154.18  3  1245  153.68  155.98  4  2000  153.08  153.83  5  1000  153.43  153.93  1915  153.25  6  1945  152.48  7  -  1945  152.88  8  1945  154.05  9  1845  152.88  10 11  -  154.48  -  -  1300  152.18  -  -  1655  152.48  -  12  -  -  13  1910  153.03  14  1845  153.28  153.58  15  1100  152.73  153.53  2155  153.18  153.68  1240  152.68  2030  152.98  -  16 17  -  -  0930  152.48  2030  153.2  153.38  18  1955  153.26  153.48  19  0945  152.68  153.53  1700  150.71  November 3 December 10  1505  150.72  APPENDIX I V  DISCHARGE  CALCULATION AT THE  MEAGER CREEK STAGE S I T E , DEC. 10, 1  157  The on  cross s e c t i o n a l area  December 10,  late  the  1979  was  stream v e l o c i t y  A o f t h e Meager C r e e k  c a l c u l a t e d t o be  the Manning equation JU49  s e c t i o n a l area  dient  s l o p e and  R  Z / 3  n  S  estimate  to  =1.23  to the wetted p e r i m e t e r ) ,  i s used  mVs.  which  (ratio  S i s the  n i s the Manning f r a c t i o n c o e f f i c i e n t .  o f n i s 0.04 t o 1.53  t o 0.05.  m/sec.  f r o m Q=uA, i s t h e r e f o r e 3.28 3.7  calcu-  2  t h e M e a g e r C r e e k s t a t i o n , R=0.76, S = 2 . 6 3 x l 0 "  leads  To  2  i s the v e l o c i t y , R i s the h y d r a u l i c r a d i u s  cross  sonable  m.  ? / 7 L.  states that  where u  2.7  station  The  t o 4.10  The  J  3  or  a  Manning  discharge, m /s  and  Q,  of  graFor  reaequation  obtained  approximately  158  APPENDIX V  DECEMBER DAILY DISCHARGES OF THE LILLOOET RIVER NEAR PEMBERTON ( 1 9 7 7 - 1 9 7 9 )  December  D a i l y Discharge of the L i l l o o e t  Near Pemberton i n m/s  Day  1977  River,  (1977-1979)  1978  1979  1  32.0  22.7  24.1  2  31.4  22.4  23.8  3  32.6  22.1  23.5  4  30. 3  21.8  23.2  5  29.2  21.5  22.9  6  28.3  21.2  22.9  7  28.0  21.0  23.1  8  27.5  20.7  23.2  9  26.9  20.4  24.9  10  27.5  20.1  25.5  11  28.3  19.8  23.8  12  34.0  19.7  22.9  13  33.1  19.5  19.8  14  31.1  19.4  21.5  15  28.3  19.3  20.7  16  26.9  19.1  20.1  17  25.5  19.0  21.0  18  27.8  18.8  24.6  18.7  36.0  19  27.2  20  26.9  18.5  32.6  21  26.6  18.4  29.7  22  26.3  18.3  28.0  23  26.1  18.1  26.6  24  25.8  18.0  25.5  25  25.5  17.8  24.6  26  24.9  17.7  24.4  27  24.6  17.6  23.5  28  24.4  17.4  22.9  29  24.1  17.3  22.4  30  23.8  17.1  22.1  31  23.8  17.0  21.9  858.7  600.4  751.7  Total MEAN  27.7  19.4  24.2  MAX  34.0  22.7  36.0  MIN  23.8  17.0  19.8  160  References  A n d e r s o n , R.G., The g e o l o g y o f t h e v o l c a n i c s i n t h e Meager C r e e k map a r e a , s o u t h w e s t e r n B r i t i s h C o l u m b i a , B.Sc. t h e s i s , D e p t . 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