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Some aspects of the oceanographic structure in the Jervis Inlet system Lazier, John Robert Nicholas 1963

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SOME ASPECTS OP THE OCEANOGRAPHIC STRUCTURE IN THE JERVIS INLET SYSTEM  by John Robert Nicholas L a z i e r  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the department of PHYSICS We accept t h i s thesis as conforming to the required standard  THE  U N I V E R S I T Y  OF  B R I T I S H  June, 1963  C O L U M B I A  • I n presenting t h i s , t h e s i s i n p a r t i a l f u l f i l m e n t  of  the requirements for an advanced degree at the U n i v e r s i t y of . B r i t i s h Columbia, I agree a v a i l a b l e for reference  that the L i b r a r y s h a l l make i t  and study.  I f u r t h e r agree  that  freely per-  mission for extensive copying of t h i s t h e s i s f o r . s c h o l a r l y purposes may be granted by* the Head of my Department or by", his representatives. c a t i o n of t h i s  It  is.understood  t h e s i s for f i n a n c i a l gain s h a l l not be allowed  without my w r i t t e n ' p e r m i s s i o n .  Department of  \  The U n i v e r s i t y of B r i t i s h Columbia, Vancouver 8, Canada. Date  that copying, or p u b l i -  ii ABSTRACT  The variations i n the distributions of temperature,  salinity,  and dissolved oxygen content i n the water i n the Jervis system of inlets,  between July 1961 and March 1963* have been examined i n order  to ascertain net current patterns and interactions between the The depths of the entrance s i l l s  inlets.  divide the i n l e t s into two groups.  Of the four i n l e t s i n the system three possess shallow s i l l s which force the tide water to enter the i n l e t s i n a turbulent j e t .  The  c i r c u l a t i o n pattern resulting from the influence of this jet on the i n l e t is proposed.  In contrast, the s i l l of the largest i n l e t i n the  system (Jervis) is deep and the t i d a l flow does not destroy the v e r t i c a l s t r a t i f i c a t i o n i n the i n l e t to any appreciable degree.  The  r e l a t i v e l y small fresh water runoff into Jervis creates a weak estuarine c i r c u l a t i o n r e s u l t i n g i n slow renewal of the intermediate and deep water.  The low oxygen concentrations found at mid-depths  near the head of Jervis are attributed to this abnormally slow renewal. A mid-depth o s c i l l a t o r y flow of unknown period was found during the winter of 1962-63 i n Jervis I n l e t .  This flow is attributed to strong  south-westerly winds which raise the water level i n Jervis forcing a mid-depth outflow.  Inlet  The direction of this flow possesses a  negative correlation with the depth of the surface layer.  viii  ACKNOWLEDGMENTS  The author wishes to express h i s s i n c e r e gratitude to those who contributed to the completion of this sttadyt  In particular he  wishes to thank Dr. G. L. Pickard und#r whose direction, encouragement, and helpful adyice thi» work was carried out.  The  assistance and co-operation of Gapt&ih V. Dale-Johnson of the research ship C.S.S. E h k o l i , and his crew are gratefully M  acknowledged.  M  The author i s also indebted to H. Heckl, H. Wilke,  and M. Storm for technical assistance, and to Mrs. E. Storm for preparing the typescript.  F i n a l l y , sincere appreciation i s expressed  to the Department of Mines and Technical Surveys for leave and financial assistance during the time of this study.  iii  TABLE OP CONTENTS  page I II  INTRODUCTION . . . . . .  . . . . .  SHALLOW SILLED INLETS . . . . . . . Proposed Current Pattern . . . ., Princess Louisa Inlet . . . . . The Deep Layer . . . ,  III  V  . . . . . . . . . . .  . . . . . .  . . . . .  1 5 5 11 20  . . . . .  Seohelt Inlet System  25  Narrows Inlet . . . . . . . . . . .  33  DEEP SILLED INLETS . . . . . . . . . . . .  37  Jervis Inlet . . . . . . . . . . . .  37  The Surface Layer and Mid-depth Plows  46  Oxygen Minima . . . . .'. . . IV  . . .  *. . . . .  . '. • . . . .  48  . . . . . . . . . . . . . .  50  APPENDIX . . . . . . . . . . . . . . . . . . . . . . .  52  References . . . . . . . . . . . . . . .  54  SUMMARY . . . . .  . . . .  . . . . . . .  iv LIST OF FIGURES Figure  2.  Average annual v a r i a t i o n of the f l o o d t i d e water density  page  5  Hypothetical schema of a shallow s i l l e d i n l e t f o l l o w i n g a f l o o d t i d e i n spring  page  6  Changes i n the v e r t i c a l s a l i n i t y gradient when subjected to the indicated shear  page  7  Hypothetical schema of a shallow s i l l i n l e t f o l l o w i n g a f l o o d t i d e i n autumn  page  9  Changes i n the s a l i n i t y p r o f i l e i n a shallow s i l l i n l e t as the density of the flood t i d e increases i n the autumn  page  9  7«  Princess Louisa I n l e t . . . . .  page 11  8.  Longitudinal p r o f i l e of temperature, s a l i n i t y and dissolved oxygen i n Princess Louisa I n l e t , f o r March, 1962  page 12  Average v e r t i c a l temperature, s a l i n i t y and oxygen p r o f i l e s f o r March and May 1962  page 13  Average v e r t i c a l temperature, s a l i n i t y and oxygen p r o f i l e s f o r Princess Louisa I n l e t during May and July 1962  page 15  Average v e r t i c a l temperature, s a l i n i t y and oxygen p r o f i l e s f o r J u l y and October 1962  page 16  Average v e r t i c a l p r o f i l e s f o r Princess Louisa I n l e t during October and November 1962  page 18  3. 4. 5. 6.  9. 10.  11. 12. 13.  Average v e r t i c a l p r o f i l e s f o r Princess Louisa I n l e t during November 1962 and January 1963 • • page 18  14.  Average v e r t i c a l p r o f i l e s f o r Princess Louisa I n l e t during January and February 1963  page 19  Average v e r t i c a l p r o f i l e s f o r Princess Louisa I n l e t during February and March 1963  page 20  Temperature, s a l i n i t y , and oxygen concentration i n the deep layer of Princess Louisa I n l e t p l o t t e d against time  page 21  Comparison between the v a r i a t i o n of flood t i d e density and deep water density with time  page 23  15. 16.  17.  V  LIST OF FIGURES (Continued) Figure 18.  Sechelt I n l e t System  f a c i n g page 25  19.  Temperature, s a l i n i t y , and d i s s o l v e d oxygen d i s t r i b u t i o n s i n Sechelt I n l e t during J u l y I96I  f a c i n g page 27  Temperature, s a l i n i t y , and d i s s o l v e d oxygen d i s t r i b u t i o n s i n Sechelt Inlet during November 1961  f a c i n g page 27  Temperature, s a l i n i t y and d i s s o l v e d oxygen d i s t r i b u t i o n s i n Sechelt I n l e t during March 1962  f a c i n g page 28  20.  21.  22.  Temperature, s a l i n i t y and dissolved oxygen d i s t r i b u t i o n s i n Sechelt I n l e t during May 1962. f a c i n g page 28  23.  Temperature, s a l i n i t y and dissolved oxygen d i s t r i b u t i o n s i n Sechelt I n l e t during J u l y 1962  f a c i n g page 29  Temperature, s a l i n i t y and dissolved oxygen d i s t r i b u t i o n s i n Sechelt I n l e t during October 1962  f a c i n g page 29  Temperature, s a l i n i t y and d i s s o l v e d oxygen d i s t r i b u t i o n s i n Sechelt I n l e t during November 1962 .  f a c i n g page 30  Temperature, s a l i n i t y and d i s s o l v e d oxygen d i s t r i b u t i o n s i n Sechelt I n l e t during January 19&3  f a c i n g page 30  24.  25.  26.  27.  28.  29.  30.  31.  V e r t i c a l temperature p r o f i l e s near the head, middle and mouth of the Sechelt-Salmon I n l e t System during November 18th 1962  page 30  Temperature and oxygen p r o f i l e s near the head and mouth of the Sechelt-Salmon I n l e t System during January 20th, I963  page 31  Temperature, s a l i n i t y and dissolved oxygen d i s t r i b u t i o n s i n Sechelt I n l e t during February 1963  f a c i n g page 31  Temperature, s a l i n i t y and dissolved oxygen d i s t r i b u t i o n s i n Sechelt I n l e t during March 1963  f a c i n g page 30  Temperature, s a l i n i t y and d i s s o l v e d oxygen d i s t r i b u t i o n s i n Sechelt I n l e t during July 1957  f a c i n g page 32  vi  LIST OF FIGURES (Continued) Figure 32.  Vertical profiles of temperature, s a l i n i t y and dissolved oxygen i n Narrows Inlet  32.  (continued) Vertical profiles of temperature, s a l i n i t y and dissolved oxygen i n Narrows Inlet . facing page 35  33'  Average v e r t i c a l profiles of temperature and s a l i n i t y for Jervis Inlet during March 1962 . . . . .  3 3 a . Longitudinal section of dissolved oxygen i n Jervis Inlet during March 1962 . . . . . . . . 34«  Vertical profiles of temperature, s a l i n i t y and dissolved oxygen at three positions i n Jervis Inlet during March and May 1 9 6 2 * . . . . . .  34*. Longitudinal section of dissolved oxygen i n Jervis Inlet during May 1962 35*  Vertical profiles of temperature, s a l i n i t y and dissolved oxygen at three positions i n Jervis Inlet during May and July 1962  3 5 a . Longitudinal section, of dissolved oxygen i n Jervis Inlet during July 1962 . 36.  Vertical profiles of temperature, s a l i n i t y and dissolved oxygen at three positions i n Jervis Inlet during July and October 1962 . . . . . .  3 6 a . Longitudinal section of dissolved oxygen i n Jervis Inlet duringOctober 1962 37.  Vertical profiles of temperature, s a l i n i t y and dissolved oxygen at three positions i n Jervi3 Inlet during October and November 1962 . . . .  5 7 a . Longitudinal section of dissolved oxygen i n Jervis Inlet during November 19&2 . . . . . . 38.  page 3&  facing page 38 facing page  39  facing page 38 facing page 40 facing page 41 facing page 42 facing page 41 facing page 43 facing page 44  Vertical profiles of temperature, s a l i n i t y and dissolved oxygen at three positions i n Jervis Inlet during November 1962 and January 1963 • . f a c i n g page 44  3 8 a . Longitudinal section of dissolved oxygen i n Jervis Inlet during January I 9 6 3 39.  facing page 34  V e r t i c a l profiles of temperature, s a l i n i t y and dissolved oxygen at three positions i n Jervis Inlet during January and February 1963 * • • •  facing page  44  faoing page 45  vii LIST OF FIGURES (Continued) Figure 39a. Longitudinal section of dissolved oxygen i n J e r v i s I n l e t during February 1963 40.  V e r t i c a l p r o f i l e s of temperature, s a l i n i t y and dissolved oxygen at three positions i n J e r v i s I n l e t during February and March 1963  40a. Longitudinal section of dissolved oxygen i n J e r v i s I n l e t during March I963 41.  S a l i n i t y at 50 and 100 metres at s t a t i o n Je. 3» and the thickness of the surface layer p l o t t e d against time  f a c i n g page 46  f a c i n g page 45 f a c i n g page 46  page 46  Figure  THE  JERVIS  i  INLET  SYSTEM  I.  1  INTRODUCTION  The " J e r v i s I n l e t system" (figure 1) i s comprised of J e r v i s , Princess Louisa, Sechelt, Salmon and Narrows I n l e t s .  The seaward  end or mouth of J e r v i s I n l e t i s located about 4 5 miles northwest of Vancouver, B r i t i s h Columbia.  The p h y s i c a l c h a r a c t e r i s t i c s of these  i n l e t s are s i m i l a r to those of the other i n l e t s of the B r i t i s h Columbia coast.  They are elongated, narrow waterways with steep,  roughly p a r a l l e l , s i d e s .  The p r i n c i p a l basins of each of the  i n l e t s i n the system are p a r t i a l l y separated from the a d j o i n i n g basins, or channels by s i l l s .  The depths of these s i l l s subdivide  the i n l e t s of the system into two groups.  The largest group  containing Princess Louisa, Sechelt and Narrows Inlets  have"shallow"  s i l l s , while Jervis I n l e t i s separated from Georgia S t r a i t by a "deep" s i l l . The difference between a shallow and deep s i l l i s somewhat arbitrary.  In t h i s account a shallow s i l l i s one which confines  the t i d a l flow to such a degree that the t i d e water enters, and leaves the i n l e t i n a turbulent j e t . The flow through the channel of a shallow s i l l e d i n l e t i s at any one time, u n i d i r e c t i o n a l , e i t h e r into the i n l e t or out.  entrance  predominantly  A deep s i l l allows  the tide water to enter and leave the i n l e t without destroying, to any appreciable degree, the v e r t i c a l s t r a t i f i c a t i o n i n the water column.  The flow through the entrance channel of a deep s i l l e d  i n l e t can be e i t h e r i n t o the i n l e t , out of the i n l e t or i n both directions at the same time.  Since there i s no s i l l separating the  basins of Sechelt and Salmon I n l e t s , the l a t t e r i s treated as a branch of the former, and not as a separate i n l e t .  2 The purpose of this work was to i n v e s t i g a t e the c i r c u l a t i o n pattern i n the J e r v i s system of i n l e t s , s t r e s s i n g seasonal changes and the i n t e r a c t i o n between the interconnecting basins.  Although  considerable data had been c o l l e c t e d before this programme was started i t was l i m i t e d to J e r v i s I n l e t .  Thus a new programme with  the above purpose i n mind was begun i n 1961.  The data c o l l e c t i n g  consisted of sampling the water at d i s c r e t e depths at various stations (figure 1) throughout the i n l e t system.  Atlas water  sampling b o t t l e s were used i n conjunction with Richter & Wiese, and Yoshino Keike reversing thermometers.  The s a l i n i t y of the water  samples was determined by the Mohr s i l v e r n i t r a t e t i t r a t i o n method ( S t r i c k l a n d and Parsons, i960) and the dissolved oxygen content of the water was determined by the Winkler method ( S t r i c k l a n d and Parsons, i960). Previous i n v e s t i g a t o r s notably T u l l y (1949)> P r i t c h a r d (1952), Pickard and T r i t e s (l956)» Pickard ( I 9 6 I ) , and G i l m a r t i n (1962) have discussed the general features of the c o a s t a l i n l e t s .  Because of  land drainage and p r e c i p i t a t i o n , a l l the i n l e t s possess a t h i n surface layer of brackish water.  This l o w - s a l i n i t y surface layer  "flows seaward, gaining i n volume by entrainment of s a l i n e water from below as i t does so and gaining i n speed as i t approaches the i n l e t mouth." (Pickard, 1961)  To compensate f o r t h i s l o s s of water  from the i n l e t a subsurface inflow i s generated.  This "estuarine  c i r c u l a t i o n " of surface outflow and subsurface i n f l o w , however, i s not possible i n the shallow s i l l e d i n l e t s .  The c i r c u l a t i o n pattern  i n the shallow s i l l e d Inlets i s determined by the nature of the t i d a l j e t and i t s i n t e r a c t i o n with the water i n the i n l e t basin.  A cir-  c u l a t i o n pattern for,these i n l e t s i s proposed l a t e r i n t h i s account.  3 The work of previous investigators also raised some unanswered questions.  For example; Carter (1934) reported that the deep water  i n Princess Louisa Inlet was completely devoid of dissolved oxygen, but  Pickard ( l 9 6 l ) reported 1.7 m l / l of dissolved oxygen i n May 1952  and 3«4 m l / l i n June I960, i n the same body of water. of  Between each  these v i s i t s to the i n l e t , highly oxygenated water must have  intruded to the deep zone, but the details of the process were not understood.  Another problem which was studied i n the present  programme concerns the oxygen d i s t r i b u t i o n i n Sechelt and Jervis Inlets.  In June 1957 an oxygen minimum was found at mid-depths i n  Sechelt and Salmon Inlets (Pickard, 1 9 6 l ) , but i n June 1961 no minimum could be found at mid-depths.  However, the deep water i n  the .inlets contained about 3 m l / l less dissolved oxygen than i n 1957* Thus the c i r c u l a t i o n pattern i n the i n l e t is able to support a middepth oxygen minimum at one time, but some time l a t e r the lowest oxygen concentration i s found i n the deep water.  The data from a l l  cruises to Jervis Inlet have revealed a region of water containing less than 2 m l / l of dissolved oxygen.  Sometimes this water forms a  mid-depth oxygen minimum, but at other times i t forms a deep layer of  "low-oxygen" water.  The changes i n dissolved oxygen d i s t r i b u t i o n  i n these inlets are accompanied by changes i n the temperature and s a l i n i t y d i s t r i b u t i o n , but the l a t t e r are not as spectacular. Because the current structure i n the shallow s i l l e d inlets is markedly different from that i n the deep s i l l e d i n l e t these two categories are treated separately.  (Jervis)  It has also been  deemed advisable to preface the discussion of the data with some of the conclusions of the study.  It i s hoped that this w i l l give the  reader an overall picture before the detailed data supporting the conclusions is given.  II.  SHALLOW SILLED INLETS  Proposed Current Pattern Princess Louisa, Sechelt, and Narrows I n l e t s have shallow entrance s i l l s which r e s t r i c t the movement of water i n and out o f these basins to the top few metres of the water column. The d i s t r i b u t i o n s of the oceanographic  v a r i a b l e s , temperature,  and oxygen, are s i m i l a r i n a l l three i n l e t s .  salinity  I t i s proposed that  the c i r c u l a t i o n s responsible f o r these d i s t r i b u t i o n s are also s i m i l a r , because of the shallow s i l l s .  A c i r c u l a t i o n pattern common to a l l  three shallow s i l l e d i n l e t s i s proposed below. The important feature of these i n l e t s i s the exchange of tide water.  The physical r e s t r i c t i o n s of the s i l l force the f l o o d t i d e to  enter the i n l e t as a v i o l e n t l y turbulent j e t . This j e t , downstream of the s i l l , spreads out by e n t r a i n i n g some of the surrounding water. This phenomenon i s common to a l l "free" turbulent j e t s , (Rouse, 1959)• The word "free" implies that there i s no s o l i d boundary i n the f l u i d which affects the j e t . A free j e t may be v i s u a l i z e d by i n j e c t i n g ink with a hypodermic needle i n t o a large tank of water.  Although  this  i d e a l i z e d state i s not present i n the i n l e t the j e t w i l l spread out u n t i l i t comes i n contact with the surrounding channel.  Another  property of a turbulent j e t i s that i t w i l l tend to " s t i c k " to any s o l i d boundary with which i t comes i n t o contact (Newman, 1 9 6 l ) .  Thus,  the flood t i d e j e t which i s i n contact with the bottom at the s i l l w i l l tend to "hug" the bottom u n t i l buoyancy forces, inherent i n the density s t r a t i f i c a t i o n i n the i n l e t , force i t up. The j e t w i l l produce a homogeneous mass of water near the mouth of the i n l e t .  The depth of t h i s mass w i l l be much greater  than the s i l l depth due to the j e t "hugging" the bottom, and the volume w i l l be greater than the actual volume of flood water because of entrainment. Near the s i l l the force of the t i d a l j e t w i l l be great enough to erode the surface layer, but as the turbulence dies out the f l o o d water w i l l sink under the surface l a y e r .  This  phenomenon gives r i s e to a v i s i b l e t i d e - l i n e or " j u n k - l i n e " where f l o a t i n g debris c o l l e c t s . The water of the f l o o d t i d e originates i n the surface water outside the i n l e t , and therefore the density of t h i s water w i l l vary during the year r e f l e c t i n g the changes i n a i r temperature and surface runoff.  Because of the physical d i f f i c u l t i e s  no water samples have  been taken from the t i d a l j e t as i t crosses the s i l l , but data from the  surface layer j u s t outside the s i l l i n d i c a t e that the average  density of the flood t i d e water varies as shown i n f i g u r e 2. This curve shows a maximum density i n l a t e winter, and a minimum i n early summer.  There  w i l l undoubtedly be many small f l u c t u a t i o n s i n t h i s curve, but they w i l l not a l t e r the general decrease i n spring and r i s e i n the autumn. the  The value of  o  I II M  M  i J  TIME  i  • S  i  i  N  Figure 2. Average annual v a r i a t i o n of the flood t i d e water.density.  maximum i n l a t e winter w i l l vary from year to year as w i l l the  minimum, depending on seasonal temperatures and r a i n f a l l . For the  s i m p l i c i t y i n describing the e f f e c t of the t i d a l flow on  i n l e t , suppose that the temperature, s a l i n i t y and dissolved  oxygen of the water i n the i n l e t below the runoff layer are completely uniform.  Assume further that the density of the f l o o d  6  t i d e water i s at a maximum f o r the year, and i s j u s t about to s t a r t decreasing due to s p r i n g runoff and temperature conditions.  Figure 3  depicts the conditions i n the i n l e t when the water of the f l o o d t i d e i s less dense than the homogeneous indigenous water below the • surface l a y e r .  Figure 3« Hypothetical schema of a shallow s i l l i n l e t f o l l o w i n g a f l o o d t i d e i n s p r i n g . The l e t t e r s are explained i n the t e x t . Layer A i s the low density surface layer i n the i n l e t formed by runoff and p r e c i p i t a t i o n . Water mass B i s the homogeneous mass of f l o o d t i d e water, and C represents water i n the i n l e t below the surface layer.  Water mass C i s homogeneous but denser than water mass B.  Because the density of the f l o o d water (B) i s greater than the density of water i n the surface l a y e r (A), water mass B l i e s under the surface l a y e r A.  The mixing due to the t i d a l j e t destroys the  surface l a y e r near the s i l l .  V e r t i c a l density p r o f i l e s f o r positions  near the mouth and head are shown on the r i g h t i n f'igmre 3*  It is  c l e a r l y seen i n these p r o f i l e s that the density of the water at D and F i s less than at G and E.  Thus a h o r i z o n t a l density and pressure  gradient i s created which r e s u l t s i n h o r i z o n t a l flow.  The water at  G and E w i l l flow toward the mouth under the t i d e water (arrow I  7 f i g u r e 3) while the t i d e water w i l l flow up-inlet,, (arrow between the surface l a y e r and flow I.  II),  These two currents create a  shear between two water masses of d i f f e r e n t c h a r a c t e r i s t i c s , and the tendency w i l l be f o r these water masses to exchange t h e i r characteri s t i c s and become homogeneous.  Flow in the  Surface  This process i s depicted i n figure 4»  Layers  Salinity  Profile  Figure 4. Changes i n the v e r t i c a l s a l i n i t y gradient when subjected to the i n d i c a t e d shear. The p r o f i l e l a b e l l e d 1 represents the i d e a l i z e d s a l i n i t y d i s t r i b u t i o n before any shear takes place between the three l a y e r s , ( i . e . layers A, B and C of f i g u r e 3)«  P r o f i l e s 2 and 3 represent  the s a l i n i t y d i s t r i b u t i o n a f t e r the shear has been a c t i n g f o r some time, ( T r i t e s , 1955)' Arrows I and II  represent the same flows as i n  f i g u r e 3» As long as the density of the f l o o d t i d e becomes progressively less the mechanism just described w i l l p r e v a i l .  Also, as the density  difference between the flood water and the deep water becomes greater, the density s t r a t i f i c a t i o n i n the upper layers of the i n l e t becomes more pronounced.  The l a y e r of water i n the i n l e t which i s a f f e c t e d  8 by the flood t i d e water w i l l become t h i c k e r , because of the continual exchange effected by the shear between flow I and I I (figure 3 and 4)•  However, as the density gradient i n the i n l e t  becomes greater, t h i s shear w i l l tend to be confined, which puts a lower bound on the depth of the affected region. which may  Another f a c t o r  tend to d i c t a t e the depth of t h i s layer i s the behaviour  of the t i d a l j e t .  I f the density of the t i d e water was  exactly  the  same as a l l the water i n the i n l e t , the t i d a l j e t would flow i n t o the i n l e t unaffected by buoyancy forces.  The  l i m i t s of such a j e t  w i l l be c a l l e d the "natural" l i m i t s .  These "natural" l i m i t s  determined by the p h y s i c a l properties  of the j e t and the surrounding  channel are changed by a density s t r a t i f i c a t i o n i n the i n l e t .  But  the j e t w i l l tend to destroy t h i s s t r a t i f i c a t i o n and regain i t s "natural" l i m i t s .  Thus the lower bound on the region affected  the j e t w i l l depend on the density s t r a t i f i c a t i o n i n the i n l e t  by and  the "natural" l i m i t s of the t i d a l j e t . The  flow depicted i n f i g u r e 3, as mentioned, w i l l continue as  long as the density of the flood t i d e water i s less than that of a l l the water i n the i n l e t below the surface runoff layer.  In the l a t e  summer," autumn, and early winter the density of the flood water i s increasing (figure 2) and the conditions those shown i n figure 5.  i n the i n l e t are changed to  In the v e r t i c a l density p r o f i l e s at the  r i g h t of the f i g u r e i t i s seen that the density of the water at P and I) i s greater than that at G and E.  The h o r i z o n t a l pressure  gradient r e s u l t i n g w i l l tend to push the t i d e water (B) u p - i n l e t (arrow I i ) at an intermediate depth.  This mass of water flowing i n  at mid-depth w i l l l i f t up the water above the i n t r u s i o n (arrow I ) . This water w i l l tend to j o i n the outflow of the surface l a y e r .  Now  9  Figure 5* Hypothetical schema of a shallow s i l l i n l e t f o l l o w i n g a f l o o d t i d e i n autumn. The l e t t e r s are explained i n the text. the region of greatest shear i s moved downwards, which w i l l force an exchange of heat and s a l t with deeper layers than before. e f f e c t s a deepening of the intermediate l a y e r .  This  As the season  progresses and the density of the tide water increases, the t h i c k ness of the region a f f e c t e d by the f l o o d tide water increases, but the density difference between the intermediate and deep layers becomes l e s s .  a  The stages of t h i s process are shown i n f i g u r e 6.  b  c  d  e  Figure 6. Changes i n the s a l i n i t y p r o f i l e i n a shallow s i l l i n l e t as the density of the f l o o d t i d e increases i n the autumn. The s i n k i n g of the f l o o d tide water produces f l u s h i n g by r e p l a c i n g the indigenous i n l e t water at the depth of s i n k i n g .  The  indigenous water i s pushed up and towards the head of the i n l e t .  10  The depth to which f l u s h i n g proceeds w i l l become greater as the density of the flood water increases.  During most years the f l o o d  t i d e density does not increase enough to replace the bottom water. In t h i s case the density structure proceeds to the s t a t e shown i n f i g u r e 6c or 6d.  Occasionally f l u s h i n g of the bottom water does  occur leaving a density p r o f i l e s i m i l a r to that shown i n f i g u r e  6e.  The greatest depth of the f l u s h i n g occurs at the time of greatest density of the f l o o d t i d e water, u s u a l l y i n l a t e winter.  Modifi-  cations to the v e r t i c a l density structure produced by spring conditions are confined to the upper layers of the i n l e t , and any density structure l e f t by incomplete f l u s h i n g i n the deep regions or 6d)  ( f i g u r e 6c  w i l l remain throughout the next year. The d i s t r i b u t i o n of dissolved oxygen i n the shallow  silled  i n l e t s presents some regular features complementary to the mechanisms j u s t discussed.  The f l o o d t i d e water originates i n the oxygen r i c h  surface layers outside the i n l e t , and i s v i o l e n t l y mixed i n the presence of a i r as i t enters the i n l e t .  These factors combine to  produce a water mass generally r i c h i n oxygen.  The region i n the  i n l e t most strongly influenced by the f l o o d t i d e water w i l l e x h i b i t high oxygen values.  Between f l u s h i n g s , the region below t h i s  influence i s cut o f f from sources of oxygen other than the small amount that diffuses down from the upper l a y e r s .  This deep,  r e l a t i v e l y "stagnant" zone displays a low or d e c l i n i n g oxygen concentration.  This i s a t t r i b u t e d to oxygen demand i n the water  r e s u l t i n g from oxidation of d e t r i t a l material f a l l i n g from the surface l a y e r s .  This e s s e n t i a l l y two layer d i s t r i b u t i o n i s modified  by f l u s h i n g , and by b i o l o g i c a l production and consumption of oxygen i n the upper l a y e r s .  These modifications w i l l be discussed as they  11 appear i n the data, which are given i n the f o l l o w i n g s e c t i o n s .  Princess Louisa I n l e t Princess Louisa I n l e t opens into J e r v i s I n l e t at 50°9.7' N 133°51« W on the north-east shore of Queen's Reach.  It i s  roughly four miles long and one-half mile wide, with an average depth of about 120 metres.  The plan and l o n g i t u d i n a l p r o f i l e of the  i n l e t are shown i n f i g u r e 7•  0 -50 ,100  1-150 Metres  Figure 7« Princess Louisa I n l e t . As mentioned previously, a shallow s i l l at the mouth r e s t r i c t s communication with J e r v i s I n l e t .  The threshold depth of the s i l l  v a r i e s from about 6 to 11 metres depending on the s t a t e of the t i d e . The width of the channel at i t s shallowest point i s 60 metres.  The  mountainous t e r r a i n surrounding the i n l e t produces very steep sides, both above and below the water l i n e .  These walls tend to i s o l a t e the  i n l e t from high winds, r e s u l t i n g i n a calm water surface and the absence of appreciable wind mixing.  The data obtained from t h i s  i n l e t during 1962 and early 1963 are discussed below i n r e l a t i o n to  12 the mechanisms proposed p r e v i o u s l y . March 1962 The f i r s t c r u i s e of the s e r i e s , i n March 1962, revealed a water mass with only small v a r i a t i o n s i n temperature, s a l i n i t y , and dissolved oxygen.  Although the greatest range of observed values  wasAT=0.47 C°AS-0.46  and A,0 =1.29 m l / l some h o r i z o n t a l 2  gradients were observed, as shown i n f i g u r e 8.  Figure 8.  Longitudinal p r o f i l e s of temperature, s a l i n i t y and dissolved oxygen i n Princess Louisa I n l e t , f o r March, 1962.  The deep water at s t a t i o n s 1 and 2 characterized by high dissolved oxygen, low temperature and high s a l i n i t y i s noticeably d i f f e r e n t from the intermediate water at a l l three s t a t i o n s characterized by r e l a t i v e l y high temperature, low s a l i n i t y , and low oxygen.  There  seems l i t t l e doubt from t h i s and the shape of the i s o p l e t h s that the former water mass i s new to the i n l e t .  Thus the i n l e t i s i n the  process of being flushed r i g h t to the bottom by the s i n k i n g of the high density f l o o d t i d e water. May  1962 The v a r i a t i o n s i n May, of temperature, s a l i n i t y and dissolved  oxygen i n the v e r t i c a l d i r e c t i o n are much greater than the  13 horizontal variations.  For t h i s reason the h o r i z o n t a l v a r i a t i o n  i s neglected and the i n l e t i s treated as a ' f e g l e column of water.  The curves i n f i g u r e 9 represent the average v a r i a t i o n  with depth of temperature, s a l i n i t y and oxygen f o r March and May 1962.  The p r o f i l e s f o r March show an almost uniform body of water,  as mentioned previously, but the p r o f i l e s f o r May reveal the effects of a decrease i n t i d e water density due to spring runoff and temperature  conditions.  I5(H  Temperature  *C.  Salinity % .  Oxygen  ml/l.  Figure 9» Average v e r t i c a l temperature, s a l i n i t y and oxygen p r o f i l e s f o r March and May 1962« The s a l i n i t y p r o f i l e shows three d i s t i n c t layers; the top r e l a t i v e l y fresh 5 metres (layer I f i g u r e 9)» the intermediate layer to 75 metres (layer I i ) , and the deep homogeneous layer (layer I I I ) . The steep l i n e a r gradients i n layer I I are a t t r i b u t e d to the shear between the up i n l e t flow of tide water and the down i n l e t flow, at mid-depth, as proposed on page6 and i n figure 3« These gradients are very s i m i l a r to the proposed p r o f i l e number 3 i n figure 4« I t i s i n t e r e s t i n g to note that the surface layer (layer I) o f r e l a t i v e l y fresh water e x h i b i t s no large temperature gradient  corresponding to the large s a l i n i t y gradient i n the l a y e r .  This  appears to be quite an uncommon occurrence and i s discussed more f u l l y on page 17. The s a l i n i t y , and hence density, of the deep homogeneous zone (layer I I I ) i s greater i n May than i n March.  This could only  happen i f the flood t i d e continued to increase i n density a f t e r the March c r u i s e , thus prolonging the f l u s h i n g .  The lower dissolved  oxygen content i n t h i s layer i s a t t r i b u t e d to oxygen demand i n the water, but i t may be an e f f e c t of continued turnover a f t e r the March c r u i s e . July  1962 Figure 10 shows the average v e r t i c a l d i s t r i b u t i o n s of  temperature, s a l i n i t y , and oxygen f o r J u l y 1962 compared with those f o r May 1962.  The surface, intermediate, and deep layers are  present as i n May, but between the l a t t e r two there i s a new  layer  (layer I l a ) of very steep gradients i n temperature and s a l i n i t y . The depth at which the deep homogeneous zone begins has not changed since May.  This depth of about 75 metres appears to represent a  lower boundary f o r l a y e r I I and I l a when the density of the flood water i s decreasing. on page 8.  A reason f o r t h i s lower boundary was proposed  The large gradients i n l a y e r I l a are a r e s u l t of a  large density drop i n the water of the f l o o d t i d e .  There i s not a  l i n e a r gradient through layers I I and I l a because the t i d a l j e t has enough energy to erode large gradients only to a c e r t a i n depth; about 40 to 50 metres i n t h i s case. The high dissolved oxygen content above 75 metres i n May  and  J u l y i s a t t r i b u t e d to production of oxygen by phytoplankton i n the upper l a y e r s .  The phytoplankton blooms occur i n both Princess Louisa  and J e r v i s I n l e t s .  The high oxygen concentration i n the upper  15 layers of Jervis Inlet appear In layer II i n Princess  o  u  ,  Salinity  y  %  0  Figure 10. Average v e r t i c a l temperature, s a l i n i t y and oxygen p r o f i l e s for Princess Louisa Inlet during May and July 1962. Louisa Inlet by virtue of the flood t i d e .  The oxygen curve for  July shows a sharp change i n gradient at 40 metres.  This level  coincides with the bottom of layer II which i s the l i m i t of influence of the t i d a l j e t .  Below this depth the oxygen content  i s not being increased by phytoplankton production or by renewal from the tide, but is being depleted continually because of the oxygen demand i n the water. zone (layer III) since May.  The oxygen concentration i n the deep  is 2.3 m l / l i n July which is a decrease of 1.6 m l / l  16 October 1962 The average v e r t i c a l p r o f i l e s f o r J u l y and October are compared i n figure 11.  The four d i s t i n c t layers are s t i l l present,  but the water i n l a y e r I has l o s t a considerable amount of heat while gaining s a l t .  This layer i s also t h i c k e r . The increase i n  density of the water i n layer I I i n d i c a t e s that the density of the flood t i d e water i s i n c r e a s i n g . Because the density of the t i d e water i s i n c r e a s i n g the current pattern i n the i n l e t changes to that depicted i n f i g u r e 5 i  a  n  d discussed on page 9 »  2  _i  4  6 1  8 1  w 01  «  100  Temperature  Oxygen ml^  *C  150  12  16  1—  CO  20 1  9 0  01  Salinity  2 I 00  150  %.  July  October  Figure 11. Average v e r t i c a l temperature, s a l i n i t y and oxygen p r o f i l e s f o r J u l y and October 1962. The f l o o d tide water now flows up i n l e t at an intermediate depth instead of j u s t under the surface l a y e r as i t did when the t i d e  i  17 water was decreasing i n density.  The increased exchange with the  deep region r e s u l t i n g from the s i n k i n g t i d e water increases the depths of layers I I and H a . In October, the surface l a y e r of r e l a t i v e l y f r e s h water (layer I ) exhibits a d i s t i n c t temperature gradient (figure l l ) .  It  was noticed (page 14) that there was no such temperature gradient i n the surface layer i n May 1962. (figure 10). radiation.  This was a l s o true i n J u l y 1962  The main source of heat i n the surface layer i s s o l a r This heat which i s absorbed by the water i s e i t h e r  radiated back or i s c a r r i e d out of the i n l e t with the surface runoff.  The downward transport of heat i s l i m i t e d by the s t a b i l i t y of  the surface l a y e r .  Thus i f there i s more heat per u n i t volume of  water i n the surface l a y e r than i n the underlying l a y e r s , i t must mean that the surface l a y e r i s gaining more heat by r a d i a t i o n than i t i s l o s i n g by back r a d i a t i o n or advection.  Also, i f there i s  less heat i n the surface l a y e r , i t must be l o s i n g heat f a s t e r by back r a d i a t i o n and advection than i t i s gaining by d i r e c t r a d i a t i o n . I f , as i n May and J u l y , there i s no d i f f e r e n c e i n heat content between the surface layer and the water below there must be a balance between heat- gain and l o s s .  In t h i s case the transport of  heat through the large density gradient of the surface layer becomes important. November 1962 The average v e r t i c a l p r o f i l e s f o r October and November are shown i n f i g u r e 12.  The v e r t i c a l d i s t r i b u t i o n reveals a continued  erosion of layer I l a , and a f u r t h e r loss of heat accompanied by a gain of s a l t i n l a y e r I I . These changes are brought about by the continuation of the processes produced by an increasing f l o o d t i d e  18  density.  October November  Figure 12. Average v e r t i c a l p r o f i l e s f o r P r i n c e s s Louisa d u r i n g October and November 1962.  Inlet  January I963 A comparison of the November I962 and January 1963 p r o f i l e s ( f i g u r e 13) i n d i c a t e s f l o o d t i d e water. characteristics  F i g u r e 13•  a continued i n c r e a s e i n the d e n s i t y of  Layer II which r e f l e c t s  shows a l a r g e heat l o s s ,  the  the changes i n f l o o d  tide  but a r e l a t i v e l y minor gain  Average v e r t i c a l p r o f i l e s f o r P r i n c e s s Louisa d u r i n g November 1962 and January 1963«  Inlet  19 in salinity.  An i n t e r e s t i n g feature of the temperature p r o f i l e f o r  January i s the maximum j u s t below the surface runoff l a y e r ( A ) . The f l o o d t i d e water which evidently has a lower temperature has sunk below t h i s region l e a v i n g i t with the higher temperature i t had e a r l i e r i n the year. February 1963 The February p r o f i l e s (figure 14) show two d i s t i n c t , nearly uniform, regions i n l a y e r I I with a s l i g h t oxygen minimum between them.  These two regions are l a b e l l e d l i b and l i e i n f i g u r e 14*  A f t e r the cruise i n January the f l o o d t i d e water continued to sink to the bottom of l a y e r I I and flow up i n l e t .  The shear created by  t h i s flow forced an exchange i n the properties between l a y e r I I and layer I I I .  This continuous exchange increased the depth of the  region affected by the f l o o d t i d e water (layer I I ) .  The p r o f i l e s  slowly changed u n t i l they appeared as shown by the dotted l i n e s . Then suddenly the density of the f l o o d t i d e water decreased and f l o a t e d near the surface.  This sudden change i n density created the  steep gradients at 50 metres (figure 14)• The change i n f l o o d water density was accompanied by a drop i n both temperature and s a l i n i t y . 0  2  -1—  60-  100-  150  [ Temperature •( January  Salinity  Oxygen ml I  February  Figure 14. Average v e r t i c a l p r o f i l e s f o r Princess Louisa I n l e t during January and February 1963*  20  A drop i n temperature i n c r e a s e s t h e d e n s i t y h u t a drop i n s a l i n i t y decreases the d e n s i t y .  I t i s assumed t h a t the e f f e c t o f t h e  s a l i n i t y change i s g r e a t e r than the e f f e c t o f t h e temperature change.  The oxygen minimum l i e s j u s t below t h e s t e e p g r a d i e n t s a t  50 metres, and t h e r e f o r e between t h e l a y e r s i n f l u e n c e d by the t i d e water. March 1 9 6 3 The p r o f i l e s ( f i g u r e 1 5 ) i n d i c a t e t h a t the d e n s i t y o f the f l o o d t i d e water has decreased s i n c e F e b r u a r y .  The t i d a l j e t has  eroded the sharp g r a d i e n t s a t 50 metres and extended i t s i n f l u e n c e to 8 5 metres.  Changes below t h i s l e v e l a r e v e r y s l i g h t , but g r e a t e r  than p r e v i o u s l y .  Deep water changes a r e d i s c u s s e d  i n t h e next  section.  February  —  March  F i g u r e 1 5 . Average v e r t i c a l p r o f i l e s f o r P r i n c e s s L o u i s a d u r i n g F e b r u a r y and March I 9 6 3 .  Inlet  The Deep Layer In t h e p r e c e d i n g d i s c u s s i o n v e r y l i t t l e was s a i d about the changes o f temperature and s a l i n i t y o c c u r r i n g i n t h e deep  21 homogeneous water.  Figure 16 shows the changes i n temperature,  s a l i n i t y , and oxygen i n t h i s layer throughout the year. A l l observations taken i n the deep layer were p l o t t e d on the same graph and the best curves drawn.  Because the ordinate scales are greatly  expanded the assumed error range f o r each v a r i a b l e i s shown a l s o . These error ranges apply to each observation s i n g l e competent observer.  i n d i v i d u a l l y , and to a  The errors of measurement when observing  the same water mass at d i f f e r e n t times and by d i f f e r e n t observers i s not estimated.  Thus the accuracy i s assumed to be w i t h i n the l i m i t s  shown i n f i g u r e 16, but the p r e c i s i o n i s not known. However, i t i s possible to draw quite smooth d e f i n i t e curves through the p l o t t e d points, and i t i s assumed that the error between cruises and observers i s not appreciably i n d i v i d u a l measurement.  d i f f e r e n t from the errors of an  Thus the p r e c i s i o n of the observations i s  assumed to be w i t h i n the same l i m i t s of error as the accuracy of the  observations.  1  i i—i—i—i—i—i—i—i—i—i—i—i—i—i—III  J  M  M  J  S  N  —  J M M 1962 -*4—1963  •  TIME  Figure 16. Temperature, s a l i n i t y , and oxygen concentration i n the deep layer of Princess Louisa I n l e t plotted against time.  22 The s a l i n i t y curve shows a sharp r i s e between March and May 1962 i n d i c a t i n g the continued renewal of the deep water a f t e r the March c r u i s e .  From May to the f o l l o w i n g February the s a l i n i t y  decreased at a f a i r l y uniform rate from a high of 28.67 to 28.51$« i n February I963.  From February to March I963 the s a l i n i t y dropped  sharply to 28.38$« .  This i s a drop of 0.13$» i n a month as  compared to a drop of 0.16$« i n the previous nine months. The temperature curve also shows a sharp r i s e between March and May 1962.  This temperature r i s e which i s accompanied by a  s a l i n i t y r i s e i s a t t r i b u t e d to continued turnover between March and May.  From May I962 to February 1963 the temperature r i s e s uniformly  from 7• 56>  0  C i n May to 7*66  0  C i n February.  From February to March  1963 there i s a r i s e of 0.07 C°. A f t e r the density of the flood t i d e water s t a r t e d to decrease i n the spring of 1962 the deep homogeneous layer was e f f e c t i v e l y cut o f f from the upper layers i n the i n l e t .  The gradients of temperature  and s a l i n i t y were such, throughout the year, that d i f f u s i o n would slowly decrease the s a l i n i t y and increase the temperature of the deep water, as observed between May 1962 and February 1963*  The rapid  r i s e of temperature and drop i n s a l i n i t y between February and March 1963 i s thought to be due to increased d i f f u s i o n during t h i s time. This increased d i f f u s i o n i s a t t r i b u t e d to the s i n k i n g of the f l o o d t i d e water which would " s t i r up" the deep water to a greater degree than when the flood t i d e f l o a t s near the surface. The oxygen curve i n f i g u r e 16 shows a rapid decling from 3.9 m l / l i n May 1962 to 0.5 m l / l i n January I963.  This r a p i d  decline i s a t t r i b u t e d to the oxygen demand of d e t r i t a l m a t e r i a l .  23 A f t e r January I963  oxygen content remained almost  constant.  This i s thought to be a r e s u l t of the increased exchange between the deep and intermediate waters caused by the s i n k i n g f l o o d t i d e water. The changes of a l l three v a r i a b l e s between May I962 and January 1963 appear to be a r e s u l t of the r e l a t i v e i s o l a t i o n of the deep layer during these months. When the density of the tide water increases i n the f a l l and winter the layer influenced by the t i d a l jet becomes t h i c k e r and exchange with the deep layer increases.  This  increased exchange between the deep and intermediate layers increases the rate of s a l i n i t y decline and temperature gain, and decreases the rate of oxygen l o s s . Figure 17 i s the same as f i g u r e 2 with the a d d i t i o n of a l i n e representing the change of density i n the deep l a y e r . s a l i n i t y i s the most important f a c t o r i n determining  Because  density this  l i n e should be s i m i l a r to the change of s a l i n i t y with time as shown i n f i g u r e 16. However, the ordinate scale i n f i g u r e 16 i s greatly expanded and the s a l i n i t y curve appears as a s t r a i g h t l i n e i n figure I?•  Because of d i f f u s i o n the density of the deep water w i l l  ^•Density  of  the water in the  deep  layer  Time  Figure 17* Comparison between the v a r i a t i o n of flood t i d e density and deep water density with time.  24 slowly decrease as observed.  The density of the f l o o d t i d e water  w i l l vary i n the general manner shown.  I t i s i n e v i t a b l e that the  density of the t i d e water w i l l someday become greater than the density of the deep water.  When t h i s occurs f l u s h i n g w i l l take  place, as i t d i d i n the s p r i n g of 1962.  However, the maximum  density of the flood t i d e water i s not the same each year, and the i n t e r v a l between each f l u s h i n g i s unpredictable.  An abnormally high  t i d e water density w i l l cause f l u s h i n g sooner than i f normal conditions p r e v a i l e d . In order to predict the time of deep water f l u s h i n g i t i s necessary to know when the density of the f l o o d t i d e water w i l l be greater than the density of a l l the water i n the i n l e t .  The annual  v a r i a t i o n of t i d e water density proposed i n f i g u r e 2 i s not accurate enough f o r this purpose.  Short term v a r i a t i o n s i n runoff, and  current patterns i n J e r v i s I n l e t both a f f e c t the t i d e water density. These factors are unpredictable on a long term b a s i s .  However, i f  the density of the f l o o d t i d e water could be compared with the density structure i n the i n l e t i t would be possible to predict to what depth the flood water would sink when i t entered the i n l e t . Possibly the caretaker at the camp s i t u a t e d at the mouth of Princess Louisa I n l e t could be persuaded to take samples of the flood t i d e water.  The density of these samples could be c o r r e l a t e d  with meteorological data, s p e c i f i c a l l y a i r temperature and r a i n f a l l . Changes i n the current pattern and v e r t i c a l density structure i n J e r v i s I n l e t may be predictable from wind vector data.  It is  proposed l a t e r i n t h i s thesis that an up i n l e t wind i n J e r v i s increases the thickness of the surface l a y e r .  This may decrease the  density of the t i d e water entering Princess Louisa.  A prolonged  FIGURE  T H E  S E C H E L T  18  I N L E T  S Y S T E M  25  down i n l e t wind may b r i n g denser water nearer the surface of J e r v i s , which would i n turn increase the density of the f l o o d t i d e water of Princess Louisa.  Thus there may be a c o r r e l a t i o n between the wind  vector i n J e r v i s and the f l o o d t i d e water density entering Princess Louisa I n l e t .  The v a r i a t i o n of deep water s a l i n i t y (oC density) i n  Princess Louisa I n l e t f o r 1962  i s shown i n f i g u r e 16.  Because the  deep water was not flushed i n the winter of 1962-63 t h i s curve only represents part of the s a l i n i t y v a r i a t i o n between f l u s h i n g s . I t w i l l be necessary to monitor the density of the deep water u n t i l the next f l u s h i n g to understand the complete c y c l e .  The decrease i n  s a l i n i t y of the deep water w i l l depend on the v e r t i c a l gradient i n the basin.  During 1962  salinity  the s a l i n i t y of the deep l a y e r  was nearly uniform and the decrease throughout the year was as shown i n f i g u r e 16. profiles,  In 1963  a steeper s a l i n i t y gradient during the year.  of the deep water may  1963  there w i l l be, judging from the March  decrease more r a p i d l y i n 1963  The  density  than i n  1962.  Sechelt I n l e t System The plan of the Sechelt I n l e t system and the l o n g i t u d i n a l p r o f i l e s of the basins are shown i n f i g u r e 18.  The system i s  comprised of Sechelt, Salmon, and Narrows I n l e t s .  The water i n the  system communicates with that of J e r v i s over a shallow, s i l l at Skookumchuck Narrows.  In the d i s c u s s i o n below Sechelt and Salmon  I n l e t s are treated as one i n l e t .  The t i p of Sechelt extending from  Nine Mile Point to Porpoise Bay i s neglected, because i t receives  26 only  a small proportion  Inlet  Narrows  from S e c h e l t The silled  is treated I n l e t by  oxygen b e i n g v e r y  The  g r e a t e r s i z e of  horizontal  the  July  separately  i n the  to  1961  proposed e a r l i e r f o r  distributions  of  is  separated  the  shallow  temperature,  L o u i s a and  e x i s t , and  the  inlet  can  salinity  Sechelt  - Salmon system a l l o w s  Inlets.  larger  not  be  treated  as  of  the  data i s  given  a l l times.  c r u i s e by  cruise  discussion  salinity  a v e r a g e v e r t i c a l t e m p e r a t u r e and are  dissolved  given  oxygen. are  variables  not  are  temperature, column i n t o  in figure The  shown b e c a u s e  so  layer  salinity  three  i s due  radiation, inlet  and  high  The  the  65 the  salinity  top  horizontal  greater  heat.  layer  p r o f i l e of  temperature  gradients  of  and these  v e r t i c a l gradients.  ( l a y e r I)  the  high  by  temperature from d i r e c t  of  The  water  extending  is characterized  The  for  to  5  relatively this  solar  back r a d i a t i o n  and  a d v e c t i o n out  intermediate  layer  (layer II)  lying  most s t r o n g l y  influenced  by  The  metres i s the  region  t i d e water.  i n layer  the  i n f l u x of heat,  o f h e a t by  flood  to  profiles  longitudinal  p r o f i l e s of  w a t e r and  temperature.  of s e n s i b l e  of  the  the  salinity  d i s t r i b u t i o n c l e a r l y divides  layers.  than l o s s  b e t w e e n 5 and character  and to  with  s m a l l i n comparison  and  salinity  19  longitudinal  metres i s formed from r u n o f f  ture  i t s basin  system.  1961  July  the  the  p r o p o s e d mechanisms i n m i n d .  The  low  enters  sill.  Sechelt  column o f water a t following  since  similar i n Princess  the  gradients  The with  runoff, which  a shallow  inlets results  single  the  c i r c u l a t i o n pattern  and  a  of  II are  The  l i n e a r gradients  attributed  to  the  shear  of  of  the  temperacreated  F i g u r e 19. Temperature, s a l i n i t y , and d i s s o l v e d oxygen d i s t r i b u t i o n s i n S e c h e l t I n l e t July 1961 •  during  27 between the up i n l e t flow of t i d e water and the compensating middepth down i n l e t flow. page 7 ,  This process was discussed more f u l l y on  The oxygen content of the water i n the deep layer  (layer I I I ) i s less than 1.0 m l / l .  This i s considered low and  a t t r i b u t e d to stagnant conditions.  The water i n t h i s l a y e r i s below  the layer of t i d a l i n f l u e n c e and i s e f f e c t i v e l y cut o f f from advection of highly oxygenated water.  Oxidation of organic matter  i n t h i s i s o l a t e d zone w i l l continue to reduce the oxygen concent r a t i o n u n t i l the water i s replaced by f l u s h i n g .  The temperature  and s a l i n i t y of the water i n layer I I I i s not uniform, but displays s l i g h t changes i n gradient between 65 and 125 metres.  This  "structure" i s thought to be a remnant l e f t by incomplete f l u s h i n g i n the previous winters.  See pages 8 and  9•  November 1961 I t has been assumed (page 5) that the density of the flood t i d e water increases with time i n the autumn.  As a r e s u l t , the t i d e  water sinks to intermediate l e v e l s and produces the current pattern proposed on page 9 . The p r o f i l e s f o r November 1961 i n d i c a t e some of the symptoms of t h i s motion.  (figure 20)  The flood t i d e water,  characterized ay low temperature and high oxygen concentration, has sunk to an intermediate l e v e l upon entering the i n l e t .  This water  has subsequently moved up i n l e t , pushing before i t the indigenous low-temperature, low-oxygen water, which r i s e s near the head of Salmon I n l e t .  The arrows drawn on the l o n g i t u d i n a l temperature  p r o f i l e (figure 20) represent t h i s flow.  The e f f e c t of t h i s move-  ment i s to produce a water mass of high oxygen concentration and low temperature near the mouth, and a mass of low-temperature, low-oxygen  F i g u r e 21. Temperature, s a l i n i t y March 1962.  and d i s s o l v e d  oxygen d i s t r i b u t i o n i n S e c h e l t I n l e t d u r i n g  28 water near the head.  The 10 °C isotherm defines, i n the body of  the i n l e t , the water least affected by t h i s movement. March I962 The l o n g i t u d i n a l oxygen p r o f i l e shown i n f i g u r e 21 indicates that f l u s h i n g of the deep water i s i n progress.  The oxygen concen-  t r a t i o n i n the deep layer has increased by 3»5 m l / l since November I96I.  This increase could only be produced by advection i n t o the  region of highly oxygenated flood t i d e water.  The water replaced  by t h i s inflow has been pushed up and towards the head of the i n l e t to form an oxygen minimum layer centred at 50 metres. May  1962  The average v e r t i c a l p r o f i l e s f o r March and May are compared i n f i g u r e 22.  The 0.3$« increase of s a l i n i t y i n the deep water i s  due to continued f l u s h i n g a f t e r the March c r u i s e .  This prolonged  f l u s h i n g has caused most of the water which formed the oxygen minimum i n March to leave the i n l e t . s l i g h t minimum at 50 metres.  However, there s t i l l e x i s t s a  The oxygen content i n the deep layer  has decreased by about 0.3 m l / l since March, i n d i c a t i n g that the f l u s h i n g of t h i s region has ceased.  When the deep f l u s h i n g stops,  the influence of the f l o o d t i d e i s l i m i t e d to the surface layers again, and the oxygen concentration i n the deep l a y e r decreases due to the oxygen demand of d e t r i t a l  material.  J u l y 1962 The p r o f i l e s f o r J u l y I962 ( f i g u r e 23) are s i m i l a r to p r o f i l e s f o r July I 9 6 I ( f i g u r e 19)  except that the oxygen concen-  t r a t i o n i n the deep zone i s about 3 m l / l higher i n July 1962.  The  data f o r March and May 1962 indicated f l u s h i n g of the deep water  F i g u r e 23. Temperature, J u l y 1962-  salinity  and d i s s o l v e d  oxygen d i s t r i b u t i o n i n S e c h e l t I n l e t d u r i n  F i g u r e 24. Temperature, s a l i n i t y October 1962.  and d i s s o l v e d  oxygen d i s t r i b u t i o n i n S e c h e l t I n l e t d u r i n g  29 during the winter of 1961-62.  The high oxygen values i n the deep  l a y e r i n July 1962 are i n d i c a t i v e of t h i s recent f l u s h i n g .  The low  oxygen values i n the deep layer i n J u l y 1961 i n d i c a t e that f l u s h i n g has not occurred f o r a considerable time p r i o r to t h i s c r u i s e . October I962 As observed previously the i n c r e a s i n g density of the flood t i d e water i n the autumn months i s accompanied by a loss of heat, and gain of s a l t i n layer I I . the t i d a l j e t (layer II) with the deep zone.  At t h i s time the l a y e r influenced by  becomes t h i c k e r due to increased exchange  These changes are observed i n the October  p r o f i l e s (figure 24) when compared to the July p r o f i l e s (figure 23). Notice also the oxygen minimum, just under layer I I ,  which was  formed during the f l u s h i n g i n the winter of 1961-62. November 1962 The November 1962 data presents "the exception to the r u l e " . Comparison of the average v e r t i c a l p r o f i l e s f o r October and November (figure 25) shows a decrease i n s a l i n i t y i n l a y e r  II  instead of an increase which would be expected i f the f l o o d t i d e density was i n c r e a s i n g .  The v e r t i c a l temperature p r o f i l e s f o r  stations near the head, middle, and mouth of the i n l e t are given i n f i g u r e 27.  These p r o f i l e s emphasize the temperature decrease  accompanying the s a l i n i t y decrease.  The p r o f i l e s f o r the middle and  head show a temnerature maximum at 40 metres.  The l a y e r above this  maximum has cooled, considerably due to the r e l a t i v e l y cool t i d e water moving up i n l e t near the surface and mixing with the underlying water.  The cooling of the upper 40 metres i s most l i k e l y not due to  wind mixing. The temperature and s a l i n i t y i n a wind mixed layer i s  F i g u r e 25• Temperature, s a l i n i t y November 1962 •  and d i s s o l v e d  oxygen d i s t r i b u t i o n i n S e c h e l t I n l e t d u r i n g  30 more uniform than observed here.  The body of water near the  mouth, which i s nearly homogeneous with respect to temperature i s a product of the t i d a l j e t .  Figure 27 • V e r t i c a l temperature p r o f i l e s near the head, middle and mouth of the Sechelt-Salmon I n l e t system during November 18th 1962. January I963 The January p r o f i l e s shown i n figure 26 exhibit the most convincing data i n favour of a mid-depth i n t r u s i o n of f l o o d water which subsequently moves up i n l e t .  The l o n g i t u d i n a l  tide profiles  of temperature, and oxygen show a very pronounced tongue of homogeneous low-temperature high-oxygen water near the mouth.  This  homogeneous water, which i s the end r e s u l t of the t i d a l j e t , i s flowing up i n l e t .  Because of i t s density, most of t h i s layer  lies  below the threshold depth of the s i l l , and the ebb t i d e w i l l be composed of the water above.  V e r t i c a l p r o f i l e s at the head and  mouth, of temperature and oxygen, are shown (figure 28) to emphasize the homogeneity of the t i d a l water and the up i n l e t flow.  The two  low-temperature "bumps" A and B i n the temperature p r o f i l e correspond  F i g u r e 29. Temperature, s a l i n i t y February 1963.  and d i s s o l v e d  oxygen d i s t r i b u t i o n i n S e c h e l t  Inlet during  31  Figure 28. Temperature and oxygen p r o f i l e s near the head and mouth of the Sechelt-Salmon I n l e t system during January 20th,  1963.  exactly with the high oxygen ""bumps" A' and B  1  i n the oxygen p r o f i l e .  The water i n the layer defined "by these "bumps" has moved up i n l e t i n t h i n "sheets". Each sheet i s probably produced by a d i f f e r e n t t i d e , and exhibits s l i g h t l y d i f f e r e n t density. February I963 The February p r o f i l e s (figure 29) show the same processes that were dominant i n January, but not so s p e c t a c u l a r l y .  The  l o n g i t u d i n a l plots of temperature and oxygen show tongues of lowtemperature high-oxygen water i n t r u d i n g up i n l e t at about 50 to 75 metres. March I963 The March p r o f i l e s (figure 3 0 ) display very l i t t l e that was not evident i n the January and February d i s t r i b u t i o n s .  Mid-depth  i n t r u s i o n s are evident i n the temperature and oxygen p r o f i l e s . The  Figure 31. Temperature, s a l i n i t y and dissolved i n Sechelt I n l e t during July 1957.  oxygen d i s t r i b u t i o n  32  s a l i n i t y and thus density of the water i n l a y e r I I i s greater i n March as shown i n the comparison between the two months. J u l y 1957 The f i r s t c r u i s e to the Sechelt - Salmon Inlet system was i n J u l y 1957«  The data (figure 31) are given out of chronological  order because they were taken four years before the series.  continuous  Notice how s i m i l a r the p r o f i l e s f o r J u l y 1957 (figure 3l)  are to the p r o f i l e s f o r J u l y 1962 ( f i g u r e 23).  Because of t h i s  s i m i l a r i t y i t i s assumed that the previous h i s t o r y of each d i s t r i b u t i o n i s the same.  Layer I i s due to runoff and layer I I i s  the region influenoed by the t i d a l j e t . The water i n l a y e r I I I i s nearly uniform with respect to temperature and s a l i n i t y , while the oxygen content of t h i s deep zone i s r e l a t i v e l y high.  This high  oxygen i s a t t r i b u t e d to recent f l u s h i n g , most l i k e l y i n the winter of 1956-57.  The oxygen minimum at 100 metres was reported by  Pickard (1961).  I t i s believed to be a remnant of the o l d low-  oxygen deep water that was l i f t e d up by a recent i n t r u s i o n of water that flushed the deep zone.  53 Narrows I n l e t Narrows I n l e t (figure 18) i s p a r t i a l l y separated from Sechelt I n l e t by a shallow s i l l at Tzoomie Narrows. miles long and \ mile wide.  The I n l e t i s about 5ir  The greatest depth i n the i n l e t i s  only about 85 metres, and therefore i t i s the shallowest i n l e t i n the J e r v i s I n l e t system.  The annual v a r i a t i o n s i n the temperature,  s a l i n i t y , and oxygen d i s t r i b u t i o n s are very s i m i l a r to those i n Princess Louisa and Sechelt I n l e t s .  I t i s thought that the current  patterns proposed previously are v a l i d i n Narrows  Inlet.  The v e r t i c a l temperature, s a l i n i t y , and oxygen p r o f i l e s divide the water column i n t o three d i s t i n c t l a y e r s .  The runoff  layer of r e l a t i v e l y low s a l i n i t y water occupies the top 5 to 10 metres.  Below the surface l a y e r i s the region a f f e c t e d by the  t i d a l j e t . The thickness of t h i s intermediate l a y e r i s u s u a l l y about 50 metres.  The water i n the i n l e t below the influence of the  t i d a l j e t occupies the t h i r d l a y e r .  This i s the deep l a y e r ,  u s u a l l y characterized by a uniform temperature and s a l i n i t y . Because the i n l e t i s so shallow the deep l a y e r i s t h i n and sometimes i s hard to detect.  The v e r t i c a l temperature s a l i n i t y , and dissolved  oxygen p r o f i l e s f o r the only s t a t i o n i n the i n l e t are shown i n f i g u r e 3 2 f o r ten cruises between J u l y 1961 and March 1963*  These  p r o f i l e s are discussed below. J u l y 1961 The surface (layer I ) , intermediate (layer I I ) , and deep (layer I I I ) layers are evident i n the temperature and s a l i n i t y d i s t r i b u t i o n s f o r J u l y 1961.  The almost l i n e a r s a l i n i t y and  temperature gradients i n l a y e r I I are a t t r i b u t e d to the.shear  I00  10  J  23  12  July  1961  25  2 7  2  6  4  6  7 November  100 8  25  10 _L_  27  L__  0i  1961  I  Metres IOO J  March  23  1 0 0 *•  1962  27  25  2  _l_  May  Temperature  °C.  J  July  -4.  1962  0  I00  8  4  JL.  2  _l_  4 _1_  6 —i—  1962  Salinity  %o  Oxygen  F i g u r e 32. V e r t i c a l p r o f i l e s of temperature, s a l i n i t y , oxygen i n Narrows I n l e t .  ml./1.  and d i s s o l v e d  34 between the up i n l e t flow of tide water and the down i n l e t flow of deeper water.  The deep layer was r e l a t i v e l y stagnant r e s u l t i n g i n  a low oxygen concentration.  The s l i g h t oxygen maximum at 50 metres,  i f r e a l , may be due to the t i d e water flowing up i n l e t at middepths . November 1961 Layers I and I I were present i n November I96I but the data does not extend to the bottom of the i n l e t and layer I I I i s not apparent.  The water i n l a y e r I I was more uniform with respect to  temperature, s a l i n i t y , and oxygen than i n J u l y  I96I.  Also, the  density of the water i n t h i s layer was greater i n November.  These  changes are i n d i c a t i v e of an increasing tide water density. Instead of flowing u p - i n l e t near the top of l a y e r I I , the t i d e water seeks an intermediate l e v e l , thereby d i s p l a c i n g upward the upper water i n layer I I . March I962 The data taken i n March 1962 extends to the bottom of the inlet.  The density of the water i n layer I I was greater than  previously, and the oxygen content of the deep water was much higher.  I t i s believed that the t i d e water sank r i g h t to the  bottom of the i n l e t and flushed out the o l d low oxygen water. May  1962  The p r o f i l e s f o r May 1962 are very s i m i l a r to those of March but the s a l i n i t y i n layer I I was greater.  This increase i s  i n d i c a t i v e of continued f l u s h i n g of the deep water a f t e r the March cruise.  The oxygen content of the deep water i s lower because of  oxygen demand.  8  10  12  23  25  27  0  2  4  2  4  I 00*  February  8  10  23  29  March  Temperature °C. Figure  1963  27  0  J  I  1963  Salinity  %o  Oxygen  3 2 . (continued) V e r t i c a l p r o f i l e s of temperature, d i s s o l v e d oxygen i n Narrows I n l e t .  L  35 July  1962 The p r o f i l e s f o r J u l y 1962 are very s i m i l a r to those f o r  July 1961.  The water i n layer I I I was  the f l u s h i n g i n the winter of I 9 6 I - 6 2 . lower part of the deep l a y e r was about 3*5 m l / l since March.  denser i n 1962 because of The oxygen content i n the  nearly zero which was a drop of  This large oxygen demand may be due  to a reducing environment on the bottom; a r e s u l t of undecomposed d e t r i t u s f a l l i n g from the surface l a y e r s . October 1962 The v e r t i c a l p r o f i l e s f o r October 1962 indicate that the density of the t i d e water was  increasing with time.  seeks an intermediate l e v e l a f t e r entering the i n l e t .  This water This  resulted i n h i g h l y oxygenated water i n t r u d i n g between 30 and 50 metres.  This i n t r u s i o n i s evident i n the oxygen maximum at 30  metres. November 1962 The November 1962 p r o f i l e s are s i m i l a r to the October p r o f i l e s except the c h a r a c t e r i s t i c s of the water i n layer I I changed s l i g h t l y .  This change was due to a change i n the  c h a r a c t e r i s t i c s of the t i d e water entering the i n l e t . January 1963 During the cruise i n January 1963 most of the i n l e t was blocked by t h i n i c e .  I t was  impossible to occupy the usual s t a t i o n  and the data obtained does not extend i n t o the deep zone.  By  extrapolation between the November 1962 and February 1963 data the dotted l i n e s are drawn on the January 1963 p r o f i l e s to represent the deep water c h a r a c t e r i s t i c s .  The p r o f i l e s show that the density  36 of the water i n layer I I has decreased since November, while the oxygen content has increased. Because the water i n layer I I i s strongly influenced by the t i d e water, these changes are due to v a r i a t i o n s i n the t i d e water c h a r a c t e r i s t i c s . February 1963 and March 1963 The v e r t i c a l p r o f i l e s f o r February and March 1963 are very s i m i l a r and show l i t t l e change since January 1963. The oxygen minimum centred at 10 metres i n January, February, and March i s thought to be due to the upward displacement of low oxygen water by the intermediate i n t r u s i o n of t i d e water.  37 I I I DEEP SILLED INLETS  Jervis Inlet The general features of J e r v i s I n l e t have been described i n the Introduction.  Because of the deep s i l l i n the i n l e t i t i s  assumed that the general c i r c u l a t i o n pattern i s estuarine i n character.  Thus the t i d a l flow does not noticeably a f f e c t the  v e r t i c a l density s t r a t i f i c a t i o n i n the i n l e t .  In the f o l l o w i n g  d e s c r i p t i o n of the data emphasis i s placed on the difference i n the temperature, s a l i n i t y , and dissolved oxygen d i s t r i b u t i o n s between two c r u i s e s .  I t i s assumed that, i f two points A and  B ( ay) are characterized by d i f f e r e n t p r o p e r t i e s , a flow from A s  to B between two cruises w i l l be revealed by f i n d i n g the properties of A at B on the l a t e r c r u i s e .  In t h i s way a rough idea of the net  c i r c u l a t i o n between two cruises can be found. I t i s concluded that an estuarine c i r c u l a t i o n i s not always the dominant c i r c u l a t i o n pattern i n the i n l e t .  An estuarine c i r c u l a t i o n i s caused and  c o n t r o l l e d by the amount of surface runoff.  Because the surface  runoff i n J e r v i s I n l e t i s r e l a t i v e l y small, other f a c t o r s , such as changes i n the meteorological and oceanographic conditions i n the area, w i l l produce flows that dominate the estuarine c i r c u l a t i o n . March 1962 The average v e r t i c a l p r o f i l e s of temperature and s a l i n i t y f o r March 1962 are shown i n f i g u r e 33•  The l o n g i t u d i n a l p r o f i l e  of oxygen content ( f i g u r e 33a) i s given to emphasize the oxygen minimum s i t u a t e d at mid-depth near the head of the basin.  Figure 34a. Longitudinal section of dissolved oxygen i n J e r v i s I n l e t during May 1962.  38  •2002  400-  Temperature  °c  I  Salinity  %•  Figure 33* Average v e r t i c a l p r o f i l e s of temperature and s a l i n i t y f o r J e r v i s I n l e t during March 196"2. The surface l a y e r (layer I) i s defined by r e l a t i v e l y low temperature and low s a l i n i t y .  The water below 150 metres ( l a y e r I I I )  i s nearly homogeneous with respect to temperature and s a l i n i t y . The t r a n s i t i o n i n water properties between the surface layer and the deep homogeneous l a y e r i s gradual, and the depth assigned to the surface l a y e r i s somewhat a r b i t r a r y .  Loss of heat from the surface  water by r a d i a t i o n , and d i l u t i o n by runoff water are the causes of the low temperature and low s a l i n i t y of the surface and intermediate layers.  I t i s d i f f i c u l t to understand why the depth of this  influence i s so great.  For example, the surface l a y e r i n Princess  Louisa and Sechelt I n l e t s never becomes greater than 15 to 20 metres, while i n J e r v i s i t i s 30 to 50 metres (figure 33) with noticeable influence up to 150 metres.  This problem i s discussed  further on page 46. The oxygen minimum centred at 200 metres at the head of the basin i s defined by the water containing less than 2 m l / l of oxygen. This minimum l a y e r i s a c h a r a c t e r i s t i c feature of t h i s i n l e t , having been observed during every v i s i t .  Station  3  6  9  Figure 34« V e r t i c a l p r o f i l e s of temperature, s a l i n i t y , and dissolved oxygen at three positions i n Jervis I n l e t during March and May 1962.  39 May 1962 V e r t i c a l p r o f i l e s f o r March and May of temperature, s a l i n i t y , and oxygen are compared i n f i g u r e 34» f o r three s t a t i o n s i n the inlet.  Because of lack of space and the p o s s i b i l i t y of confusion i t  i s not p r a c t i c a l to present p r o f i l e s f o r a l l the s t a t i o n s . Stations Je. 3» 6, and 9 are given to represent conditions near the mouth, middle, and head of the i n l e t r e s p e c t i v e l y . The top 5 to 10 metres of the water column i n May e x h i b i t properties i n d i c a t i v e of s p r i n g .  The temperature i s much higher  than i n March and the s a l i n i t y much lower, i n d i c a t i n g increased s o l a r r a d i a t i o n and runoff. i s also higher i n May. phytoplankton  The oxygen content of the top 10 metres  This could be due to oxygen production by  or associated with the runoff water.  The l a y e r of water BC (figure 34) e x h i b i t s a marked decrease i n temperature coupled with an increase i n oxygen content between March and May.  The only water i n the i n l e t i n March with such a  temperature and oxygen content i s i n the surface l a y e r . Because of the s t a b i l i t y i t i s impossible f o r the surface water to descend to the l a y e r BC.  I t i s therefore assumed that t h i s change i s due to  an inflow of water from Malaspina S t r a i t .  I t , i s d i f f i c u l t to say  how f a r up the i n l e t t h i s "new" water has progressed f o r any h o r i z o n t a l flow w i l l push indigenous water ahead of i t .  Station 9  e x h i b i t s s l i g h t changes i n l a y e r BC but t h i s i s probably due to replacement by water already i n the i n l e t i n March.  The layer  between the i n f l o w i n g water and the surface layer ( l a y e r AB f i g u r e 34) i s occupied i n May by water displaced upward by the mid-depth i n t r u s i o n .  Because of the nature of the gradients before  Figure 3 5 . V e r t i c a l p r o f i l e s of temperature, s a l i n i t y , and dissolved oxygen at three positions i n J e r v i s I n l e t during May and July 1 9 6 2 .  40 the i n t r u s i o n , layer A B reveals a l o s s of oxygen, a gain i n temperature and a gain i n s a l i n i t y .  The temperature minimum evident  at 10 metres at s t a t i o n s 6 and 9 i s a remnant of the bottom of the previous surface l a y e r .  In March the bottom of the surface l a y e r  rested at about 60 metres (figure 34)» but the mid-depth inflow has pushed i t up to about 20 metres.  The surface layer i n May defined  by high temperature and low s a l i n i t y i s above 20 metres. Near the mouth ( s t a t i o n 3 f i g u r e 34) "the l a y e r which e x h i b i t s the temperature minimum i s not present.  E i t h e r i t has been eroded by exchange with  the surface l a y e r or the subsurface inflow has pushed i t up i n t o the surface layer to be c a r r i e d out. The l o n g i t u d i n a l oxygen p r o f i l e f o r May (figure 34a) when compared with the same p r o f i l e f o r March (figure 33a) reveals a change i n the p o s i t i o n of the oxygen minimum.  I t appears that the  mid-depth inflow of high oxygen water, i n d i c a t e d by the arrows has cut the minimum i n t o two p a r t s .  The upper part has been pushed up  near the surface, while the lower h a l f remains much the same. In t h i s way some of the water with oxygen content less than 2 m l / l j o i n s the surface outflow, and leaves the i n l e t .  The amount of  inflow however, i s not great enough to remove a l l of the oxygen minimum. J u l y 1962 The v e r t i c a l p r o f i l e s f o r May and July are compared i n f i g u r e 35. The surface layer has become warmer due to increased s o l a r r a d i a t i o n , and less s a l i n e due to increased runoff.  Below  the surface layer the three regions A B , B C , and C D are defined (figure 35). The regions A B and C D e x h i b i t gains i n oxygen content  Figure 35a. Longitudinal section of dissolved oxygen i n J e r v i s I n l e t during July 1962. 10 No. Mi.  Figure 36a. Longitudinal section of dissolved oxygen i n J e r v i s I n l e t during October 1962.  41  since May while region BC shows a l o s s .  The layers showing a gain  in oxygen content are also associated with a loss i n temperature, but the middle layer exhibits a slight gain i n temperature.  It i s  suggested that changes i n the top and bottom layers (AB and CD) represent flows into the i n l e t , while the changes i n the middle layer are a result of an outflow.  Thus between May and July there  has been an inflow at about 300 metres and at 50 metres.  An  outflow has taken plaoe i n a layer centred at 125 metres. drop i n salt content of about 0.2 to  0.5$o  The  i n layer AB is due to  the inflow just under the surface layer. The oxygen d i s t r i b u t i o n shown i n figure 35a has changed as a result of these flows.  The flow labelled I i n the figure is  the  deep inflow, which has increased the oxygen content near the mouth at 300 metres. 125 metres.  Arrow II represents the flow out of the i n l e t at  This flow has taken the oxygen minimum with i t .  Flow  III is the influx centred at 50 metres, which has forced the oxygen minimum to greater depths.  Flows I and III seem to "squeeze" the  intermediate layer out of the i n l e t . October 1962 Between July and October 1962 there has been an inflow of water into region CD (figure 36).  This "new" water is colder by  0.3 to 0.4 C° , while the oxygen content is greater by 0.8 to 1.0 m l / l than the water which was replaced.  The water which has been  replaced by the deep inflow has moved up into region BC (figure 36a).  This is why the oxygen content i n the region BC is lower,  and the temperature and s a l i n i t y are higher i n October. difficult  It  is  to determine whether the inflow of water into region CD  Station  27  6  3  29  31  27  9  29  Salinity  31  2 7 2 9  31  %,  Figure 36. V e r t i c a l p r o f i l e s of temperature, s a l i n i t y , and dissolved oxygen at three positions i n J e r v i s I n l e t during July and October 1962.  42 has just balanced the outflow i n the surface l a y e r .  I f there has  been an increased outflow i n the surface l a y e r or at some i n t e r mediate depth i t i s not obvious. The surface layer i n October has changed only s l i g h t l y since July.  I t i s a l i t t l e t h i c k e r due to continued exchange with the  water below the surface l a y e r .  The temperature of the top 5 metres  i s l e s s , i n d i c a t i n g a net loss of heat by r a d i a t i o n from the surface.  Higher s a l i n i t i e s i n the top 5 metres i n d i c a t e a decrease  i n runoff. The arrows on the l o n g i t u d i n a l oxygen p r o f i l e represent the net currents between J u l y and October.  (figure 36a) The arrows  l a b e l l e d I represent the inflow of highly oxygenated water that has entered the deep zone below s i l l depth.  Arrow I I i s the upward  movement of water r e s u l t i n g from the deep inflow.  This upward  displacement has brought with i t water of oxygen content less than was previously there.  The oxygen minimum near the head of the  i n l e t i s higher i n October due to the upward push from the deep influx.  The volume of water containing less than 2 m l / l of oxygen  i s greater i n October than i n J u l y .  This decrease of oxygen content  i s a t t r i b u t e d to increased oxygen demand i n the i n l e t during the summer, and not to advection of low oxygen water from outside the inlet.  The arrow l a b e l l e d I I I represents a questionable flow.  The 2.5 m l / l oxygen i s o p l e t h i s found much further down i n l e t than in July.  This i s e i t h e r due to the upward flow of the deep water  or to a down i n l e t flow centred at about 175 metres. possible that both flows are present.  It is  400 Temperature  *C  Figure 37. V e r t i c a l p r o f i l e s of temperature, s a l i n i t y , and dissolved oxygen at three positions i n J e r v i s I n l e t during October and November 1962.  43  November 1962 V e r t i c a l p r o f i l e s f o r October and November are compared i n f i g u r e 37«  The high-oxygen low-temperature water that entered the  deep zone between J u l y and October i s evident nearer the head i n November ( s t a t i o n 9 f i g u r e 37).  This movement has brought water of  higher oxygen content to the deeper layers i n the upper h a l f of the basin.  This has tended to accentuate the oxygen minimum centred at  150 metres near the head.  Another noticeable difference between  October and November i s that the whole water column above 150 metres seems to have been displaced downward about 20 metres. example, notice how s i m i l a r the p r o f i l e sections marked A ' B to the sections marked AB i n f i g u r e 37«  1  For are  The s e c t i o n AB represents  the s t r u c t u r e i n October while A ' B ' i s that i n November.  It is  suggested that there has been a mid-depth out flow centred at about 200 metres.  This l o s s of water has caused the water above i t to  descend and the surface layer to thicken i n order to compensate f o r the net loss of water from the i n l e t .  The r e l a t i o n between the  mid-depth outflow and the thickness of the surface layer i s discussed f u r t h e r on page 46. The change i n the surface l a y e r between October and November i s shown best by the temperature p r o f i l e s at s t a t i o n 6 (figure 37) • The layer AB i n October has been lowered to the layer A ' B ' by the loss of water at mid-depth.  The top 5 to 10 metres has cooled due  to increased l o s s of heat by r a d i a t i o n .  This top region i s  considered the surface l a y e r f o r i t i s the only water d i r e c t l y affected by the changes i n s o l a r heating and runoff. AB has descended to A'B  1  I f the layer  due to exchange there would be no  Stations  Figure 37a. Longitudinal section of dissolved oxygen i n Jervis Inlet during November 1962. 10 N a . Mi.  Figure 38a. Longitudinal section of dissolved oxygen i n Jervis Inlet during January 1963 •  St  6  ation 7  9  9 11  7  9  11  27  29  31  a» Q  4 001 Temperature  27  29  2  j  27  31  4  J  29  31  °C  6  u  Figure 38. V e r t i c a l p r o f i l e s of temperature, s a l i n i t y , and dissolved oxygen at three p o s i t i o n s i n J e r v i s I n l e t during November 1962 and January 1963-  44  temperature maximum at 15 metres. Arrow I shown on the l o n g i t u d i n a l oxygen p r o f i l e ( f i g u r e 3 7 a ) represents  the t a i l  end of the inflow of h i g h l y oxygenated water  "between J u l y and October.  Plow I I represents  the mid-depth outflow  which has caused the water above 200 metres to be d i s p l a c e d down (arrow  III).  January 1963 The changes i n the v e r t i c a l p r o f i l e s between November and January are very s i m i l a r to the changes noted between October and November.  N o t i c e i n f i g u r e 38 how the l a y e r l a b e l l e d AB seems to  have descended to A . ' B ' . water column i s  This downward displacement of part of  the  again caused by an outflow at i n t e r m e d i a t e depths,  with a compensating i n f l o w i n t o the s u r f a c e l a y e r . l a y e r could be defined as the top 50 metres,  The s u r f a c e  which seems too t h i c k  f o r any o r d i n a r y s u r f a c e mixing p r o c e s s . The l o n g i t u d i n a l oxygen p r o f i l e ( f i g u r e 3 8 a ) shows the i n c r e a s e i n depth by 50 metres  of the core of the oxygen minimum  between November 1962 and January 1 9 6 3 •  The i n c r e a s e i n oxygen  content i n the water above the oxygen minimum i s proposed mid-depth outflow i s  also  evident.  not too evident i n t h i s p l o t ,  f o r the  2 m l / l oxygen i s o p l e t h has r e t r e a t e d up i n l e t s i n c e November. is  The  It  supposed that the decrease i n the volume of water c o n t a i n i n g l e s s  than 2 m l / l of oxygen i s due to mixing with more h i g h l y oxygenated waters.  The decrease i n oxygen content i n the deep water below  depth ( f i g u r e 3 8 a ) i s m a t e r i a l i n the water.  a t t r i b u t e d to the oxygen demand of organic  sill  Figure 39. V e r t i c a l p r o f i l e s of temperature, s a l i n i t y , and dissolved oxygen at three positions i n J e r v i s I n l e t during January and February 1963*  Morch  Figure 40. V e r t i c a l p r o f i l e s of temperature, s a l i n i t y , and dissolved oxygen at three positions i n J e r v i s I n l e t during February and March I963.  45 February 1963 Comparison of the January and February p r o f i l e s (figure 39) reveals that a mid-depth inflow has taken place. This inflow has displaced upward the water above i t and thus produced a thinner surface l a y e r .  Region AB (figure 39) i n January has l i f t e d up to  become layer A'B' i n February.  To compensate f o r the i n f l o w ,  greater outflow of surface water has taken place. This has produced a thinner surface l a y e r i n February.  The depth of the  sub-surface i n t r u s i o n i s about 150 to 200 metres.  This i s most  e a s i l y recognized by inspection of the v e r t i c a l and l o n g i t u d i n a l p r o f i l e s of oxygen content (figure 39a)•  The i n t r u s i o n i s  characterized by an increase i n oxygen content between 150-200 metres, e s p e c i a l l y noticeable i n the tongue of high oxygen water at 150 metres at stations 6 and 7 on the l o n g i t u d i n a l p r o f i l e . March 1963 The changes i n temperature, s a l i n i t y and oxygen between February and March 1963  a r e  v e i  between November and January.  T s i m i l a r to the changes noted The layer l a b e l l e d AB i n the February  p r o f i l e s (figure 40) has been displaced down to become layer A'B' i n March.  The surface layer consequently i s t h i c k e r i n March.  The  mid-depth outflow that caused the upper layers to descend occurred at 150 metres.  This i s evident by the oxygen decrease at this  l e v e l (figure 40). The l o n g i t u d i n a l oxygen p r o f i l e f o r March (figure 40a) shows the oxygen minimum near the head of the i n l e t i n much the same p o s i t i o n as i t was i n February (figure 39a).  The values of oxygen  content i n the upper 150 metres are generally higher than i n  Stations  Figure 39a. Longitudinal section of dissolved oxygen i n J e r v i s I n l e t during February 1963• .10 No.  Figure 40a. Longitudinal section of dissolved oxygen i n J e r v i s I n l e t during March I963.  Mi.  46 February, due to the raid-depth outflow. The Surface Layer and Mid-depth Flows In t h i s account i t has been stated that a mid-depth outflow r e s u l t s i n an increase i n the thickness of the surface l a y e r , also a mid-depth inflow r e s u l t s i n a decrease i n the surface l a y e r thickness.  Although i t i s implied that the flow i s the cause of  the change i n thickness of the surface l a y e r , i t i s not n e c e s s a r i l y so.  This question of which phenomenon comes f i r s t i s u s u a l l y  referred to as the "chicken and egg" problem. The s a l i n i t y at 50 and 100 metres i s p l o t t e d against time i n f i g u r e 41• A rough estimate of the surface layer thickness i s also shown. There i s a strong negative c o r r e l a t i o n , from November 1962 to March 1963, between the s a l i n i t y curve and thickness of the surface l a y e r . When the s a l i n i t y decreased i n January and March the surface layer became t h i c k e r . The opposite i s true i n November and  February. THICKNESS  OF  THE  50  (A Ul  31.01  2 5 « ut  30.5  z Z  to  a  SALINITY  4 V>  AT  100  METRES  50  METRES  30.0-  29.5-  SALINITY  AT  29.01 *  1—1—1—1—1 J  A  1 0  1  1—1 0  1 F  1 1 '  TIME  A  Figure 41. S a l i n i t y at 50 and 100 metres at s t a t i o n Je. 3, and the thickness of the surface l a y e r p l o t t e d against time.  47 It has been observed, Pickard and Rodgers 1959, that "in the presence of' an up-inlet wind" there is a flow, "up-inlet i n the top 5-10 metres".  The measurements which this statement refer  to were taken i n Knight I n l e t , but i t is assumed that the same phenomenon would occur i n Jervis I n l e t . It is proposed that an up-inlet wind blowing for a prolonged period of time w i l l stop, and possibly reverse, the normal down i n l e t flow of runoff wateri and raise the water l e v e l .  This would thicken the surface layer, To re-establish the water l e v e l a  movement of water out of the i n l e t , at mid-depths, takes place. As this water leaves the i n l e t , the water above the outflow is displaced downward.  Because the s a l i n i t y increases with depth and  oxygen content generally decreases,  each level between the surface  layer and the outflow experiences a drop i n s a l i n i t y and an increase i n oxygen content.  The changes i n temperature are not so regular.  The mid-depth outflow w i l l oreate, at i t s own l e v e l , a horizontal pressure gradient which tends to reverse the direction of the flow. reverses  This pressure gradient builds up u n t i l the flow  to create a mid-depth up-inlet flow.  Then the water i n  the i n l e t above the flow i s displaced upward, and to compensate for the gain i n water volume the surface layer flows out of the i n l e t faster,  thus decreasing i t s thickness.  Thus an increase i n s a l i n i t y  at mid-depth (50 to 100 metres) is associated with a non-estuarine sub-surface inflow, and a decrease i n the thickness of the surface layer.  Also a decrease i n s a l i n i t y at intermediate depths can be  correlated with a mid-depth outflow and an increase i n the of the surface layer.  thickness  48  The o s c i l l a t i o n s (figure 41) appear to be greater i n the winter of 1962-63.  The winds that s t a r t the process may be the  strong winds u s u a l l y associated with the autumn months i n southern B r i t i s h Columbia.  I t was observed on October 20, 1962 that the  water l e v e l at Pender Harbour was e x t r a o r d i n a r i l y high.  This i s  a t t r i b u t e d to the strong winds associated with Typhoon Frieda which entered the area at that time.  This phenomenon may have been  the cause of the v a r i a t i o n s i n the thickness of the surface l a y e r shown i n f i g u r e 41» which i n turn r e s u l t e d i n the o s c i l l a t o r y middepth flows.  I t would be i n t e r e s t i n g to take a s e r i e s of oceano-  graphic and meteorological observations i n the S t r a i t of Georgia and J e r v i s I n l e t during a prolonged period of strong southerly winds.  The data would be c o l l e c t e d i n the hope of c o r r e l a t i n g the  wind vector, the depth of the surface l a y e r , and the oceanographic conditions i n the deep water.  I t i s predicted that the depth of  the surface layer w i l l increase i n the d i r e c t i o n of the wind vector. The s a l i n i t y w i l l decrease i n t h i s d i r e c t i o n , and at some mid-depth there w i l l be a flow of water i n the opposite d i r e c t i o n . Oxygen Minima The changes i n p o s i t i o n and volume of the water i n J e r v i s I n l e t containing less than 2 m l / l of oxygen have been described. During the period of t h i s study t h i s mass of water formed an oxygen minimum at intermediate depths near the head of J e r v i s I n l e t .  The  net flows suggested by the v a r i a t i o n s i n p o s i t i o n of t h i s minimum have confirmed some of the suggestions made by Pickard ( I 9 6 I ) .  He  proposed that "small but frequent inflows of oxygenated s a l i n e water from outside may  take place over the entrance s i l l and  spread  49 over the i n l e t bottom, so that the oxygen-deficient water i s held at mid-depth".  These flows occurred between March and May 1962  (page 40), May and J u l y 1962 (page 41) and J u l y and October 1962 (page 42).  Although the l a s t of these flows was the only one that  sank to the bottom, a l l the mid-depth u p - i n l e t flows tended to decrease the depth of the oxygen-deficient water.  I t has been  suggested here (page 47) that mid-depth out flows also occur.  One  such flow took place between October and November 1962 (page 44)• I f such a flow occurs at the same depth as the core of the oxygen minimum, the minimum w i l l appear to flow down i n l e t .  I f the depth  of the down i n l e t flow i s greater than the depth of the oxygen minimum, the oxygen-deficient water w i l l be displaced downward. The fresh water runoff i n J e r v i s I n l e t i s r e l a t i v e l y small, and the induced estuarine c i r c u l a t i o n i s correspondingly weak. Because of the absence o f a large continual u p - i n l e t mid-depth flow, the  oxygen d e f i c i e n t water i s not replaced f a s t e r than i t i s formed  by oxygen demand i n the water.  A large runoff i n l e t such as Bute  does not possess an oxygen minimum as prominent as that found i n J e r v i s , (Tabata and Pickard, 1957; Pickard, 196l). In the shallow s i l l e d i n l e t s oxygen d e f i c i e n t waters were found either i n a mid-depth minimum or i n the deep l a y e r .  I t was  suggested (page 31 and 32) that low oxygen waters i n the deep zone are  the r e s u l t of stagnant conditions, and a mid-depth minimum i s  due to upward displacement of deep low-oxygen water by an i n t r u s i o n i n t o the deep layer of h i g h l y oxygenated water.  50  17  SUMMARY  The study of the v a r i a t i o n i n the d i s t r i b u t i o n of temperature, s a l i n i t y and dissolved oxygen during the period from July 1961 to March 1962 i n the J e r v i s I n l e t system has shown a marked difference i n the c i r c u l a t i o n patterns i n a shallow s i l l e d i n l e t and a deep silled inlet.  I t was proposed that a shallow s i l l forces the t i d e  water to enter an i n l e t i n a turbulent j e t which produces a mass of homogeneous water near the mouth. The depth of t h i s water i s greater than the s i l l depth due to the Coanda e f f e c t .  In general the t i d e  water i s of a d i f f e r e n t density than the indigenous water at the same depth and a h o r i z o n t a l pressure gradient r e s u l t i n g i n h o r i z o n t a l flows i s produced.  I f the t i d e water i s less dense than the  indigenous water the former w i l l tend to flow up i n l e t on top of the indigenous water which tends to flow down i n l e t .  I f the t i d e water i s  denser than the indigenous water the t i d e water flows up i n l e t at an intermediate depth d i s p l a c i n g upward the indigenous water. below the influcence of the t i d a l j e t i s r e l a t i v e l y  The water  stagnant and  displays a decreasing oxygen content. Flushing of the deep water occurs when the t i d e water i s denser than a l l the water i n the i n l e t . I t was observed that a deep i n t r u s i o n of t h i s kind displaced upward the oxygen d e f i c i e n t water i n the deep region, thereby producing an oxygen minimum at mid-depths.  Because of the t i d a l j e t , the  temperature and s a l i n i t y d i s t r i b u t i o n s i n the shallow s i l l e d i n l e t s , Princess Louisa, Sechelt, and Narrows are divided i n t o e s s e n t i a l l y three layers.  The surface layer d i l u t e d by runoff water extends to  f i v e or ten metres.  The intermediate layer which i s influenced by  51  the t i d a l j e t extends to varying depths depending on the density of the t i d e water, and the deep layer extends from the bottom of the intermediate layer to the bottom. The v e r t i c a l s t r u c t u r e of the water i n the deep s i l l e d i n l e t (Jervis) i s not influenced by the t i d a l flow.  I t was assumed that a  weak estuarine c i r c u l a t i o n existed i n J e r v i s due to the r e l a t i v e l y small fresh water runoff i n t o the i n l e t .  A mid-depth o s c i l l a t o r y  flow of unknown period during the winter of 1962-63 was described. I t was proposed that strong south-westerly winds i n the autumn, p a r t i c u l a r l y those associated with Typhoon F r i e d a , caused the water l e v e l i n J e r v i s to r i s e .  To compensate f o r the increase i n water  volume a mid-depth outflow was created.  This outflow produced a  h o r i z o n t a l pressure gradient that tended to reverse the d i r e c t i o n of the flow.  When the flow reversed, the water l e v e l i n the i n l e t again  became greater and the surface outflow increased.  A negative  c o r r e l a t i o n between the d i r e c t i o n of t h i s mid-depth flow and the depth of the surface l a y e r was noted. The low oxygen content i n the water at mid-depths near the head of J e r v i s I n l e t was a t t r i b u t e d to the weak estuarine c i r c u l a t i o n which r e s u l t s i n a slow renewal of the water near the head.  i 52  V  APPENDIX  Some Observations During May 1963 Observations were made i n the J e r v i s I n l e t system i n May 19&3, as part of the series o f c r u i s e s .  Because the cruise was taken at  the time t h i s thesis was i n preparation the r e s u l t s were not used. However, the c h a r a c t e r i s t i c s of the deep water i n Princess Louisa I n l e t have been p l o t t e d on figure 16. I t i s i n t e r e s t i n g to note that the rates of change of temperature and s a l i n i t y between March and May 1963 appear to be the same as between February and March 1963.  The rapid change between February and March was a t t r i b u t e d to  increased mixing i n the deep layer due to the s i n k i n g flood t i d e water.  I n March and May the f l o o d t i d e water was flowing up i n l e t  near the surface and i t was expected that the rates of change o f temperature and s a l i n i t y would decrease.  More data between March  and May might have revealed that the rate of change r e a l l y has decreased.  The oxygen content of the deep layer i n May was s l i g h t l y  lower than i n March.  This i s a t t r i b u t e d to the oxygen demand i n the  water being greater than the supply by downward d i f f u s i o n . The downward d i f f u s i o n had increased i n January .because of the mixing caused by the s i n k i n g f l o o d t i d e water. The temperature and oxygen d i s t r i b u t i o n s i n Sechelt I n l e t were s i m i l a r i n May I963 (not given) to those given f o r July 1961 (figure 19) except that the surface temperature was not as high i n May 1963 nor the oxygen content of the deep layer as low. No middepth oxygen minimum was found but a s l i g h t structure i n the temperature curve i n d i c a t i v e of incomplete f l u s h i n g during the previous  53 winter was noticed. The data f o r J e r v i s I n l e t suggested that the o s c i l l a t o r y motion proposed on page 48 was s t i l l present.  54 References  Carter, N. M.  1934.  Physiography and oceanography of some B r i t i s h Columbia f j o r d s . Proc. 5"th Pac. S c i . Cong., 1933, V o l I , pp 721-733-  G i l m a r t i n , M.  1962.  Annual c y c l i c changes i n the physical oceanography of a B r i t i s h Columbia f j o r d . J . F i s h . Res. Bd. Canada, 19(5)» 921-974*  N ewman, B. G«  1961.  The d e f l e c t i o n of plane j e t s by adjacent boundaries - Coanda e f f e c t . Boundary layer and flow c o n t r o l . Edited by G. V. Lachmann. V o l . I , pp 232-264. Pergamon Press, New York.  Pickard, G. L.  I96I. Oceanographic features of I n l e t s i n the B r i t i s h Columbia mainland coast. Res. Bd. Canada, 18(6)» 907-999.  J . Fish.  Pickard, G. L., and R. W. T r i t e s , 1957. Fresh water transport determination from the heat budget with a p p l i c a t i o n s to B r i t i s h Columbia i n l e t s . J . F i s h . Res. Bd. Canada 14(4)» 605-616. Pickard, G. L., and K. Rodgers, 1959* Current measurements i n Knight I n l e t , B r i t i s h Columbia. J . F i s h . Res. Bd. Canada, 16(5)J 635-678. P r i t c h a r d , D. W. 1952. Estuarine Hydrography. Advances i n geophysics. V o l . I , pp 243-280. Academic Press Inc., New York. Rouse, H.  1959.  Advanced mechanics of f l u i d s . Sons Inc. New York.  John Wiley &  S t r i c k l a n d , J . D. H. and T. R. Parsons, i960. A manual of sea water a n a l y s i s . Fish. Res. Bd. Canada B u l l . No. 125, 185 PPTabata, S., and G. L. Pickard, 1957* The physical oceanography of Bute I n l e t , B r i t i s h Columbia. J . F i s h . Res. Bd. Canada, 14(4)« 487-520. T r i t e s , R. W.  1955.  A study of the oceanographic structure i n B r i t i s h Columbia i n l e t s and some of the determining f a c t o r s . Ph.D. t h e s i s , U n i v e r s i t y of B r i t i s h Columbia, Vancouver, B.C.  T u l l y , J . P.  1949-  Oceanography and p r e d i c t i o n of pulp m i l l p o l l u t i o n i n Alberni I n l e t . F i s h . Res. Bd. Canada B u l l . No. 83, 169 pp.  

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