UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Flood risk and hazard assessment on Lulu Island Jacobs, Paul Arthur 1986

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1986_A7 J33.pdf [ 4.89MB ]
Metadata
JSON: 831-1.0062936.json
JSON-LD: 831-1.0062936-ld.json
RDF/XML (Pretty): 831-1.0062936-rdf.xml
RDF/JSON: 831-1.0062936-rdf.json
Turtle: 831-1.0062936-turtle.txt
N-Triples: 831-1.0062936-rdf-ntriples.txt
Original Record: 831-1.0062936-source.json
Full Text
831-1.0062936-fulltext.txt
Citation
831-1.0062936.ris

Full Text

F l o o d Risk and Hazard Assessment on L u l u I s l a n d By Paul Arthur  Jacobs  B. Sc. Honours, Simon F r a s e r U n i v e r s i t y , 1975 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE  in THE FACULTY OF GRADUATE STUDIES (Department of C i v i l  We accept  Engineering)  t h i s t h e s i s as conforming  to the r e q u i r e d standard  THE UNIVERSITY OF BRITISH COLUMBIA November 1986 © P a u l Arthur Jacobs, 1986  In p r e s e n t i n g  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  requirements f o r an advanced degree a t the  the  University  o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make it  f r e e l y a v a i l a b l e f o r reference  and  study.  I further  agree t h a t p e r m i s s i o n f o r e x t e n s i v e 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 o f  department o r by h i s or her r e p r e s e n t a t i v e s .  my  It i s  understood t h a t copying or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l gain  s h a l l not be  allowed without my  permission.  Department o f The U n i v e r s i t y of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date  a c n w e e - K  t,  written  i i ABSTRACT  L u l u I s l a n d c o n t a i n s most of the M u n i c i p a l i t y of Richmond. Richmond i s a growing community with  100,000  population located  south of the c i t y of Vancouver i n the F r a s e r R i v e r e s t u a r y . The f l o o d hazard  from both the sea and the Fraser R i v e r a r e w e l l  known and to p r o t e c t a g a i n s t i t , an e x t e n s i v e d i k i n g system has been b u i l t . Despite f l o o d hazard  t h i s d i k i n g system a s i g n i f i c a n t  residual  has been c r e a t e d by the e x t e n s i v e development on  the i s l a n d . In a d d i t i o n , concerns have been r a i s e d about p o t e n t i a l f l o o d i n g from earthquake damage and a p r e d i c t e d r i s e in sea l e v e l due t o g l o b a l warming. This t h e s i s analyses  the extent  v a r i o u s sources. New techniques  of the f l o o d hazard  from  of r i s k a n a l y s i s and f i n d i n g s on  r i s k p e r c e p t i o n are used t o examine the f l o o d r i s k . The r o l e of contingency  planning  i s examined. F i n a l l y ,  f o r f l o o d c o n t r o l i n c o n j u n c t i o n with the r o l e of f l o o d insurance  dikes  i s discussed  as a method of p r o v i d i n g i n f o r m a t i o n about f l o o d r i s k l e v e l s t o f l o o d p l a i n users.. Conclusions current  are drawn about the adequacy of  f l o o d c o n t r o l measures and recommendations a r e made to  improve them.  ACKNOWLEDGEMENTS  In the course of t h i s study a s s i s t a n c e was r e c e i v e d from many sources. I am p a r t i c u l a r l y  indebted t o the people i n v o l v e d  in p r o v i d i n g f l o o d p r o t e c t i o n at a l l l e v e l s of government f o r t h e i r time, a c c e s s t o t h e i r documentation, and, most of a l l , f o r s h a r i n g t h e i r e x p e r t i s e with me. From the f e d e r a l government, Sandy D'Aquino,  I would l i k e t o thank Dr.  Jim Leung, N e i l l Lyons, and Jim Oakey of the  Water Planning and Management Branch of Inland Waters. From the B r i t i s h Columbia government,  I would l i k e t o thank  E r i c Bonham, Ron Henry, Robin Round, Sandra Smith, and Jake Wester of the M i n i s t r y of Environment and Parks. From the M u n i c i p a l i t y of Richmond, I would l i k e t o thank Alex Jamieson, Don Mclver, and Henry  Pelzer.  In a d d i t i o n , I would l i k e t o thank my t h e s i s a d v i s o r S. 0. R u s s e l l f o r h i s guidance, c o o p e r a t i o n , and most of a l l f o r h i s careful  listening.  Finally,  I would l i k e t o thank my w i f e , Maruta Jacobs,  her c a r e f u l e d i t i n g and g e n e r a l support.  for  iv TABLE OF  CONTENTS  Abstract  i i  Acknowledgements  i i i  List of Tables  v  List of Figures  vi  Glossary  v i i  Introduction  1  L i t e r a t u r e Review  6  The  34  Flood Hazard  Risk Analysis and Perception Contingency  Planning  48  and Other  Measures  t o R e d u c e Damage  59  Flood.Insurance  65  Conclusions  69  Recommendations  71  Bibliography  73  Appendices  78  - Appendix A - Tables  79  - Appendix B - Figures  85  - Appendix C - Expected  Flood  Damage  C a l c u l a t i o n f o r L u l u I s l a n d ....  90  V  LIST OF  TABLES  I.  Terms f o r C l a s s i f y i n g Hazard P o t e n t i a l s  II.  U. S. A r m y C o r p s E n g i n e e r s H y d r a u l i c E v a l u a t i o n G u i d e l i n e s : R e c o m m e n d e d S p i l l w a y D e s i g n F l o o d s .. 7 9  III.  Value of Commercial Building Permits  IV.  A n n u a l P r o b a b i l i t i e s o f C o m b i n e d F l o o d H a z a r d s .. 8 0  V.  Predicted  VI.  F l o o d Damage E s t i m a t e  VII.  F e d e r a l - P r o v i n c i a l F l o o d Damage Cost Sharing Formula  Changes t o T i d a l Levels for Lulu Island  V I I I . E x a m p l e R u l e o f Thumb F l o o d Protection Level Chart  Issued  79  80  81 81 82 83  vi LIST  OF F I G U R E S  1 . Map o f t h e W e s t e r n E n d o f t h e Lower F r a s e r V a l l e y 2. R i s k - H a z a r d  Perception Rating Chart  86 87  3. M a p o f F u l l T i d a l R e l i e f Z o n e  88  4. R a i s e d R o a d A l i g n m e n t  89  vi i GLOSSARY  C a p i t a t i o n - A method of payment f o r medical  services in which  the p h y s i c i a n r e c e i v e s a f i x e d amount a n n u a l l y for a l l health care services  per  patient  used.  C l i m a t o l o g i c a l Change - A long term, world-wide, warming t h a t has  b e e n p o s t u l a t e d b a s e d on  carbon  dioxide  aspect  of t h i s change from  is the melting in sea  increased  trend  l e v e l s of  i n t h e a t m o s p h e r e . The most s i g n i f i c a n t  of p o l a r  the p o i n t of view of t h i s  ice sheets  and  study  a subsequent  1m  rise  level.  H i g h w a y 99 - T h e  freeway running  c e n t r e of L u l u F l o o d H a z a r d - The  north-south  roughly  through  the  Island. p o t e n t i a l d a m a g e t h a t w o u l d be d o n e  by  flooding. F l o o d R i s k - The  probability that flooding will  L e v e l of P r o t e c t i o n - The event  to withstand.  as e i t h e r an a n n u a l period.  (.005  equivalent Low  p r o b a b i l i t y of occurrence  t h a t dikes or other  designed  Pressure  annual  occur. of a f l o o d  flood control structures  These' p r o b a b i l i t i e s c a n be  p r o b a b i l i t y of occurrence  or a  p r o b a b i l i t y of occurrence  t o a 1 i n 200  year  return  pressures  systems occurring during  the winter  return  period.)  and h i g h w i n d s . The  l e v e l s around L u l u I s l a n d r e s u l t from  expressed  is  S y s t e m s - W e a t h e r s y s t e m s c h a r a c t e r i z e d by  barometric  are  highest  severe months.  low  low tidal pressure  vi ii N o r m a l H i g h T i d e - Any h i g h t i d e t h a t o c c u r s f r o m  the  g r a v i t a t i o n a l p u l l o f t h e s u n a n d t h e moon a l o n e , r a t h e r t h a n i n c o n j u n c t i o n w i t h a low p r e s s u r e MCE  - Maximum C r e d i b l e E a r t h q u a k e  - The  c a n be e x p e c t e d t o o c c u r i n an  system.  largest earthquake  that  area.  M o r b i d i t y - The a v e r a g e number o f p e o p l e s i c k a t any one M o r t a l i t y - The e x p e c t e d number of d e a t h s p e r t h o u s a n d p o p u l a t i o n . For example, the m o r t a l i t y of males  time.  in a  f r o m 45  to  54 i s t h e n u m b e r o f d e a t h s t h a t c a n b e e x p e c t e d t o o c c u r i n a g r o u p o f 1000 m a l e s  45 y e a r s o l d b e f o r e t h e y r e a c h  55  years old. PMF  - P r o b a b l e Maximum F l o o d - A h y p o t h e t i c a l f l o o d d e r i v e d from physical c r i t e r i a that i s the largest flood that could r e a s o n a b l y be e x p e c t e d t o o c c u r .  P o n d i n g - The  f i l l i n g of a d i k e d area to the l e v e l of  e n t e r i n g t h r o u g h a d i k e b r e a c h , c h a r a c t e r i z e d by water  water deeper  l e v e l s than would have o c c u r r e d without the d i k e s  and  a l o s s of v e l o c i t y through the breach. In e f f e c t , the d i k e d a r e a becomes a pond w i t h the d i k e s as P r i m a r y Care - The t y p e of h e a l t h c a r e f i r s t as opposed  banks. s o u g h t by p a t i e n t s  t o h e a l t h c a r e d e l i v e r e d as a r e s u l t of a  r e f e r r a l by a p h y s i c i a n . T y p i c a l e x a m p l e s o f p r i m a r y are the f a m i l y p h y s i c i a n and h o s p i t a l emergency  care  wards.  R i v e r S t a g e - A r i v e r l e v e l w i t h r e s p e c t t o a known datum o r elevation.  ix Spring Freshet  - The  high  r i v e r l e v e l s caused by the  spring  snowmelt. Tidal Relief occurs  - The during  drop i n water l e v e l s around L u l u I s l a n d that low  water l e v e l at low the  dikes.  tide. Full tide  tidal  relief  occurs  when the  i s lower than the land l e v e l  inside  1  INTRODUCTION T h i s i s a study of the  f l o o d hazards and  flood risk  M u n i c i p a l i t y of Richmond, s p e c i f i c a l l y L u l u I s l a n d .  The  M u n i c i p a l i t y of Richmond i s l o c a t e d p r i m a r i l y on L u l u south of the C i t y of Vancouver, in the Province  of  i n the  Island,  British  Columbia. For a f l o o d hazard to e x i s t , two there must be development that can  c o n d i t i o n s must be  be damaged by  met:  inundation  and  there must be a path f o r water to inundate the development. Richmond's l o c a t i o n and  geology have been e x c e l l e n t f o r the  development of a f l o o d hazard. The contains l a n d . The  Province  of B r i t i s h Columbia i s mountainous  relatively  little  existing flat  flat  or a g r i c u l t u r a l l y  l a n d i s concentrated  Most of the r e s t of the p r o v i n c e  and  productive  in river v a l l e y s .  i s made up of steep,  forested  l a n d . As a r e s u l t , most of the land o u t s i d e of s e t t l e d areas i s uninhabited.  The  A t l a s of B r i t i s h Columbia d e s c r i b e s  e x p l a i n s the p o p u l a t i o n  distribution this  and  way:  "Three f e a t u r e s c h a r a c t e r i z e the d i s t r i b u t i o n of p o p u l a t i o n in B r i t i s h Columbia - heavy c o n c e n t r a t i o n i n the southern c o a s t a l lowlands, v a l l e y o r i e n t e d l i n e s of settlement with l a r g e r c l u s t e r s along them i n the southern and c e n t r a l i n t e r i o r and l a r g e areas of unpopulated l a n d . "The  e s s e n t i a l l y unpopulated areas are those which by reason of topography, c l i m a t e , s o i l c o n d i t i o n s , v e g e t a t i v e cover, or r e l a t i v e i s o l a t i o n have o f f e r e d l i t t l e inducement to s e t t l e m e n t . " ( F a r l e y , 1979, p. 4)  In a p r o v i n c e distribution,  with  t h i s type of topography and  population  i t i s no s u r p r i s e that a f l a t area with a m i l d  c l i m a t e , prime a g r i c u l t u r a l  s o i l , and  l o c a t e d w i t h i n easy  2 commuting d i s t a n c e of Vancouver  (metropolitan population  1.2  m i l l i o n ) h a s a t t r a c t e d d e v e l o p m e n t . B e t w e e n 1950 a n d 1960 R i c h m o n d ' s p o p u l a t i o n g r o w t h w a s m o r e t h a n 5% p e r a n n u m . S i n c e then the growth rate has slowed, but i t i s s t i l l approximately 4% p e r a n n u m . M o n e t a r y v a l u e o f f l o o d d a m a g e s was l a s t e s t i m a t e d f o r R i c h m o n d i n 1971. A t t h a t t i m e , t h e p o p u l a t i o n was 62,000 a n d p o t e n t i a l f l o o d damages were e s t i m a t e d a t $100 m i l l i o n . S i n c e 1971, t h e p o p u l a t i o n h a s i n c r e a s e d t o 104,000. I n a d d i t i o n , Richmond has been more c l o s e l y  integrated into the Greater  V a n c o u v e r R e g i o n a l D i s t r i c t ' s economy and has become a major s h o p p i n g a n d w a r e h o u s i n g a r e a . O v e r $500 m i l l i o n o f b u i l d i n g p e r m i t s f o r c o m m e r c i a l d e v e l o p m e n t s have been i s s u e d s i n c e  1971.  Assuming that f l o o d damages would i n c r e a s e p r o p o r t i o n a t e l y w i t h population and i n f l a t i o n ,  t h e maximum f l o o d t h a t t h e d i k e s w e r e  d e s i g n e d f o r , w o u l d c a u s e a b o u t $500 m i l l i o n  i n damage  today  ( 1 9 8 6 ) . S i n c e , a s was m e n t i o n e d a b o v e , t h e c h a r a c t e r o f development has changed, these assumptions are probably conservative. L u l u I s l a n d i s a low l y i n g i s l a n d l o c a t e d i n t h e mouth of the Fraser River e s t u a r y . I t i s susceptible t o flooding  from  b o t h t h e o c e a n a n d t h e F r a s e r R i v e r . I f t h e r e w e r e no d i k i n g system, f l o o d i n g over the whole  island to the 2 foot level  o c c u r f r o m a 1 i n 10 y e a r r e c u r r e n c e p e r i o d f l o o d . H i g h c o u l d be e x p e c t e d t o f l o o d p a r t s o f t h e i s l a n d on s e v e r a l each month.  would  tides days  3 To p r o t e c t a g a i n s t  t h i s f l o o d i n g , 30 m i l e s o f d i k i n g h a v e  been b u i l t . The e a r l i e s t d i k e s on L u l u I s l a n d were b u i l t i n 1876.  Since then  surround  t h e d i k e s have been expanded t o e n t i r e l y  L u l u I s l a n d . The d i k e s have been p e r i o d i c a l l y r a i s e d  and w i d e n e d . The l a s t time  t h e d i k e s were r a i s e d was u n d e r t h e  F e d e r a l - P r o v i n c i a l Agreement o f 1968. Under t h i s agreement, t h e d i k e s were r a i s e d t o p r o v i d e  .6 m e t e r s o f f r e e b o a r d  l e v e l o f a f l o o d w i t h a 1 i n 200 y e a r  recurrence  above the  period.  l e v e l o f p r o t e c t i o n was c h o s e n b e c a u s e t h e 1 i n 200 y e a r  This flood  approximates the largest flood of record. Incidentally, i n several areas  o f t h e F r a s e r V a l l e y , s o i l c o n d i t i o n s make i t  technically difficult higher.  (Wester, 1986, p e r s o n a l  Although areas  (but not impossible)  should  standard  t o b u i l d dikes any  comm.)  c o s t b e n e f i t s t u d i e s were done t o d e t e r m i n e  which  r e c e i v e money t o u p g r a d e t h e i r d i k e s , t h e d e s i g n  f o r t h e d i k e s was s e t p r i m a r i l y f o r p o l i t i c a l a n d  t e c h n i c a l , rather than  economic, reasons.  The design  standard  s e t s t h e r i s k o f f l o o d i n g a t . 0 0 5 p e r y e a r a n d i s now t h e standard  f o r flood p r o t e c t i o n throughout  British  Columbia.  T h e r e a r e s e v e r a l f a c t o r s t h a t make t h e f l o o d s i t u a t i o n on Lulu Island worthy of study been d i s c u s s e d .  a t t h i s time.  The f i r s t has already  There i s a large (and growing) flood hazard i n  Richmond. In f a c t , i t i s the l a r g e s t f l o o d hazard one  of the largest i n North The  second  America.  f a c t o r i s t h a t a new t e c h n o l o g y  assessment has been emerging over technology  has been developed  i n Canada and  of r i s k  the last decade.  mainly  to deal with  This issues  related  4  to the nuclear and  hazardous chemicals i n d u s t r i e s . S p i n - o f f s of  t h i s r e s e a r c h have been a p p l i e d to dam to f l o o d c o n t r o l . The  s a f e t y and  main t h r u s t of t h i s research  determine "How  safe i s safe enough?" T h i s q u e s t i o n  germane, given  the  design  somewhat a r b i t r a r y way  are a p p l i c a b l e i s to is clearly  in which the  current  standards were a r r i v e d a t .  The flooding  t h i r d f a c t o r i s that there  i s concern that the r i s k of  i s i n c r e a s i n g . T h i s concern a r i s e s from the  toward higher  l e v e l s of carbon d i o x i d e  felt  increased  that the  trend  i n the atmosphere. I t i s  l e v e l s of carbon d i o x i d e w i l l  cause  atmospheric warming, which i n turn w i l l melt p a r t s of l a r g e i c e sheets  such as the Greenland i c e sheet.  water thus r e l e a s e d c o u l d w i t h i n the next 50 The  i n c r e a s e sea  I t i s p r e d i c t e d that l e v e l by about 1 metre  years.  f o u r t h f a c t o r i s that some concern has  that the f l o o d r i s k has possibility  been expressed  been underestimated because of  that an earthquake c o u l d l i q u e f y , and  the d i k e s . T h i s concern was  similar soil  widespread s o i l  thus damage,  s t r u c t u r e s to  those found i n Richmond. Both c i t i e s are b u i l t on silty  the  t r i g g e r e d by the earthquake which  s t r u c k N i i g a t a , Japan. N i i g a t a has  compacted sands and  the  poorly  sands. During the N i i g a t a earthquake,  l i q u e f a c t i o n occurred  and  some d i k e s  f a i l e d as a  result. The  final  in the process  f a c t o r i s that the B r i t i s h Columbia government i s of r e v i s i n g i t s f l o o d c o n t r o l p o l i c i e s .  makes the t i m i n g of t h i s t h e s i s f o r t u i t o u s .  This  5  In  an o v e r a l l sense, the management of the f l o o d  in Richmond has been s u c c e s s f u l because has o c c u r r e d s i n c e L u l u I s l a n d was a l a r g e and growing difficulties this  situation  no s i g n i f i c a n t  flooding  developed. The combination of  hazard and both t e c h n i c a l and  political  i n reducing the r i s k make i t worthwhile  to study  situation. T h i s t h e s i s reviews the contemporary  trends i n f l o o d  other hazard p r o t e c t i o n and examines the f l o o d hazard in Richmond i n the l i g h t  of these t r e n d s .  and  situation  6 LITERATURE  The  REVIEW  l i t e r a t u r e a p p l i c a b l e t o t h i s t h e s i s h a s come  several d i f f e r e n t areas.  Since  t h e e a r l y 1970's, a c o n s i d e r a b l e  body o f l i t e r a t u r e has grown up t h a t with  i s s p e c i f i c a l l y concerned  r i s k a s s e s s m e n t . Works w i l l be r e v i e w e d from t h i s a r e a  the s u b j e c t s  of risk perception,  risk analysis i n general,  risk a n a l y s i s applied to water resources Another relevant area has  been used t o evaluate  Fraser  projects  and  in particular.  i s the cost/benefit analysis flood control projects  on  which  i n the lower  Valley.  The and  from  f i n a l area applicable to t h i s thesis i s the  hydrology  geology of Richmond. S p e c i f i c a l l y , works reviewing  earthquake hazard, hazard  the r i v e r flood hazard,  the  and the ocean  flood  w i l l be r e v i e w e d .  Vancouver I n t e r n a t i o n a l Hay and Company (1985)  Airport  This report discusses  Sea  Dykes  the design  Island. Sea I s l a n d i s within  Rehabilitation  of dikes  t o protect Sea  the boundaries of the Municipality  of Richmond, but i s north and west o f L u l u I s l a n d , subject  o f t h i s t h e s i s . The s e c t i o n on h y d r o l o g i c  the main background of  t h i s r e p o r t g i v e s a good d e s c r i p t i o n of the ocean-based hazard  faced by L u l u  The  report  states  -  flood  Island. that:  "Without t h e d i k e s about 85% o f Sea I s l a n d would be inundated during normal high t i d e s , and would s u b s e q u e n t l y be e x p o s e d a t low t i d e s . The n a t u r a l g r o u n d l e v e l s o f t h e l o w l y i n g a r e a s r a n g e f r o m .9 t o 1.5m G S C , j u s t o v e r a m e t r e a b o v e t h e m i d - t i d e l e v e l o f 0.0m G S C " ( H a y a n d C o m p a n y , 1 9 8 5 , p . 1 3 ) . * GSC - G e o d e t i c  Survey of Canada.  7 The  r e p o r t a l s o c a l c u l a t e s t h e e f f e c t o f a 200m  lasting  1 t i d a l c y c l e , i n Sea  done under worst case  conditions,  metres of water would enter a d e p t h of  .7m  Sea  Island,  s t a t e s t h a t 2.8  t o 3.4m  under 85kph winds blowing  f o r a minimum of 6 h o u r s . I t then height  of Sea  Island  i s r e d u c e d by 82%  across  across  the S t r a i t of  requires  puts  and  low  GSC.  The  are  the Island  Island, located  at  at  r e p o r t g i v e s mean h i g h t i d e l e v e l as  t i d e l e v e l a s -3m  GSC.  The  M u n i c i p a l i t y of  1.4m  Richmond  s l i g h t l y lower l e v e l of  1m  Island.  It should  a l s o be n o t e d  that the time i t would take  f l o o d Lulu Island from a storm-caused breach longer  Banks.  b u i l d i n g code in Richmond  t h e mean h i g h t i d e l e v e l a t the  for Lulu  t h a t Sea  to  t h a t a l l u r b a n d e v e l o p m e n t on L u l u I s l a n d be b u i l t  o r a b o v e ,9m GSC  Sturgeon  of L u l u  including almost a l l heavily developed areas, The  reduced  I s l a n d , much of  be n o t e d  Large portions  GSC.  Georgia  S t u r g e o n Banks as a r e s u l t of  description i s applicable. It should  f r o m .9 t o 2.0m  be  s t a t e s t h a t t h i s maximum wave  B e c a u s e L u l u I s l a n d i s c l o s e t o Sea  t i d e s are s l i g h t l y higher.  ocean  waves would  by t h e t i m e i t a p p r o a c h e s t h e d i k e s a c r o s s  elevations  is  discusses  b o t t o m f r i c t i o n . T h i s m e a n s t h a t a 3m w a v e w o u l d b e ,6m  to  land.  report  generated  m i l l i o n cubic  resulting in flooding  f i n a l a p p l i c a b l e part of t h i s study  waves. The  calculation,  s h o w s t h a t 7.4  on a g r i c u l t u r a l l a n d . 85%  agricultural The  I s l a n d d i k e s . The  breach,  b e c a u s e L u l u I s l a n d i s 8.5  no p o n d i n g o c c u r r e d ,  then  w o u l d be  t i m e s as b i g as Sea  to  somewhat Island.  f l o o d i n g t o an a v e r a g e d e p t h of  6cm  If  8 per  t i d a l c y c l e c o u l d be expected from a s i m i l a r dike  breach.  Deeper f l o o d i n g c o u l d be expected in the lowest areas  nearest  the d i k e s , but  i s kept to 1 or 2 t i d a l c y c l e s , the  flooding be  i t i s c l e a r that as long as the d u r a t i o n of ocean  kept to acceptable  f l o o d damage would  levels.  F i n a l l y , while L u l u I s l a n d i s near to Sea  I s l a n d , i t is. f a r  l e s s exposed to wave a c t i o n because almost a l l of L u l u  Island's  western coast  the  reduction  i s protected  by Sturgeon Banks. In f a c t ,  i n wave a c t i o n caused by Sturgeon Banks has made i t  unnecessary to r i p - r a p L u l u I s l a n d sea d i k e s to p r o t e c t them against The  Role  wave a c t i o n . of  Perception  T h i s work provides  in  Flood  Control  -  Gordon  Shanks  an e x c e l l e n t summary of the  (1972)  river  hydrology around L u l u I s l a n d . I t c o r r e c t l y p o i n t s out t h a t largest  f l o o d hazard f a c i n g Richmond i s the one  caused by  s p r i n g f r e s h e t i n v o l v i n g a dike breach i n the e a s t e r n L u l u I s l a n d . In a d d i t i o n , Shanks p r o v i d e s of the a t t i t u d e s and  perceptions  the of  detailed descriptions  toward the  the government o f f i c i a l s concerned with  end  the  f l o o d hazard of both  f l o o d c o n t r o l and  the  p u b l i c l i v i n g on L u l u I s l a n d . HYDROLOGY OF  LULU ISLAND  L u l u I s l a n d i s l o c a t e d i n the F r a s e r R i v e r E s t u a r y . r i v e r branches and The  eastern  end  forms s e v e r a l channels around L u l u  of L u l u I s l a n d i s t o t a l l y  environment, while  the western end,  i s i n a marine environment. The  Island.  riverine  f r o n t i n g on Georgia  general  s e p a r a t i n g areas under r i v e r i n e and  in a  The  Strait,  east-west d i v i d i n g l i n e  t i d a l based f l o o d hazard i s  9 shown. The  areas under t i d a l  i n f l u e n c e are not t r e a t e d i n t h i s  work. F l o o d i n g from a dike breach d u r i n g the s p r i n g f r e s h e t i s i d e n t i f i e d as the l a r g e s t  f l o o d hazard. The work c o r r e c t l y  s t a t e s that a major dike break, from t h i s cause,  would f l o o d  the  whole i s l a n d . I t a l s o s t a t e s that f l o o d i n g would occur to the same l e v e l as i f there were no d i k e s . The average f l o o d i n g l e v e l for  a 1 i n 200  year  flood  i s given as 4 feet  (1.2m).  DIFFICULTIES WITH DIKING SYSTEMS Several d i f f i c u l t i e s  i n the dependence on d i k i n g systems to  p r o t e c t urban areas from f l o o d i n g are d e s c r i b e d . These i n c l u d e : - The  difficulty  i n b u i l d i n g d i k e s high enough to provide  complete p r o t e c t i o n from - The  overtopping.  i m p o s s i b i l i t y of b u i l d i n g d i k e s that are  completely  safe from extreme f l o o d i n g events. Problems from b o i l s , u n d e r c u t t i n g , p i p i n g , and underseepage can occur even with w e l l maintained extreme - The  dikes during  events.  i m p o s s i b i l i t y of m a i n t a i n i n g dikes to 100% standard. Dikes  of  s e t t l e , are damaged by bank e r o s i o n  and other l e s s obvious animals  these  f a c t o r s such as burrowing  over time. As a r e s u l t , constant  r e p a i r s are  necessary. - The  f a c t that a major break i n the d i k e s would cause f l o o d i n g of the whole i s l a n d making the d i k e s u s e l e s s .  10 - The tendency  f o r d e v e l o p m e n t t o grow up b e h i n d  When d i k e s f a i l , t h e damage i s g r e a t e r t h a n have been i f d i k e s had n o t been  dikes. i t would  built.  P R O B A B I L I T I E S OF F L O O D I N G When t h i s work was w r i t t e n t h e d e s i g n  standard  f o r Richmond  d i k e s was t h e 1948 f l o o d p l u s two f e e t o f f r e e b o a r d . I t i s stated that the p r o b a b i l i t y of overtopping The a u t h o r  p o i n t s out that, over a design  probability of overtopping  i s .005 p e r annum. l i f e o f 50 y e a r s , t h e  the dikes under these c o n d i t i o n s i s  .22. P E R C E P T I O N OF FLOOD The  HAZARD  discussion of flood hazard  perception  i s divided into 2  parts: the perception of involved government o f f i c i a l s and the perception of the public living  i n R i c h m o n d . I t was f o u n d  that  t h e r e i s a l a r g e v a r i a t i o n i n how s e r i o u s t h e f l o o d h a z a r d  was  p e r c e i v e d t o be among g o v e r n m e n t o f f i c i a l s . A g r a d a t i o n i n concern  was n o t e d  from  federal o f f i c i a l s to municipal  officials.  Shanks w r i t e s : " F e d e r a l o f f i c i a l s who h a v e t h e l e a s t d i r e c t i n p u t c o n s i d e r t h e p r e s e n t h a z a r d t o b e a s i g n i f i c a n t o n e . On t h e o t h e r h a n d , t h e m u n i c i p a l l e v e l o f f i c i a l s who a r e t h e most d i r e c t l y i n v o l v e d with implementation of f l o o d management p o l i c i e s f a i l t o p e r c e i v e t h e f l o o d h a z a r d as b e i n g s i g n i f i c a n t . " (Shanks, 1968, p. 94) O f f i c i a l s p e r c e i v e d d i k i n g a s t h e most s u i t a b l e to  the flood hazard  and upstream storage as t h e next  adjustment most  s u i t a b l e a l t e r n a t i v e . These measures c o n t r o l the f l o o d r i s k , not the f l o o d hazard.  There  control the flood hazard restrictions.  was l i t t l e  support  f o r solutions that  such as f l o o d p r o o f i n g and land use  11 T h i s work found t h a t  the p u b l i c  recognized the  possibility  of f l o o d damage (52% of r e s p o n d e n t s ) , but d i d not e x p e c t experience flooding author states that  to  i n t h e i r l i f e t i m e (85% of r e s p o n d e n t s ) . t h i s i s a low l e v e l of f l o o d  The  hazard  perception. T h i s work found t h a t the p u b l i c  is essentially indifferent  t o t h e f l o o d h a z a r d a n d t h a t , by d e f a u l t , p o l i c y i s made by professionals  i n f l o o d c o n t r o l . As t h e a u t h o r  the  states:  " I n d i c a t i o n s a r e t h a t p u b l i c s u p p o r t w o u l d n o t be a decisive factor in affecting flood adjustments." ( S h a n k s , 1968, p . 108) S i n c e t h i s s t u d y was  performed,  t o t h e 1 i n 200 y e a r l e v e l p l u s probable that the flood  the d i k e s have been  2 feet of f r e e b o a r d . I t i s  r a i s i n g the d i k e s d e c r e a s e d p u b l i c awareness of  hazard.  I t s h o u l d be n o t e d t h a t t h e p r o b a b i l i t y o f no occurring  raised  i n t h e n e x t 40 y e a r s i s 8 2 % . *  In view of the l e n g t h  t i m e p e o p l e c a n be e x p e c t e d t o l i v e i n one p l a c e , lack of concern about  flooding  the f l o o d hazard does not  the  of  public's  seem  unreasonable. The  sense of the author's argument i s that  i f government  o f f i c i a l s f i n d that d i f f e r e n t f l o o d c o n t r o l methods such floodproofing  or s t r i c t e r zoning are necessary, the  probably would not  as  public  object.  F i n a l l y , S h a n k s was were the most concerned  unable to explain about  why  federal  the f l o o d hazard while  officials  provincial  * T h e p r o b a b i l i t y o f n o f l o o d o c c u r r i n g i n 40 y e a r s g i v e n p r o b a b i l i t y o f f l o o d i n g i s .005 i s (1 - . 0 0 5 ) = .818 . 4 0  annual  12 o f f i c i a l s were l e s s concerned and l e a s t concerned. No responsibility  attempt was  municipal  o f f i c i a l s were the  made to c o r r e l a t e the  l e v e l of  f o r payment of f l o o d damages with l e v e l  of  concern about f l o o d i n g . E a r t h q u a k e D e s i g n i n R i c h m o n d , B.C. P e t e r M. B y r n e and D o n a l d L. A n d e r s o n  (1983)  T h i s work documents the earthquake hazard faced  by  Richmond. Richmond i s l o c a t e d i n the c i r c u m p a c i f i c b e l t w e l l known f o r i t s earthquake a c t i v i t y . I t o u t l i n e s the underlying  soils  i n c r e a t i n g the p o t e n t i a l f o r high  r o l e of  the  earthquake  hazard. I t i s s t a t e d that w a t e r - s a t u r a t e d l o o s e - to medium-dense sands and  s i l t s are prone to s t r e n g t h  when exposed to strong  shaking.  T h i s paper d e s c r i b e s of sand as  l o s s through l i q u e f a c t i o n  the process of l i q u e f a c t i o n  follows:  " I f a l l the load i s t r a n s f e r r e d to the water, the s o i l l o s e s a l l of i t s s t r e n g t h and behaves l i k e a l i q u i d and i s s a i d to have l i q u e f i e d . The high water p r e s s u r e s can l e a d to e x p u l s i o n of water and sand at the ground s u r f a c e i n the form of miniature volcanoes and the l o s s of s t r e n g t h can r e s u l t in l a r g e movements of s t r u c t u r e s and s e r v i c e s founded i n or above the l i q u e f i e d zone. Such behaviour has been noted r e p e a t e d l y d u r i n g earthquake shaking where the u n d e r l y i n g s o i l s are comprised of loose s a t u r a t e d s o i l s (Youd, 1975). R e s u l t i n g earthquake damage has g e n e r a l l y been much more severe i n areas u n d e r l a i n by such s o i l s . " (Byrne, 1985, p. 3) The flooding  e s s e n t i a l p o i n t s made i n t h i s paper with respect  to  i n Richmond a r e :  - Richmond s o i l s are loose - The  to medium dense sands and  silts.  d i k e s around Richmond are made of the ..same m a t e r i a l s .  13  - The h i g h water t a b l e i n Richmond ensures that the dike foundations constantly - The  soils  and  the lower p a r t of the d i k e s are  saturated.  found  in both the s u r f a c e s o i l  d i k e s are of the type that i s l i k e l y  l a y e r s and to l i q u e f y  the in a  s t r o n g earthquake. - An earthquake l i k e l y  to cause l i q u e f a c t i o n would have a  r e t u r n p e r i o d of 475 - The  years.  upper p o r t i o n s of the d i k e s are only s a t u r a t e d d u r i n g extreme high t i d e s or the s p r i n g f r e s h e t . Consequently the p r o b a b i l i t y of l i q u e f a c t i o n of the t o t a l  height of  the d i k e s i s q u i t e s m a l l . - Even i f only the base of the d i k e s and liquefy, occur - The  l o n g i t u d i n a l and  the  foundations  transverse cracks could  i n the d i k e s .  f l o o d i n g that would occur under the most c o n d i t i o n s would be from t i d a l relief to  sources. The  likely tidal  d u r i n g low t i d e would allow r e p a i r s to be made  the d i k e s under dry c o n d i t i o n s . I f r e p a i r s to the  d i k e s were not completed q u i c k l y , s e r i o u s f l o o d i n g would - The  result.  p r o b a b i l i t y of an earthquake o c c u r r i n g d u r i n g  the  high water l e v e l s of the s p r i n g f r e s h e t i s so small that the p o s s i b i l i t y  can be c o n s i d e r e d  negligible.  14 E s t i m a t i n g F l o o d Damages i n t h e F r a s e r R i v e r B a s i n A r c h i e N. Book a n d Romeo P r i n c i c ( 1 9 7 5 ) T h i s work c o n t a i n s t h e m e t h o d o l o g y a n d r e s u l t s o f t h e l a s t comprehensive estimate River Basin  of p o t e n t i a l  ( i n c l u d i n g R i c h m o n d ) . As t h i s  only with estimating p o t e n t i a l given  f l o o d damage i n t h e F r a s e r  in this  structures are typically  to protect against a  f l o o d " and t h a t t h e s i z e of t h e d e s i g n than  flood  permits  In p a r t i c u l a r ,  rational  criteria.  i s that  i t i s now  i n Richmond i n t h e  $500 m i l l i o n  of b u i l d i n g  f o r c o m m e r c i a l u s e s h a v e been i s s u e d s i n c e 1 9 7 1 .  This  study  identifies  4 t y p e s o f f l o o d damage: l o s s o f  p r o p e r t y and income, r i s k - t a k i n g , on  study  o l d . Much d e v e l o p m e n t h a s o c c u r r e d  "design  i susually  economically  A major problem w i t h t h e r e s u l t s of t h i s  intervening years.  l e v e l s of f l o o d  however, t h a t f l o o d c o n t r o l  designed  d e t e r m i n e d by methods o t h e r  i s concerned  f l o o d damages, no g u i d a n c e i s  r e p o r t a s t o what a p p r o p r i a t e  p r o t e c t i o n are. I t i s noted,  15 y e a r s  study  i n t a n g i b l e s , and r e s t r i c t i o n s  t h e use of t h e f l o o d p l a i n .  MEASUREMENT OF RISK-TAKING Risk-taking  i s measured as t h e d i f f e r e n c e between t h e l e v e l  o f p r o t e c t i o n s p e c i f i e d by p o l i t i c a l  decree and t h e l e v e l  w o u l d be o p t i m a l on t h e b a s i s o f m a r g i n a l are given  that  analysis. Intangibles  o n l y minor c o n s i d e r a t i o n .  INTANGIBLES This injuries, of l i f e normally  report l i s t s  i n t a n g i b l e damages a s l o s s o f l i f e ,  p s y c h o l o g i c a l d i s t u r b a n c e s , and s o c i a l u p h e a v a l .  and i n j u r i e s a r e d i s c o u n t e d do n o t r e s u l t  Loss  because deaths and i n j u r i e s  from f l o o d i n g i n t h e F r a s e r V a l l e y and i t  15 i s unclear  that s t r u c t u r a l f l o o d c o n t r o l measures prevent e i t h e r  deaths or i n j u r i e s . Given the slow r i s e  in r i v e r l e v e l s that  occurs in the F r a s e r V a l l e y , these o b s e r v a t i o n s l i k e l i h o o d of deaths and Psychological considered  i n j u r i e s are  disturbances  and  about  reasonable.  s o c i a l upheaval are  because they are d i f f i c u l t  the  not  to determine i n monetary  terms. COST OF  RISK-TAKING  The  c o s t of r i s k - t a k i n g i s d e f i n e d as the premium people  are w i l l i n g to pay f l o o d . The  report  to a v o i d very  large losses in a catastrophic  suggests that t h i s premium equals the  in p r o t e c t i o n l e v e l s s p e c i f i e d , over what would be  excess  s p e c i f i e d by  s e t t i n g marginal c o s t s of p r o t e c t i o n equal to marginal  benefits  from p r o t e c t i o n . PROPERTY AND The  INCOME LOSSES  main focus of t h i s r e p o r t  i s on property  and  income  losses. Three types of f l o o d p l a i n usage were found to significantly  contribute  to p o t e n t i a l f l o o d damages:  - R e s i d e n t i a l usage. - Commercial and i n d u s t r i a l - A g r i c u l t u r a l usage.  usage.  R e s i d e n t i a l Usage T h i s study found that s l i g h t l y  l e s s than h a l f of a l l  p o t e n t i a l f l o o d damages i n the F r a s e r V a l l e y are residential Given the  l o s s e s . For Richmond, i t was  2/3  increase  s l i g h t l y more than  in Richmond's p o p u l a t i o n  p o t e n t i a l f o r t h i s type of damage has  from  since  1971,  c e r t a i n l y increased.  50%. the  16 Commercial and Extensive commercial and  I n d u s t r i a l Usage surveys were performed to determine p o t e n t i a l industrial  f l o o d damage. Commercial  activities  were grouped to f a c i l i t a t e c a l c u l a t i o n of f l o o d damage. Each i n d u s t r i a l a c t i v i t y was  surveyed to determine p o t e n t i a l f l o o d  damage. These a c t i v i t i e s accounted f o r 16% of p o t e n t i a l damages in the F r a s e r Basin and value  23%  i n Richmond. I t i s c l e a r from the  of b u i l d i n g permits issued that commercial a c t i v i t y  increased g r e a t l y i n Richmond s i n c e however, to repeat  the e x t e n s i v e  determine an accurate  1971.  I t would be  survey r e p o r t e d  f i g u r e for these usage  has  necessary,  i n t h i s work to  types.  A g r i c u l t u r a l Usage The  report l i s t s  the probable a g r i c u l t u r a l  f l o o d damages  as: "crop and equipment l o s s e s , r e d u c t i o n s i n p r o d u c t i v e c a p a c i t y of l i v e s t o c k , premature s l a u g h t e r i n g of p o u l t r y , and the c o s t s of e x t r a feed to r e p l a c e that l o s t during a f l o o d " (Book and P r i n c i c , 1975, p. 62). T h i s type of a c t i v i t y accounted f o r 16% of p o t e n t i a l f l o o d damage i n the F r a s e r B a s i n , but  only 5%  i n Richmond.  SUMMARY Because of the urbanized I s l a n d i n 1971,  nature of development on  a l a r g e f l o o d hazard was  toward u r b a n i z a t i o n , has  i f anything,  i n c r e a s i n g l e v e l s of u r b a n i z a t i o n  Lulu  i d e n t i f i e d . The  increased  s i n c e then can  trend  s i n c e 1971.  The  only have  i n c r e a s e d the hazard. As a thorough documentation of the s i z e of the L u l u I s l a n d f l o o d hazard, the authors' this thesis.  work i s r e l e v a n t  to  1 7  The  major l i m i t a t i o n  i n t a n g i b l e and  of the  report  r i s k - t a k i n g c o s t s . By d e f i n i n g r i s k - t a k i n g cost  as the premium people are w i l l i n g a n a l y s i s would suggest, the the a v e r s i o n  i s i t s treatment of  f e l t against  to pay  over what marginal cost  report neglects  the p o s s i b i l i t y  extremely l a r g e l o s s e s occurs because  these l o s s e s would l e a d to s o c i a l upheaval and S a f e t y o f Dams: F l o o d and E a r t h q u a k e C r i t e r i a C o m m i t t e e on S a f e t y C r i t e r i a f o r Dams (1985) T h i s work reviews c u r r e n t r e s i s t extreme h y d r o l o g i c identifies reservoir  two  Reservoir  and  dam  disruption. -  p r a c t i c e s in designing seismic  types of f a i l u r e d u r i n g  f a i l u r e and  events. I t  dams to  clearly  extreme f l o o d i n g events:  failure.  f a i l u r e occurs when there  is insufficient  r e s e r v o i r c a p a c i t y to s t o r e inflow waters behind a dam. protect  the dam  and  To  prevent a sudden r e l e a s e of a l l the water  s t o r e d behind the dam, hydrologic  that  water i s routed  events can cause the  over a s p i l l w a y . Extreme  r e l e a s e of s u f f i c i e n t  flows over  the s p i l l w a y to cause f l o o d damages approaching or even exceeding those that would have occurred  i f the dam  had  not  been  of the  dam.  built. Dam  f a i l u r e occurs when the  insufficient A dam  spillway capacity  to prevent overtopping  and/or breaching  f a i l u r e can cause f l o o d damages much g r e a t e r  have been experienced i f no dam l a r g e magnitude event can  had  been p r e s e n t .  than would A rare  cause e i t h e r type of f a i l u r e .  work i s mainly concerned with dam fa i l u r e .  is  f a i l u r e rather  and This  than r e s e r v o i r  18 T h i s r e p o r t makes s e v e r a l u s e f u l p o i n t s concerning s a f e t y should o b j e c t i v e as "The  be designed i n t o a dam.  I t s t a t e s the  how  much  design  follows:  o b j e c t i v e should be to balance the b e n e f i t s of making dams s a f e r a g a i n s t the c o s t of the i n c r e a s e d s a f e t y and to reduce any r i s k s to acceptable proportions." (Committee on Safety of Dams, 1985, p. 9)  I t s t a t e s that government must decide what i s an l e v e l of r i s k  for involuntary  acceptable  hazards where i t a c t s as the agent  for groups of people. Several  f a c t o r s are c i t e d that have made i t d i f f i c u l t  government to decide what i s an a c c e p t a b l e lack of p r e c i s i o n and magnitude h y d r o l o g i c  r i s k . These i n c l u d e a  accuracy i n the p r e d i c t i o n of events, the  i n t a n g i b l e s such as l o s s of l i f e  for  inability  large  to e a s i l y  f a c t o r in  i n t o c a l c u l a t i o n s , and  the  p o s s i b i l i t y that f u t u r e downstream development might significantly  i n c r e a s e the hazard a f t e r a dam  is built.  T h i s work, a l s o , suggests that the c o s t s of s a f e t y to t o t a l p r o j e c t c o s t are  important  i n making design  relative  trade-offs:  "For example, i f only a t i n y a d d i t i o n to the cost of b u i l d i n g the dam would be r e q u i r e d to design to a higher standard, t h i s g r e a t e r standard makes sense. S i m i l a r l y , i f the cost of d e s i g n i n g to the PMF and MCE are very l a r g e in r e l a t i o n to a s l i g h t l y l e s s s t r i n g e n t design, c a r e f u l c o n s i d e r a t i o n must be given to whether the more s t r i n g e n t design i s needed." (Committee on Safety of Dams, 1985, p. 14) The  current  design  p r a c t i c e s reviewed by t h i s work show  that most j u r i s d i c t i o n s use classification  a relatively  simple hazard  scheme to decide on a p p r o p r i a t e  Table I at the end  of t h i s t h e s i s ) . Minimum  *PMF - Probable Maximum F l o o d . MCE Earthquake.  risk levels.  discharge  - Maximum C r e d i b l e  (See  19  c a p a c i t i e s , which are u s u a l l y q u i t e s t r i n g e n t , are s e t . T h i s work d e s c r i b e s  s e v e r a l s i t u a t i o n s under which these c o n d i t i o n s  might be r e l a x e d to a l e s s s t r i n g e n t d i s c h a r g e situations and  i n c l u d e r e - e v a l u a t i o n of e x i s t i n g high hazard dams  e v a l u a t i o n of low and intermediate It  hazard dams.  i s suggested that r i s k a n a l y s i s techniques  determine r e q u i r e d discharge two d i s t i n c t The  c a p a c i t y . These  capacity  be a p p l i e d to  i n these s i t u a t i o n s and  types of r i s k a n a l y s i s are d e s c r i b e d .  first  technique i n v o l v e s determining  v a r i o u s s p i l l w a y designs  the c o s t s of  and the a s s o c i a t e d long term damages  ( r i s k c o s t ) . The s p i l l w a y c a p a c i t y chosen would be the one with the lowest t o t a l c o s t . I t was proposed that c o s t s with  l o s s of l i f e  associated  be t r a n s l a t e d i n t o monetary amounts based on  recent c o u r t d e c i s i o n s . T h i s approach has not been widely  accepted  because:  - There i s r e l u c t a n c e t o p l a c e a monetary value on human life. - The present  value c a l c u l a t i o n s i n an economic a n a l y s i s  are dependent on the i n t e r e s t r a t e s e l e c t e d . I t i s felt  that the choice  - Estimates the  of i n t e r e s t r a t e i s a r b i t r a r y .  of average annual r i s k c o s t s are dependent on  f l o o d frequency curve adopted. Estimates  of the  frequency of rare f l o o d events are i n a c c u r a t e . (The frequency f o r a given  s i z e event has been observed t o  i n c r e a s e over time as more data  is collected).  ... The second technique i n v o l v e s choosing  the f l o o d flow f o r  which f a i l u r e of the dam would cease t o c r e a t e  significant  20 a d d i t i o n a l damage downstream. T h i s technique i s more i n l i n e with c u r r e n t l e g a l and p r o f e s s i o n a l p r a c t i c e ,  i n that  i t ensures  that damage would be no g r e a t e r than i f the dam had not been built. One  problem mentioned, with t h i s approach,  possibility  that  i s the  i n c r e a s e d downstream development a f t e r the dam  i s b u i l t c o u l d make the expected s p i l l w a y c a p a c i t y  inadequate.  T h i s technique i s p a r t i c u l a r l y a p p l i c a b l e to the review of e x i s t i n g high hazard dams. For these dams i t i s o f t e n found that the s p i l l w a y because  i s inadequate to pass the probable maximum  flood  the s i z e of the probable maximum f l o o d has been r e v i s e d  upward. For  low hazard and i n t e r m e d i a t e hazard dams t h i s  appears t o r e l a x the c r i t e r i a  report  further:  "Safety e v a l u a t i o n s f o r i n t e r m e d i a t e - and low-hazard dams are p r i m a r i l y concerned with the economic e f f e c t s of t h e i r p o t e n t i a l f a i l u r e s . However, a c o n t i n u i n g problem with such e v a l u a t i o n s i s the a c t u a l or p o t e n t i a l development of the area downstream from the dam a f t e r the dam i s c o n s t r u c t e d and the consequent change i n the hazard r a t i n g s f o r the p r o j e c t . " (Committee on S a f e t y of Dams, 1985, p. 102) The  low- and i n t e r m e d i a t e - h a z a r d dam break e v a l u a t i o n s a r e  not very f a r removed from the n a t u r a l f l o o d c o n t r o l  evaluation.  Some d i f f e r e n c e s do e x i s t , however. The p r i n c i p a l d i f f e r e n c e i s that a l l dam breaks v e l o c i t i e s , deeper  i n v o l v e higher h y d r a u l i c head, higher water f l o o d waters, and r a p i d f l o o d i n g . A l l of  these f a c t o r s make the p r o b a b i l i t y of l o s s of l i f e high i f any development e x i s t s  immediately downstream of a dam. T h i s i s not  the case with most f l o o d s i t u a t i o n s . In p a r t i c u l a r , i s not probable from the f l o o d i n g of L u l u I s l a n d .  l o s s of l i f e A second  21  difference  i s that dams a r e b u i l t and operated by someone. I f a  dam f a i l s , whoever b u i l t resulting  i t can expect to have t o account f o r  f l o o d damage. F i n a l l y , the b u i l d i n g of dams does not  n e c e s s a r i l y a c t as a c a t a l y s t to development on the f l o o d p l a i n . The  p o s s i b i l i t y that  f u t u r e development might i n c r e a s e the  hazard i s e s p e c i a l l y important most dam p r o j e c t s ,  f o r f l o o d c o n t r o l because,  flood control projects  increase  unlike  the hazard by  f o s t e r i n g development. Another important p o i n t  with respect  to flood control i s  the high incremental c o s t s when e f f o r t s a r e made to reduce the r i s k of f l o o d i n g to very small for  dams where the cost  p r o b a b i l i t i e s . This  of a s p i l l w a y  per u n i t  i s not true  discharge  decreases as the c a p a c i t y  of the s p i l l w a y  d i f f e r i n g cost  make i t expensive t o a v o i d  assessing  structures  i n c r e a s e s . The the task of  r i s k s f o r the f l o o d hazard by making those r i s k s very  small. On the other hand, there are many s i m i l a r i t i e s between the two  s i t u a t i o n s . Both r e s u l t i n f l o o d damage. In both cases not  all  f l o o d damage can be c a l c u l a t e d . In p a r t i c u l a r , the s o c i a l  upheaval from a n a t u r a l subject  flood i s d i f f i c u l t  to the i n a c c u r a c i e s  to q u a n t i f y .  i n determining frequencies  Both a r e of r a r e  f l o o d i n g events. F i n a l l y , although no one i s r e s p o n s i b l e f o r natural for  f l o o d i n g , governments u s u a l l y  aiding  flood  take some r e s p o n s i b i l i t y  victims.  On the whole, dam breaks are a more s e r i o u s natural  hazard than  f l o o d i n g , but the two hazards a r e s i m i l a r enough that  22  the methods used to evaluate some m o d i f i c a t i o n s ,  The  fatal  accidents  s o c i a l cost  i s perceived  producing the  same number of  fatalities,  1.  i s perceived  i s not  number of f a t a l i t i e s . The  can  with which  n e c e s s a r i l y r e l a t e d to  article  of an a c c i d e n t  that a c c i d e n t s  of  to be more s e r i o u s than  second model suggests that the s e r i o u s n e s s  seriousness  (1984)  I t i s commonly suggested that  a  that a >  an a c c i d e n t  To  models of how  i s a f u n c t i o n of N .  many small a c c i d e n t s  The  two  f i r s t model suggests that the  a s i n g l e large accident  The  -  S a r a h L i c h t e n s t e i n , and B a r u c h F i s c h o f f  are p e r c e i v e d .  implying  be a p p l i e d , with  Impact of F a t a l A c c i d e n t s  This a r t i c l e considers  N lives lost  breaks can  to n a t u r a l f l o o d hazards.  M o d e l l i n g the S o c i e t a l Paul Slovic,  dam  i n s t e a d suggests that  be a t t r i b u t e d i n p a r t  the the  to the  fact  are s i g n a l s of f u t u r e t r o u b l e . I t s t a t e s t h a t :  s o c i e t a l impact of an a c c i d e n t i s determined to an important degree by what i t s i g n i f i e s or portends. a c c i d e n t that causes l i t t l e d i r e c t harm may have immense consequences i f i t i n c r e a s e s the judged p r o b a b i l i t y and s e r i o u s n e s s of f u t u r e a c c i d e n t s . " ( S l o v i c e t . a l . , 1984, p. 464)  An  support t h i s model, the authors c i t e s e v e r a l s t u d i e s i n  which people were asked to c h a r a c t e r i z e the r i s k s from s e v e r a l sources - i n c l u d i n g nuclear  power. I t was  of these s t u d i e s c o u l d be e x p l a i n e d and  by two  found that the r e s u l t s f a c t o r s , unknown r i s k  dread r i s k . Unknown r i s k s are those which a r e :  observable,  not  unknown to those exposed, delayed i n t h e i r  effects,  new, and unknown to s c i e n c e . Dread r i s k s are those which a r e : u n c o n t r o l l a b l e , g l o b a l c a t a s t r o p h i c , f a t a l , not e q u i t a b l e , of  23 high r i s k to f u t u r e g e n e r a t i o n s , not e a s i l y reduced, i n v o l u n t a r y , and p e r s o n a l l y a f f e c t The  the  increasing,  respondent.  r i s k s a s s o c i a t e d with n u c l e a r power were found to be  q u i t e h i g h i n both of these c a t a g o r i e s . T h i s a r t i c l e does not s p e c i f i c a l l y cover the f l o o d hazard, but i t does c o n s i d e r the risk  from l a r g e dams. Large dams are p e r c e i v e d to be known but  dread r i s k s . As the same technology i s used to c o n t a i n f l o o d s as to b u i l d dams, but the p r o b a b i l i t y of f a t a l i t i e s most f l o o d i n g than d u r i n g a dam c l a s s i f i e d as non-dread, a slightly  break,  i s l e s s during  f l o o d s should be  known r i s k s . Thus, t h i s model suggests  r i s k - p r o n e a t t i t u d e toward  flooding.  Shank's f i n d i n g that people i n Richmond are at most indifferent  to the f l o o d hazard supports t h i s view. The  government's p o l i c y that a l l f l o o d c o n t r o l works be cost j u s t i f i e d a l s o supports t h i s  federal  strictly  view.  In e f f e c t , t h i s p o l i c y s t a t e s that expected f l o o d damages (net b e n e f i t s ) must exceed the amount spent to a v o i d the damages (expected p r o j e c t c o s t s ) . In a d d i t i o n , because  of the  l e v e l of p r o t e c t i o n p r o v i d e d i n B r i t i s h Columbia protection  year  r a t i o s have been higher f o r urban  than r u r a l ones. A f l o o d cause  ( a l l flood  i s designed to p r o t e c t up to the 1 i n 200  level), benefit-cost  fixed  areas  i n an urban area such as Richmond would  f a r more damage than a f l o o d  i n a r u r a l area having f a r  l e s s p o p u l a t i o n and development. Current p o l i c y spends l e s s f o r each d o l l a r of damages i n areas with higher expected  flood  damages than i n areas with lower p o t e n t i a l damages. Current policy  i s , in e f f e c t ,  r i s k - p r o n e toward  larger  flood  risks.  24 R i s k P e r c e p t i o n : A S y s t e m a t i c Review of C o n c e p t s and R e s e a r c h R e s u l t s - O r t w i n Renn. (From " A v o i d i n g and M a n a g i n g E n v i r o m e n t a l Damage f r o m M a j o r A c c i d e n t s " ) (1985)  T h i s paper perception.  r e v i e w s t h e s t a t e o f t h e a r t knowledge i n r i s k  I t p r e s e n t s a number o f c o n c e p t s  assessing attitudes to the flood It  that are useful i n  hazard.  s t a t e s t h a t , g e n e r a l l y , p e o p l e do a g o o d j o b i n  assessing risks that are familiar.  Low r i s k s ,  be u n d e r e s t i m a t e d  t e n d t o be o v e r e s t i m a t e d .  When a r i s k ability  while high risks  i s o u t s i d e of normal  t o determine  e x p e r i e n c e , few p e o p l e h a v e t h e  even t h e o r d e r o f m a g n i t u d e o f t h e r i s k s  i n v o l v e d . Examples g i v e n  include:  - The number o f l i v e s event  however, tend t o  likely  t o be l o s t  i n a catastrophic  t h a t o c c u r s once i n a l i f e t i m e .  are graded  almost  Either a l l risks  u n i f o r m l y or e x o r b i t a n t estimates  a r e made. - D i s a s t e r s expected  at long i n t e r v a l s  An i m p o r t a n t  r e p o r t e d i n t h i s paper  finding  presumed l o s s r a t e s a r e p r a c t i c a l l y perception.  I n o t h e r words, people  ( 8 0 t o 100 y e a r s ) .  independent do n o t a s s e s s  a c c o r d i n g t o presumed l o s s e s p e r y e a r . Expected have o n l y s l i g h t  explanatory value i n predicting  i s that of r i s k hazards l o s s e s per year risk  percept ion. The m i n i m a l perception  p r e d i c t i v e value of expected  i spartially  e x p l a i n e d by t h e f a c t  l o s s e s on r i s k t h a t most  are not f a m i l i a r with the r a t i o n a l e of p r o b a b i l i t y When p r o b a b i l i t i e s a r e n o t i n t u i t i v e l y perceived riskiness  i slikely  people  estimates.  understandable, the  t o be r e l a t e d t o t h e w o r s t  25 imagined a c c i d e n t . Media coverage s e n s a t i o n a l i z e s the worst imagined a c c i d e n t :  i . e . , tends to make i t seem more probable and  more s e r i o u s than i t i s . Another point made i n t h i s a r t i c l e i s that people do not perceive  r i s k d i r e c t l y . They see options  have b e n e f i t s and r i s k s attached them d i r e c t l y , distributes  or p o s s i b i l i t i e s that  t o them. I f an o p t i o n  benefits  people w i l l accept more r i s k than i f the option  b e n e f i t s and r i s k s e q u a l l y throughout s o c i e t y . I f  the o p t i o n does not b e n e f i t them, but imposes r i s k s on them, people w i l l p e r c e i v e  the r i s k very  stongly.  Hazards that pose a pending danger are p e r c e i v e d  as more  s e r i o u s than hazards that come at p r e d i c t a b l e times. T h i s because the dangerous s i t u a t i o n Two other  i s so  c o u l d occur at any time.  f a c t o r s which i n f l u e n c e r i s k p e r c e p t i o n ,  after  the debate on a hazard has been p o l i t i c i z e d , are mentioned. A person's value will  o r i e n t a t i o n and general  influence risk perception.  This  attitudinal  i s especially  true  system  i f the  debate on the hazard has become p o l i t i c i z e d . In a d d i t i o n , the c r e d i b i l i t y of normal sources of information  can be destroyed  in a p o l i t i c i z e d situation.  When  t h i s happens, people w i l l pay more a t t e n t i o n to counterinformation  h i g h l i g h t i n g the r i s k s than t o r e a s s u r i n g  information  and w i l l demonstrate r i s k averse behaviour t o be on  the  "safe The  side." f i n a l p o i n t made i n t h i s a r t i c l e i s that  perception  risk  and r i s k a n a l y s i s are not the same t h i n g .  26 A number o f t h e p o i n t s made i n t h i s a r t i c l e a r e in assessing  the perception  F i r s t , people perception  of the  c a n n o t be e x p e c t e d  of the  flood hazard  in analyzing  accurate  1 i n 200  year  of the  range  is outside  the  of a w o r s t i m a g i n e d a c c i d e n t  flood hazard  i s q u i t e g o o d . The  something people l o t of p r o p e r t y imaginable  return of  is  important  because knowledge about the  flood  worst imagined f l o o d in Richmond i s  would r a t h e r not damage and  nuclear  f l o o d i s not thus,  Island.  experience.  Second, the use  hazard  on L u l u  t o h a v e an  because the  period used for f l o o d protection normal  flood hazard  important  l i v e through. It would cause a  d i s r u p t i o n . However, u n l i k e the  accident  l i k e l y to k i l l  something that people  or hazardous m a t e r i a l s  spill,  l a r g e numbers of people. are not extremely  worst a  A flood is,  a f r a i d of.  People  a r e e s p e c i a l l y a f r a i d of r i s k s t h a t a r e not w e l l known and could have c a t a s t r o p h i c  and  long l a s t i n g consequences.  i n R i c h m o n d i s a w e l l known h a z a r d , c a s u a l t i e s and  rather, perceive  also important. has  The  many b e n e f i t s  options  would l i k e l y cause  with  do n o t p e r c e i v e r i s k s and  few  for the people  risk directly,  benefits attached  d e c i s i o n t o l o c a t e an a c t i v i t y  f e r t i l e land, access water  Flooding  no l o n g t e r m e f f e c t s .  T h i r d , the point that people but  and  which  in Richmond  taking the r i s k , i n c l u d i n g  to a major metropolitan  area,  is  and  access  flat to  transportation. Finally,  i t should  Richmond does not Current  be n o t e d  that the  flood hazard  f i t the d e f i n i t i o n of a p e n d i n g  in  danger.  flood f o r e c a s t i n g systems give several days warning  that  27 a dangerously high  r i v e r l e v e l w i l l occur. In a d d i t i o n , 8 to  hours would elapse  a f t e r a dike break before  12  f l o o d i n g became  deep enough to immobilize road t r a n s p o r t a t i o n . T h i s summary of r i s k p e r c e p t i o n r i s k averse behaviour toward the  g i v e s no  i n d i c a t i o n that  f l o o d hazard i n Richmond can  be  expected.  Who S h a l l L i v e ? - V i c t o r F u c h s  (1974)  T h i s work analyzes the h e a l t h care States  system i n the  United  in the e a r l y 1970s from an economic point of view. I t i s  important to t h i s t h e s i s because i t i s one examples of a r i s k - b e n e f i t a n a l y s i s . The  of the  earliest  methodology used i n  t h i s work i s a p p l i c a b l e to r i s k a n a l y s i s , in g e n e r a l , control,  and  flood  in p a r t i c u l a r .  I t c o n s i s t s of the - I d e n t i f y i n g the  following  steps:  hazards.  - I d e n t i f y i n g a standard  which can  be used to judge  e f f e c t i v e n e s s of money spent to reduce the - Using economic a n a l y s i s to examine v a r i o u s will  not  increase  - Choosing the  the  hazard.  options  that  hazards.  l e a s t cost option  that does not  increase  the  hazards. The  problems i d e n t i f i e d  increasing costs, d i f f i c u l t y  in the U.S. i n access,  h e a l t h care and  mounting  system were health  problems. COST PROBLEMS T h i s work breaks cost problems in h e a l t h care cost problems and  i n t o average  unusual cost problems. Average c o s t problems  28 refer to the fact that the average  cost of health care i n the  U.S. i n c r e a s e d a t a g r e a t e r r a t e t h a n t h e r e s t o f t h e U.S. economy from  1963 t o 1972.  The u n u s u a l c o s t p r o b l e m s  a r i s e f o r a s m a l l number o f  p e o p l e who u s e l a r g e a m o u n t s o f m e d i c a l s e r v i c e s b e c a u s e major  of  illness.  ACCESS  PROBLEMS  Two t y p e s o f a c c e s s p r o b l e m s problems  and s p e c i a l access  General access problems  are identified: general  access  problems. occur with respect to primary  e m e r g e n c y c a r e , home c a r e , a n d c a r e o u t s i d e o f c u s t o m a r y  care, working  hours. These t y p e s of c a r e do not r e q u i r e t h e h i g h e r l e v e l s of skill  f o u n d i n m e d i c a l s p e c i a l i s t s . I n many c a s e s , t h e y c o u l d be  p r o v i d e d by p a r a - m e d i c a l general  s t a f f working  under  the guidance  of a  practitioner.  S p e c i a l access problems  a f f e c t s p e c i f i c groups  of people,  such as the poor, ghetto dwellers, and rural populations. HEALTH  PROBLEMS  This work.points  out concerns  that health levels are not as  h i g h i n t h e U.S. a s i n o t h e r d e v e l o p e d c o u n t r i e s a n d t h a t h e a l t h l e v e l s v a r y g r e a t l y among d i f f e r e n t g r o u p s . A d i s t u r b i n g t r e n d noted  i n t h i s work i s t h e d e c l i n e i n h e a l t h l e v e l s among  U.S.  males (with the exception of i n f a n t s and the very o l d ) between 1963 a n d 1972. HOW  IS HEALTH  JUDGED?  The m e a s u r e o f t h e g e n e r a l l e v e l o f h e a l t h used by work i s m o r t a l i t y . (The p e r c e n t a g e  this  of a population of a given  29 age  which can  be e x p e c t e d  argued that other m o r t a l i t y . An  to die before  It is  measures of h e a l t h are h i g h l y c o r r e l a t e d  with  i m p l i c i t assumption throughout the book i s that  changes to the h e a l t h care increase  a later age).  system which would lead to  i n m o r t a l i t y w o u l d n o t be a c c e p t a b l e .  c h a n g e s t h a t do not on t h e i r e c o n o m i c  l e a d t o an  increase  an  Conversely,  in m o r t a l i t y are  judged  merits.  ECONOMIC ANALYSIS The  t h r u s t of t h i s work i s t h a t m o r t a l i t y and  costs are  loosely  "The  c o n n e c t i o n between h e a l t h and medical c a r e i s not n e a r l y as d i r e c t as most d i s c u s s i o n s w o u l d h a v e us b e l i e v e . " ( F u c h s , 1 9 7 4 , p . 6) mortality  i n d i f f e r e n t age  examine the p o t e n t i a l * e f f e c t of i n c r e a s e d  f i r s t age  group discussed  notes t h a t most of the d e c l i n e occurred  nutrition,  medical  to  expenditures.  i s i n f a n t s -(0  to 1 years).  in infant mortality,  as a r e s u l t of h i g h e r  s h e l t e r , q u a l i t y of d r i n k i n g water, and  i n f a n t m o r t a l i t y has 1000  has  been very  i n t h e 2-month t o 12-month age that most i n f a n t deaths occur Reduction difficult.  g r o u p . I t has  improved  It i s suggested  (200-500  living  the m o r t a l i t y been so  between b i r t h and  of the d e a t h r a t e i n t h i s age  1800,  population,  This rise in  e f f e c t i v e in reducing  group has  It  As  dropped from-the very high rates  l i v e b i r t h s ) f o u n d i n 1800.  standards  since  l i v i n g standards.  s a n i t a t i o n have become a v a i l a b l e t o the g e n e r a l  per  groups  mortality  The  has  care  connected.  T h i s work d i s c u s s e s  Infant  health  rate  successful  1 month of proved  age. very  that the mother's n u t r i t i o n , smoking  30  h a b i t s , and age (very young or very o l d ) are more important than medical i n t e r v e n t i o n  in achieving further reductions in infant  mortality. Childhood The tremendous advances are  i n medical care s i n c e the 1930's  noted. These advances d r a s t i c a l l y  reduced the death r a t e ,  from c h i l d h o o d d i s e a s e s , through the use of drug and immunization t h e r a p i e s . Deaths relatively  r a r e and m o r t a l i t y  from c h i l d h o o d d i s e a s e s are i n c h i l d r e n between 1 and 15 i s  q u i t e low. There i s l i t t l e more that i n c r e a s e d medical expenditures c o u l d do to lower m o r t a l i t y  i n t h i s age group.  Young Adulthood For of  young American males,  3 out of 4 deaths occur by means  v i o l e n c e , i n c l u d i n g automobile and other a c c i d e n t s ,  suicide,  and homicide. B e h a v i o u r - r e l a t e d m o r t a l i t y such as t h i s cannot be reduced by medical c a r e . Early  Middle-Age For  of  male Americans  i n e a r l y middle age, the l e a d i n g causes  death c i t e d are heart d i s e a s e , cancer, a c c i d e n t s ,  c i r r h o s i s of the l i v e r ,  and homicide. L i f e s t y l e ,  e x e r c i s e , tobacco consumption,  suicide,  including  a l c o h o l consumption,  diet,  and the  p r o p e n s i t y f o r v i o l e n c e are the c h i e f c o n t r i b u t o r s to m o r t a l i t y for  t h i s age group. Again, i n c r e a s e d medical e x p e n d i t u r e s w i l l  not  s i g n i f i c a n t l y decrease the death r a t e i n t h i s age group.  Late  Middle-Age For  dominate  males i n l a t e middle-age, heart d i s e a s e and cancer as causes of m o r t a l i t y . As these d i s e a s e s are l i f e s t y l e  31 related,  i n c r e a s e d medical expenditures  w i l l not  significantly  decrease m o r t a l i t y . In summary, t h i s work presents mortality  in the U n i t e d  States  b a s i c l e v e l of h e a l t h care has of care  is relatively  considerable  been a t t a i n e d . T h i s b a s i c  level  a v a i l a b l e for most  w r i t t e n . T h i s f i n d i n g allows  scope to c o n s i d e r  a l t e r n a t i v e methods of  h e a l t h care that reduce cost and  increase  providing  access.  t h i s b a s i s the r a t i o n a l e f o r c u r r e n t  patterns  case that  i n v a r i a n t once a  i s f a r lower than the l e v e l s normally  Americans when the work was  On  a convincing  expenditure  i s examined. T h i s author s t a t e s :  "Although i t i s the p a t i e n t r a t h e r than the p h y s i c i a n who has the major i n f l u e n c e on h i s h e a l t h , the opposite i s t r u e regarding the cost of medical care."(Fuchs, 1974, p. 6) The  work goes on to p o i n t out  physician  i n determining  that the  importance of  h e a l t h c o s t s r e s u l t s from  the  the  p h y s i c i a n ' s c o n t r o l of medical procedures, h o s p i t a l i z a t i o n s , and drugs p r e s c r i b e d . The  suggestion  t h a t overpayment of  physicians,  because of t h e i r monopoly p o s i t i o n , i s a s i g n i f i c a n t cause of high h e a l t h care c o s t s i s r e j e c t e d . The more p h y s i c i a n s h e a l t h care  argument that  providing  i s a f e a s i b l e method of improving access  system i s examined. The  to  the  problems with t h i s approach  are the  i m p o s s i b i l i t y of t r a i n i n g s u f f i c i e n t p h y s i c i a n s  to  provide  a l l of the primary care access  high  cost of using h i g h l y t r a i n e d p h y s i c i a n s It  r e q u i r e d and  the  f o r t h i s purpose.  i s suggested that people want access  to the h e a l t h  system 24 hours per day,  7 days per week f o r primary  emergency c a r e . F u r t h e r ,  they want the person a t t e n d i n g  care  and them to  32  be  familiar  with  their  provision  of  f i l l  demand.  this By  health  more  highly  carefully care  options  Special  than access  The  is  made  health  However, the  it  system  care  is  patient  that, is  noted  and  leaves  problem  and  it  the  the  payment  excludes open  the to  the  costs  from  unusual  demands  for  also  noted  that  fee  service  payment  incentive  for  the  physician  to  the  the  way  to  to  the  less  expensive  problems  paying  fee  for  care  w i l l  poor  high  for  that  health  a  not  access  cost  cost  on  that  system.  of  how  is  with  unusual  matter  everyone  clear  clear  methods  desired,  that  is  s p e c i a l i s t s  made  with no  effectively  It  expanding  problems  conjunction  more  the  work  simply  in  if  trained  this  discussed point  history.  examining  system,  exist  case  for from  the  the  basis  health of  by  care  extremely  services.  provides  minimize  financed,  service  care  care.  higher.  p o s s i b i l i t y  health  health  is  be  were  It  i s  l i t t l e  usage  of  health  care. For fixed that  payment despite  economic are  these  in  value  reasons, per  the  person fact  nature,  from  is  that  major  judgements.  protection  universal  The  unusual  health  advocated. most  of  factors  the in  importance  financial  insurance  It  is  of  risks  in  this  equality are  on  a  to  note  work  is  interesting  analysis  making  based  this  recommendation of  both  access  and  value  judgements. Several of  health  include:  other  care,  recommendations  without  decentralized  adversely health  care  are  made  affecting delivery  to  reduce  health  the  care.  systems,  more  cost These  33  f l e x i b l e use supply  of h e a l t h r e s o u r c e s / p e r s o n n e l ,  with demand, and  matching  physician  matching h o s p i t a l c a p a c i t y with demand.  In summary, t h i s work found t h a t , beyond a f a i r l y l e v e l of a v a i l a b i l i t y of h e a l t h care h e a l t h care system on  s e r v i c e s , the e f f e c t of  improving o v e r a l l h e a l t h  Improvements in h e a l t h w i l l  and  l i k e l y come from medical research  and  system  system without endangering  Major d i f f e r e n c e s e x i s t between the  or  considerable  the c o s t s of the h e a l t h care  improving access to the  the  i s minimal.  from changes in human behaviour. I t a l s o found that scope e x i s t s f o r reducing  minimal  health.  f l o o d c o n t r o l problem  the h e a l t h care problem. In p a r t i c u l a r , the e f f e c t i v e n e s s of  the h e a l t h care deaths and  system can  be measured by average numbers of  average amounts of s i c k n e s s  r e s p e c t i v e l y ) . Because deaths and t h i s work d i d not consider  ( m o r t a l i t y and  i l l n e s s happen  morbidity  frequently,  the a d v i s a b i l i t y of p r o v i d i n g a  h e a l t h care system to handle i n f r e q u e n t  events that would a f f e c t  l a r g e numbers of people. In d e s i g n i n g  f l o o d c o n t r o l systems,  c a t a s t r o p h i c events must be c o n s i d e r e d . evaluate  infrequent, The  amount used to  f l o o d c o n t r o l p r o j e c t s , expected annual f l o o d damages,  w i l l probably never occur i n any  year.  Notwithstanding these d i f f e r e n c e s , the methodology presented in t h i s work i s extremely u s e f u l i n e v a l u a t i n g f l o o d hazard. T h i s work i s r e l e v a n t because i t presents of  i n t e g r a t i n g t a n g i b l e and  p o l i c y o p t i o n s . The  i n t a n g i b l e f a c t o r s to  the a method  evaluate  methods presented i n t h i s work are  a p p l i c a b l e to a wide range of problems i n c l u d i n g f l o o d c o n t r o l .  34 THE  FLOOD  L u l u I s l a n d i s 12000 h e c t a r e s province,  HAZARD  of f l a t  land i n a mountainous  l o c a t e d w i t h i n easy commuting d i s t a n c e of the downtown  of a major m e t r o p o l i t a n  area.  It i s , also, a low-lying  island  l o c a t e d i n the F r a s e r River e s t u a r y . L u l u I s l a n d i s made up of poorly consolidated  sandy s o i l s  i n the most t e c t o n i c a l l y a c t i v e  area of Canada. A l l of these f a c t o r s have l e d to the c r e a t i o n of a f l o o d hazard on L u l u Its  proximity  Island.  to the c i t y of Vancouver and f l a t  have c r e a t e d a s o c i a l and economic o p p o r t u n i t y . excellent  f o r the development of r e s i d e n t i a l ,  Flat  topography land i s  agricultural,  commercial and i n d u s t r i a l p r o p e r t i e s . The mountainous nature of B r i t i s h Columbia's topography and of the Vancouver area has meant the supply The  of f l a t  opportunity  l a n d f o r these purposes i s l i m i t e d .  to f u l f i l l  demands f o r f l a t  r e s i d e n t i a l , commercial, and l i g h t L u l u I s l a n d has been recognized In 1966, v i r t u a l l y was  land f o r  i n d u s t r i a l development on  f o r at l e a s t 20 y e a r s .  the whole western h a l f of L u l u I s l a n d  zoned f o r urban uses, d e s p i t e the f a c t that l a r g e p a r t s of  the urban zoned areas were i n a g r i c u l t u r a l use. The  opportunity  has been and i s being  r e a l i z e d by the  growth of an urban m u n i c i p a l i t y with a p o p u l a t i o n 100,000 and property  assessed  at $6 b i l l i o n .  grown by 2/3 s i n c e 1971 and i s s t i l l  of over  P o p u l a t i o n has  growing. R e s i d e n t i a l ,  commercial, and i n d u s t r i a l development have grown with the p o p u l a t i o n . The growth of commercial development has been e s p e c i a l l y notable  (see t a b l e I I I ) s i n c e 1971.  35 It  i s important  economic and  to keep i n mind the magnitude of the  s o c i a l o p p o r t u n i t y presented by the development of  L u l u I s l a n d i n e v a l u a t i n g the f l o o d hazard t h e r e . The p o s s i b i l i t y of p o t e n t i a l f l o o d damages, even extremely p o t e n t i a l f l o o d damages, has not been s u f f i c i e n t hesitation  large  to cause  any  in r e a l i z i n g t h i s opportunity.  The high l e v e l of development that has o c c u r r e d on L u l u I s l a n d i s a necessary p r e r e q u i s i t e  f o r a l a r g e f l o o d hazard to  e x i s t . I f L u l u I s l a n d were undeveloped,  no f l o o d hazard would  exist. Conversely, i f there i s development, but no p o s s i b i l i t y of f l o o d i n g , then there i s no f l o o d hazard. Two e x i s t around  sources of  flooding  L u l u I s l a n d : the S t r a i t of Georgia and the F r a s e r  R i v e r . To p r o t e c t a g a i n s t f l o o d i n g from these sources a of d i k e s has been b u i l t around  Lulu Island. Several possible  mechanisms e x i s t which c o u l d cause these d i k e s to f a i l result  i n subsequent  the s p r i n g  freshet,  damage to the d i k e s . C o n c e i v a b l y , combinations  these events c o u l d a l s o cause IV,  and  flooding.  These mechanisms i n c l u d e winter storms, and earthquake  system  of  f l o o d i n g , but as shown i n t a b l e  the p r o b a b i l i t i e s of combined events are s m a l l . To understand  the nature of these mechanisms and to  e v a l u a t e the s e r i o u s n e s s of a dike f a i l u r e caused by mechanism, a good understanding of the topography, expected  f l o o d depths, expected  f l o o d warning,  each  tidal  ranges,  and geology  on  L u l u I s l a n d i s necessary. In a d d i t i o n , an understanding of the  36  ease  of  repairing  mechanisms  is  a  dike  break  under  each  of  the  failure  necessary.  TOPOGRAPHY Lulu scale  used  (GSC). this  Island for  Zero  is  e s s e n t i a l l y  elevations  metres  GSC  discussion  a l l  Elevations  on  is  is  f l a t .  based  set  at  elevations  The  on  geodetic  mean  cited  standard  sea are  measurement  zero  l e v e l .  elevation  For  relative  the  to  rest  zero  of  metres  GSC.  length the  of  21  elevation  structures up  km.  to  at  Further,  on  Lulu  Even  Island  this  for  Lulu  must  least  .9m  almost  and  a l l  only  of  the  flood be  10% more  are  between  that  is  apt  description  A major the  major  break  implication  in  western  the  half  concentrated, TIDAL  an  dikes,  of  and  the  of  .9  of  anywhere  range  that  total  Lulu  over  area  So  it  a  overstates  has is  developed  2.1m.  f l a t  4.0m  purposes.  ground  the  and  this  island,  probably  narrow  heavily  areas  Om t o  control  on  of  residential "flat"  from  relatively  differences Island  vary  A l l been  built  above  2.1m.  commercial can  Island's  be  seen  topography.  topography  is  that  Lulu  Island,  where  most  urban  development  the  whole  i s l a n d .  flood  could  a  on  would  and  flood is  RANGES Tidal  levels  determinants  of  the  sun,  moon  and  are  tidal  inherently  variable  levels  the  are  atmospheric  phenomena.  gravitational  pressure,  and  wind  The  major  effects  speed  of  and  di rect ion. The and  low  gravitational tides  twice  a  effects day.  In  of  the  sun  addition,  and  the  moon  produce  gravitational  high pull  37 of the moon produces two  t i d a l c y c l e s per month (lunar day).  combined e f f e c t of s o l a r and single highest highest  lunar g r a v i t y u s u a l l y produces a  t i d e for each month and  t i d e f o r each year due  the h i g h e s t  normal  f o r each year.  to g r a v i t a t i o n a l  forces i s c a l l e d  i n v e r s e l y with atmospheric p r e s s u r e .  e f f e c t , the S t r a i t of Georgia i s a high pressure  a c t s as an  causes i n c r e a s e d water  of  Georgia,  a low pressure  system  levels.  High winds that l a s t  over a p e r i o d of s e v e r a l hours cause  l a r g e waves. T h i s wave set up adds to any r e s u l t i n g from changing atmospheric  t i d a l e f f e c t s or surge  pressure.  In p r a c t i c e , the h i g h e s t v e l o c i t y winds and atmospheric p r e s s u r e s  In  i n v e r s e barometer. When  system over the S t r a i t  water l e v e l s are depressed. Conversely,  occur  The  tide.  T i d e l e v e l s vary  there  The  occur  d u r i n g winter  lowest  storms. These storms  from November to March. Comparing Table V to the land e l e v a t i o n on L u l u I s l a n d , i t  can be seen that most of the  island  i s at e l e v a t i o n s equal  g r e a t e r than the normal high t i d e l e v e l . T h i s means that severe  t i d e surges d u r i n g winter  A l l of the  island  i s above low  storms present  tide  a flood  to or  only risk.  level.  CLIMATOLOGICAL CHANGE In recent years, there has  been i n c r e a s i n g s p e c u l a t i o n that  ocean l e v e l s are not s t a b l e . The  Atmospheric Environment  has  in sea  p r e d i c t e d a r i s e of up to 1m  level  i n the next  years, as a r e s u l t of a world-wide warming t r e n d . The this rise  i n sea  Service 50  r e s u l t s of  l e v e l would put most of L u l u I s l a n d below  38 normal above  high  tide  the.low  l e v e l ,  tide  but  would  FRASER  RIVER  STAGES  The  Fraser  River  only  freshet.  snowmelt  in  The  the  spring  number  of  during  the  spring  freshet.  -  The  amount  of  higher The  peak  spell  high The  Heavier  the  island  well  flood is  areas the  of  caused the  stage  These  hazard  during  by  the  Fraser  which  annual  River  w i l l  the  be  Basin.  A  reached  include:  occurring snowfall  during  the  produces  course  the  of  the  potential  for  a  runoff.  suddenness hot  -  snow  a  freshet  determine  winter.  -  poses  mountainous  factors  leave  l e v e l .  EXPECTED  spring  s t i l l  and  after  intensity a  cool  of  spring  spring  warming.  increases  the  A  sudden  chance  of  water.  geographical whole  basin  distribution  warms  of  spring  simultaneously,  warming.  higher  If  the  runoff  w i l l  result. -  The  co-ordination Fraser peaks  River from  reach  -  The  river 5600  occurrence  enough  8500  on  m  of  run-off of  discharge to  their  each  the  tributaries  peak  occur  other,  of  discharge. so  then  If  the flood  that  they  are  the  peak  reached  w i l l  higher.  peak If  which  tributaries  superimposed be  with  3  these  can / s .  be The  intense  from  that  coincides  with  snowmelt.  factors very  r a i n f a l l  occur  high.  highest  The  known  in  a  given  normal  peak  discharge  is  year,  the  peak  discharge 17,000  m  3  is / s .  A  39 discharge  g r e a t e r than or equal  t o t h i s one has a  p r o b a b i l i t y of b e i n g e x c e e d e d i n any  .005  one y e a r . A c c u r a t e  river  stages have not been c a l c u l a t e d f o r r i v e r d i s c h a r g e s higher  than  1 7 , 0 0 0 m^/s.  from  3.7m  River stages  for this discharge  s l o p e downward  a t t h e e a s t e r n e n d o f L u l u I s l a n d t o 2.5m  at the  western  end. At the lower .4 t o 1.6m  (western)  end of L u l u I s l a n d t h e s e  l e v e l s are  a b o v e 90% o f t h e i s l a n d . At t h e u p p e r ( e a s t e r n )  end  they are above v i r t u a l l y the whole i s l a n d . GEOLOGY L u l u I s l a n d i s l o c a t e d i n the area of g r e a t e s t t e c t o n i c activity  i n Canada. I t i s composed of l o o s e l y compacted  sands and .0021  sandy s i l t s . The  annual  p r o b a b i l i t y of  design earthquake  silty  a c c e l e r a t i o n has  occurrence.  When L u l u I s l a n d ' s s o i l s a r e d r y t h e y a r e s t a b l e u n d e r design earthquake  s o i l s are s a t u r a t e d . Under these c o n d i t i o n s , L u l u  occurs,  increased pore pressure  g r o u n d . The  e x p u l s i o n of sand and water can l e a d t o  settlement,  c a u s i n g c r a c k i n g i n f l a t areas and  criteria,  the differential  slumping  in  areas  s l o p e s . As t h e d i k e s f i t t h e s e  s i g n i f i c a n t damage to them would  A comparison  of  t h a t r e s u l t s when l i q u e f a c t i o n  l e a d s to the e x p u l s i o n of sand and water from  l o a d e d w i t h f i l l a n d on s t e e p e r  that  Island's  loosely consolidated s o i l s are l i k e l y to l i q u e f y to a depth The  the  a c c e l e r a t i o n . However, because L u l u I s l a n d i s  a l o w - l y i n g area, the water t a b l e i s always high, ensuring  6-9m.  a  of normal t i d e and  occur.  river l e v e l s with elevation  on L u l u I s l a n d s h o w s t h a t m o s t a r e a s o f t h e i s l a n d w o u l d be  at  40 or above high t i d e or r i v e r l e v e l s as long as the earthquake d i d not occur d u r i n g the s p r i n g f r e s h e t or an extreme high I t should be noted  that the p r e d i c t e d 1m r i s e  tide.  i n sea  level  from c l i m a t o l o g i c a l change a l t e r s t h i s s i t u a t i o n . Under the assumption of a 1m r i s e  i n sea l e v e l ,  t i d a l l e v e l s would be  higher than most of L u l u I s l a n d d u r i n g any high The  dikes surrounding  tide.  L u l u I s l a n d are made of the same  types of s o i l s as the r e s t of the i s l a n d . During the d i k e s are s a t u r a t e d and c o u l d be expected Greater damage c o u l d be expected than  extreme events,  to l i q u e f y .  to the dikes i f they,  rather  j u s t the u n d e r l y i n g s o i l s , are s a t u r a t e d . During  events,  r i v e r and  t i d e l e v e l s are higher than most of L u l u  I s l a n d . For both of these reasons, extremely  extreme  the combined event  (which i s  u n l i k e l y ) of earthquake and h i g h t i d e or h i g h  flows c o u l d produce severe  river  flooding.  DIKE REPAIR A key c o n s i d e r a t i o n i n a s s e s s i n g the s e r i o u s n e s s of any the f o r e g o i n g f l o o d hazards,  of  i s the ease with which a breach i n  the d i k e s can be r e p a i r e d . Many o r g a n i z a t i o n a l i s s u e s a f f e c t c a p a b i l i t y to r e p a i r d i k e s under emergency c o n d i t i o n s . At  the  this  p o i n t , adequate o r g a n i z a t i o n a l p r e p a r a t i o n s w i l l be assumed. Given adequate f l o o d f i g h t i n g c a p a b i l i t i e s , the most determinant  of the ease of dike r e p a i r  which water moves through  a  i s the v e l o c i t y  behind  dike repair  with  breach.  If the water i s moving very slowly all),  important  is relatively  straight  (or p r e f e r a b l y not at forward.  I f the area  the d i k e s i s dry enough that equipment can work i n the  41 breach, dike r e p a i r i s pouring through difficult The  i s even e a s i e r . On the other hand, i f water the d i k e at 2 m/s d i k e r e p a i r can be a very  task. e a s i e s t c o n d i t i o n s f o r the r e p a i r of d i k e s a r e those i n  which i t i s d r y behind the d i k e s and i n the d i k e breach. Under these c o n d i t i o n s , i t i s p o s s i b l e to work along the f u l l of  the breach  s i m u l t a n e o u s l y and any e a s i l y  length  accessible,  reasonably s u i t a b l e m a t e r i a l can be used to make the necessary r e p a i r s . Under these c o n d i t i o n s , access to s u f f i c i e n t of  quantities  sand and e a r t h moving equipment would be the l i m i t i n g  in e f f e c t i n g  r e p a i r s . Repairs made a f t e r an earthquake  factors  could  probably be made under these c o n d i t i o n s . Somewhat more d i f f i c u l t  c o n d i t i o n s occur when there i s  water i n the dike breach, but i t i s moving a t extremely low v e l o c i t y . Under these c o n d i t i o n s i t would not be p o s s i b l e to work behind the d i k e s because wet and/or muddy c o n d i t i o n s would prevent a c c e s s . Any reasonably s u i t a b l e m a t e r i a l c o u l d be used in  r e p a i r i n g the breach, but i t would be necessary  m a t e r i a l i n t o the dike breach  t o end dump  from on t o p of the dike a t e i t h e r  end of the breach. The l i m i t i n g  factor  i n making r e p a i r s would  be the l o g i s t i c s of maneouvering t r u c k s t o and from the ends of the d i k e breach along the t o p of the r e l a t i v e l y narrow d i k e s . Repairs made a f t e r a severe winter storm would probably r e q u i r e this  technique. The most d i f f i c u l t  c o n d i t i o n s occur when water  pours  through a breach at a p p r e c i a b l e v e l o c i t i e s . A breach d u r i n g the spring freshet could result  i n v e l o c i t i e s of 2 m/s. Water moving  42 at t h i s v e l o c i t y rock would  i s capable o f moving  5 cm d i a m e t e r  be d e s i r a b l e f o r r e p a i r work; a n d would  rock. Larger be n e c e s s a r y  for t h e f i n a l s t a g e s o f c l o s u r e . The ends o f t h e b r e a c h would u n s t a b l e a n d any s m a l l e r m a t e r i a l s (such a s sand) the breach would  be swept  dumped  be  into  away by t h e water p o u r i n g t h r o u g h t h e  breach. S e v e r a l s t r a t e g i e s have been  suggested to deal with  this  s i t u a t i o n . They i n c l u d e : - Catch the breach early before i t has a chance  to enlarge.  E n d dump r o c k i n t o t h e b r e a c h t o c l o s e i t . T h i s s t r a t e g y was s u c c e s s f u l l y a p p l i e d i n C h i l l i w a c k f o r a s m a l l breach i n 1948. Other breaches opened 100m  t o over  i n o n l y a few m i n u t e s d u r i n g t h e same f l o o d .  s t r a t e g y c a n o n l y be e x p e c t e d t o work f o r a  This  limited  number o f b r e a c h e s . - Build a ring dike around the breach. This approach  will  work a s l o n g t h e r e a r e n ' t m u l t i p l e b r e a c h e s . I t i s , however, slow because  because  i trequires several  t i m e s a s much d i k e t o be b u i l t a s t h e l e n g t h o f t h e b r e a c h . A c o n s i d e r a b l e amount o f f l o o d i n g c a n o c c u r while the ring dike i s being - L e t t h e water  built.  i n s i d e t h e d i k e s pond up t o t h e l e v e l o f  t h e r i v e r o u t s i d e o f t h e b r e a c h . When t h i s h a p p e n s t h e v e l o c i t y through the breach w i l l drop t o near zero and the b r e a c h c a n be d i r e c t l y r e p a i r e d . As f l o o d  damage  i s l a r g e l y d e t e r m i n e d by d e p t h o f f l o o d i n g , p o n d i n g on  43 Lulu  I s l a n d would  dikes  i n greater  damage t h a n  i f no  existed.  - D e l i b e r a t e l y breach the  result  island  the dikes  t o l e t t h e water d r a i n  a p p r o a c h would p r e v e n t strategy until  on t h e downstream e n d o f  level  This  p o n d i n g . The u s e o f t h i s  would p r o b a b l y  the r i v e r  o f f the i s l a n d .  mean t h a t  f l o o d i n g would  dropped c l o s e  last  to the bankful  level.  with  From t h e f o r e g o i n g  discussion,  water c o n t i n u o u s l y  flowing  i t i s c l e a r that  through  a breach  i t i s t h e most  difficult  type t o r e p a i r . TIDAL  RELIEF Implicit  concept  i n the foregoing  of t i d a l  relief.  in  t h e v e l o c i t y o f water  an  opportunity  conditions. hence, true  limit  that  provide  breach  great  isa  i s the  reduction  through a breach. This  provides  under much l e s s d i f f i c u l t  make d i k e  relief  opportunity  levels  i s welcome  r e p a i r much f a s t e r a n d ,  to level  with  tidal  Island. Tidal  enough t o f i t t h i s  relief  condition  is  low t i d e must  o r below t h e b o t t o m o f t h e  each t i d a l  relief  i t  i n a flood situation, to  to r e p a i r the dikes,  f o r s e v e r a l hours during  Island.  there  repair  t h e amount o f t h e r e s u l t i n g f l o o d i n g . W h i l e  a real  of L u l u  low t i d e ,  flowing  These c o n d i t i o n s  from F i g . 3, s i g n i f i c a n t half  During  to repair dikes  any t i d a l  reduce water  d i s c u s s i o n of dike  c y c l e . As c a n be seen  occurs  f o r the western  from t h e s p r i n g i n the eastern  freshet  i s not  h a l f of L u l u  44 It  i s reasonable to assume that a l l d i k e breaks on the  western h a l f of L u l u I s l a n d , from any source, can be r e p a i r e d in. under  24 hours. On the other hand, the l e a s t that c o u l d be  expected from a major dike break on the e a s t e r n end of the i s l a n d from the s p r i n g f r e s h e t  i s s e v e r a l days of f l o o d i n g .  FLOOD DEPTHS P r e d i c t e d f l o o d depths vary f o r the d i f f e r e n t  types of  hazard. The major determinants of f l o o d depth a r e the length of time to r e p a i r the d i k e s , the d i f f e r e n c e i n e l e v a t i o n between the of  water o u t s i d e the d i k e s and the ground  i n s i d e , and the s i z e  any d i k e breaches. The l e n g t h of time to r e p a i r a breach i s determined by the  s i z e of the breach and the techniques that can be a p p l i e d to effect  r e p a i r s . An extremely l a r g e breach would take longer t o  f i x because more m a t e r i a l would be r e q u i r e d . The techniques that c o u l d be a p p l i e d to repair, a breach depend mainly on the presence or absence  of t i d a l  r e l i e f . Without  tidal  relief,  water  i s c o n s t a n t l y moving a c r o s s a breach, making the task more difficult. The e l e v a t i o n d i f f e r e n c e a c r o s s a breach determines the v o l u m e t r i c flow r a t e through the breach. The e l e v a t i o n d i f f e r e n c e can be expected to be g r e a t e s t  f o r a breach on the  e a s t e r n end of L u l u I s l a n d . A breach from earthquake damage not a s s o c i a t e d with an extreme h y d r o l o g i c a l event would have a much smaller elevation  difference.  45 The width of a d i k e breach i s e s s e n t i a l l y random. One t h i n g i s c l e a r , a wider breach w i l l a l l o w more water  through than a  narrower one. The deepest f l o o d depths would r e s u l t e a s t e r n end of L u l u I s l a n d from which  from a breach on the  the water ponded to e i t h e r  the l e v e l of the i n f l o w water or the l e v e l of the d i k e s (whichever i s l o w e r ) . Expected f l o o d depths under  these  c o n d i t i o n s would be 2.3m. If no d i k e s e x i s t e d or d e l i b e r a t e breaches were made i n the d i k e s i n the western end of L u l u I s l a n d to prevent  ponding,  expected f l o o d depths would be 1.2m. I t should be noted that f o r a major breach i n the d i k e s i n e a s t e r n L u l u I s l a n d , a s i m i l a r l e n g t h breach would have to be opened downstream t o prevent ponding above the 1.2m  level.  F l o o d i n g from a winter storm c o u l d be expected t o i n c r e a s e by 6 cm per t i d a l c y c l e . As t h i s s o r t of f l o o d i n g would be s u b j e c t to t i d a l  relief  i t should be p o s s i b l e t o r e p a i r any  damage w i t h i n 24 hours. Damage from t h i s l e v e l of f l o o d i n g would probably remain w i t h i n a c c e p t a b l e bounds. F l o o d i n g from earthquake damage i n the absence extreme h y d r o l o g i c event would be l i m i t e d  of an  i n extent because most  of L u l u I s l a n d i s above normal h i g h t i d e . However, i f sea l e v e l r i s e s over the next 50 years due t o c l i m a t o l o g i c a l change, s e r i o u s f l o o d i n g would r e s u l t  i f r e p a i r s were not made q u i c k l y .  P o t e n t i a l damage from t h i s source i s not a s e r i o u s r i s k and may not m a t e r i a l i z e u n l e s s the p r e d i c t e d r i s e f a c t , take p l a c e .  i n sea l e v e l does, i n  46 FLOOD WARNING Of  the various  types  of flooding, the spring freshet  only one f o r which accurate breach  occurs.  for t h i s type  i s the  w a r n i n g s c o u l d be i s s u e d b e f o r e  Approximately  four days warning c o u l d be  of f l o o d i n g . These warnings would only  a  expected  predict  high water l e v e l s and the danger of f l o o d i n g . They would  allow  s u f f i c i e n t time t o s e t up d i k e p a t r o l s , f l o o d f i g h t i n g crews, and  t o move some p r o p e r t y  a full  scale evacuation  to higher  would be o r d e r e d  From t h e d e s c r i p t i o n of t i d a l ample opportunity be n e c e s s a r y ) road  levels. I t i s doubtful on t h i s b a s i s .  flooding,  i t i s clear  would e x i s t t o evacuate Lulu Island  before  that  that  (should i t  f l o o d depths were s u f f i c i e n t t o c r i p p l e  transportation. Flooding  from the spring freshet  i n the eastern  end of Lulu  Island would almost c e r t a i n l y require the evacuation Island f o r a l l except would be l e s s than 400m b r e a c h , reached.  the smallest  of breaches.  of Lulu  Water  levels  .3m f o r 12 h o u r s a f t e r a 2 0 0 m b r e a c h .  only 8 hours would elapse  As evacuation  before  For a  t h e .3m l e v e l w a s  would be much more d i f f i c u l t a t f l o o d  d e p t h s a b o v e .3m, 8 t o 12 h o u r s p r o v i d e s time a v a i l a b l e f o r orderly evacuation.  an o u t s i d e  limit to the  Beyond t h i s time,  highway s y s t e m w o u l d be i m p a s s a b l e a n d e v a c u a t i o n  the  would have t o  be c a r r i e d o u t b y b o a t o r h e l i c o p t e r . R A T I N G OF F L O O D  HAZARDS  T h r e e mechanisms were i d e n t i f i e d which c o u l d cause t h e dikes  to f a i l : winter  storms, the spring freshet, and earthquake  damage. I t i s c l e a r from t h e f o r e g o i n g  discussion  that the depth  47 and d u r a t i o n of f l o o d i n g from  these mechanisms makes the  f r e s h e t the most s e r i o u s hazard. storms i s a serious hazard the d i k e s . F l o o d i n g concern  from earthquake hazard  winter  i s more a matter  sea l e v e l . I f sea  e a r t h q u a k e d a m a g e w o u l d be a h a z a r d  as f l o o d i n g from winter No  by  o n l y i f no e f f o r t s a r e made t o r e p a i r  than a danger at c u r r e n t  f l o o d i n g from order  Flooding caused  level  precludes  on t h e  low d e p t h  (1976).  By u p d a t i n g  estimated  at roughly  into account  these  f l o o d damage from  was  q u a l i t y houses, and  for  i n c r e a s e , f l o o d damage has  $500 m i l l i o n  (see Table VI)  in this estimate  been  Factors  include: the l a r g e taken  p l a c e on L u l u  Island  done, the trend toward b u i l d i n g b e t t e r the trend toward developing  basements. These  f l o o d damage. The  does not  s o c i a l upheaval  100,000 p o p u l a t i o n ,  include intangible  for over  r e p a i r s a r e made, i s d i f f i c u l t  be n e g l e c t e d  in determining  costs  of s h u t t i n g down a a month  d i s r u p t i n g the l i f e of that community f o r the next while  higher  estimate.  Finally, this estimate  community, of  notincrease  f a c t o r s c o u l d make t h e a c t u a l f l o o d damage c o n s i d e r a b l y the above  the  Storage  studies to account  in c o m m e r c i a l development t h a t has since the study  of  damage.  s t u d i e s w e r e d o n e on t h e  i n f l a t i o n and p o p u l a t i o n  from  same  of f l o o d i n g , however,  s p r i n g f r e s h e t as p a r t of the F r a s e r R i v e r Upstream  than  rises,  storms.  large scale economic  Extensive  taken  of  s t u d i e s have been done to d e t e r m i n e the economic c o s t  t i d a l b a s e d f l o o d i n g . The  Report  spring  and 6 months  to q u a n t i f y , but  flood protection  levels.  should  not  48  RISK ANALYSIS  In  AND  PERCEPTION  a d d i t i o n to knowledge of the extent of a hazard,  knowledge of the l i k e l i h o o d of occurrence i s necessary to judge what c o n s t i t u t e s an a p p r o p r i a t e response. The o v e r a l l to a hazard can be determined statistical  i n t u i t i v e l y or by the use of  m o d e l l i n g . I f the response to a hazard i s judged  intuitively, statistical  response  the process i s c a l l e d  risk perception. If  m o d e l l i n g i s combined with q u a n t i t a t i v e measures of  the extent of a hazard to determine an a p p r o p r i a t e response, the process i s c a l l e d  risk  analysis.  Both r i s k a n a l y s i s and r i s k p e r c e p t i o n can be used to determine  the a p p r o p r i a t e l e v e l of p r o t e c t i o n a g a i n s t f l o o d i n g  in B r i t i s h Columbia. q u e s t i o n "How  In essence, both methods t r y to answer the  safe i s safe enough?". There  guarantee that both methods w i l l The  i s , however, no  a r r i v e at the same answer.  judgement of what c o n s t i t u t e s an a p p r o p r i a t e l e v e l of  protection  i s a problem  that has no c a l c u l a b l e s o l u t i o n . A l l  c o s t s of f l o o d i n g are not e c o n o m i c a l l y q u a n t i f i a b l e . f o l l o w i n g d e s c r i p t i o n of the P e a r l R i v e r f l o o d Mississippi a  i n A p r i l of 1979  The  i n Jackson,  d e s c r i b e s the s o c i a l upheaval  from  flood. "As the f l o o d waters receded the dimensions of the r e s i d e n t i a l p r o p e r t y damage became apparent. F l o o d damages are p a r t i c u l a r l y d e p r e s s i n g . Not only have people s u f f e r e d l o s s e s , but they a l s o must endure an e x c r u c i a t i n g c l e a n up p r o c e s s . The house i s normally a mess. I t s m e l l s . The water may be contaminated. The e l e c t r i c i t y i s u s u a l l y damaged meaning one must t o i l in the dark. Snakes can be p r e s e n t . C h e r i s h e d f a m i l y belongings have to be d i s c a r d e d i n t o a growing t r a s h p i l e . " ( A n d e r s o n and Weinrobe, 1979, p. 5) More d e t a i l  i s p r o v i d e d on the next page.  49  "The  l o s s of f u r n i t u r e , f i x t u r e s , and p e r s o n a l b e l o n g i n g s produced the most t o r t u o u s l o s s e s . W a l l b o a r d and c a r p e t i n g a r e i m p e r s o n a l a n d c a n be r e p l a c e d . The l o s s of f a m i l y photographs, a f a v o r i t e t a b l e , the d i n i n g room s e t or p i a n o goes w e l l beyond the monetary v a l u e of t h e s e i t e m s . The p i l e s of t h e s e and o t h e r o b j e c t s t h a t a c c u m u l a t e d i n f r o n t o f d a m a g e d h o u s e s was o n e o f the sadder s i g h t s observed i n Jackson."(Anderson and W e i n r o b e , 1 9 7 9 , p . 6)  In a d d i t i o n , not a l l c o s t s of f l o o d p r o t e c t i o n a r e q u a n t i f i a b l e . In p a r t i c u l a r the e n v i r o n m e n t a l c o s t s of c o n t r o l measures are often q u i t e d i f f i c u l t  to  flood  determine.  I t h a s , a l s o , been made c l e a r o v e r t h e y e a r s t h a t n o t a l l d e c i s i o n s c o n c e r n i n g f l o o d c o n t r o l a r e made on a p u r e l y b a s i s . The e c o n o m i c s  of damming t h e F r a s e r a t L i l l o o e t  k i l o m e t e r s n o r t h e a s t of Vancouver) d e t a i l because  economic (250  were never c o n s i d e r e d i n  o f t h e n e g a t i v e i m p a c t s o f t h e dam  on t h e  salmon  fishery. RISK PERCEPTION Recent  r e s e a r c h i n t o r i s k p e r c e p t i o n h a s s h e d some l i g h t  on  an i m p o r t a n t component o f the d e t e r m i n a n t of a p p r o p r i a t e p r o t e c t i o n l e v e l s . The p e r c e p t i o n of r i s k i s i m p o r t a n t the i n t u i t i v e assessment  of a hazard i n f l u e n c e s both  because individual  and c o l l e c t i v e r e a c t i o n to r i s k . Behaviour with r e s p e c t to c a n be c l a s s i f i e d a s r i s k p r o n e ,  r i s k n e u t r a l , or r i s k  risk  averse.  ( S l o v i c e t . a l . , 1984). - R i s k p r o n e b e h a v i o u r w o u l d p a y more t o a v o i d many s m a l l a c c i d e n t s t h a n t o a v o i d one amount of damage.  l a r g e one c a u s i n g t h e same  50 - Risk n e u t r a l behaviour would pay the same amount to a v o i d many small a c c i d e n t s as t o a v o i d one l a r g e one c a u s i n g the same amount of damage. - Risk averse behaviour would pay more to a v o i d one l a r g e a c c i d e n t than many small a c c i d e n t s c a u s i n g the same amount of damage.* Research determine of  i n t o r i s k p e r c e p t i o n has shown that  their  people  response to r i s k based on a number of q u a l i t i e s  the r i s k . These q u a l i t i e s  have been r e s o l v e d i n t o two  f a c t o r s : dread r i s k and unknown r i s k as shown i n F i g . 2. F l o o d r i s k has been drawn onto F i g . 2 as an open c i r c l e based on the fact  that the same technology i s used t o p r e d i c t dam f a i l u r e s as  dike f a i l u r e s , but dam f a i l u r e s are more s e r i o u s hazards. Dam failures  i n v o l v e deeper water moving a t much higher  velocities,  and c a r r y i n g l a r g e r d e b r i s . For these reasons dam f a i l u r e s are more l i k e l y  t o cause f a t a l i t i e s than the slow r i s i n g  waters t y p i c a l  flood  of the F r a s e r R i v e r .  The p o s i t i o n of the f l o o d hazard i n the lower l e f t  quadrant  of F i g . 2 l e a d s t o the h y p o t h e s i s , based on r i s k p e r c e p t i o n , that response t o the f l o o d hazard i s r i s k  prone.  * I t should be noted that t h i s d e f i n i t i o n of r i s k averse behaviour d i f f e r s from the d e f i n i t i o n of r i s k averse behaviour put forward i n Book and P r i n c i c d u r i n g the F r a s e r R i v e r Upstream Storage Report. In that work, r i s k averse behaviour was d e f i n e d as the d i r e c t i o n of more resources toward a v o i d i n g a hazard than the optimum l e v e l of e x p e n d i t u r e s d e r i v e d from cost b e n e f i t a n a l y s i s u s i n g expected c o s t s and b e n e f i t s would warrant. T h i s i s s i m i l a r to the c o n v e n t i o n a l d e f i n i t i o n from d e c i s i o n t h e o r y . P r a c t i c a l problems occur with t h i s l a t t e r d e f i n i t i o n because i t i s impossible to separate unmeasured i n t a n g i b l e s from the amount that can be a s s i g n e d to r i s k a v e r s i o n .  51 The  current  f l o o d c o n t r o l p o l i c y was n o t j u s t i f i e d on  e c o n o m i c g r o u n d s . T h i s f a c t was r e c o g n i z e d analysis of the flood hazard "The  The  on L u l u  in the last  economic  Island:  m o s t common p r a c t i c e i s t o b u i l d a s t r u c t u r e s o a s t o p r o t e c t a g a i n s t some l a r g e " d e s i g n " f l o o d d e t e r m i n e d more by p o l i t i c a l d e c r e e o r a r b i t r a r y s e l e c t i o n than by a n y s t a t e d e c o n o m i c a l l y r a t i o n a l c r i t e r i o n . " ( B o o k a n d P r i n c i c , 1975, p . 5) design  f l o o d f o r a l l f l o o d p r o t e c t i o n works i n B r i t i s h  C o l u m b i a i s a f l o o d t h a t h a s a .005 a n n u a l p r o b a b i l i t y o f occurring. This  f l o o d i s a l s o r e f e r r e d t o a s t h e 1 i n 200  year  flood. S e t t i n g a l l h a z a r d s t o t h e same p r o b a b i l i t y o f i s , however, a r i s k prone strategy.  The l e v e l of p r o t e c t i o n f o r  b o t h L u l u I s l a n d a n d Dewdney D i k i n g A r e a , area  80 k i l o m e t e r s  protection  a small a g r i c u l t u r a l  e a s t o f V a n c o u v e r , h a s b e e n s e t t o t h e same  l e v e l . Dewdney D i k i n g Area, is a smaller  flood hazard  a small and l i g h t l y populated than  i s t h e same f o r t h e two a r e a s ,  Dewdney D i k i n g Area,  than  area,  Lulu Island. Because the l e v e l of more i s spent  e a c h d o l l a r o f f l o o d damage f o r t h e s m a l l e r  hazard  f o r the larger hazard,  to avoid  in the Lulu  Thus i t c a n be seen that t h i s method o f determining protection  occurrence  Island.  levels of  i s r i s k prone.  Presently,  the expected  f l o o d damage f o r L u l u I s l a n d ,  after  a l l o w a n c e h a s b e e n made f o r t h e p r o t e c t i o n a f f o r d e d b y t h e dikes, refused  i s $15 m i l l i o n a n n u a l l y  (see Appendix C ) . Funding  was  f o r Westham I s l a n d under t h e f e d e r a l p r o v i n c i a l c o s t  sharing program because p r o t e c t i o n would not have been  cost  52 j u s t i f i e d at the s e t t i n g the The  1 i n 200  l e v e l of p r o t e c t i o n  gap  and  in  i s necessary.  between the c u r r e n t  c o l l e c t i v e r i s k preception Lulu Island  year l e v e l . * More f l e x i b i l i t y  l e v e l of p r o t e c t i o n , based  the expected c o s t s of  on  flooding  i s p a r t i c u l a r l y s e r i o u s . I t should be e s p e c i a l l y  worrisome to the p r o v i n c i a l cost  f e d e r a l government because the sharing  federal-  formula f o r f l o o d damage a l l o c a t e s  of the c o s t s of f l o o d damage in B r i t i s h Columbia over m i l l i o n to the  90%  $10  f e d e r a l government.  RISK ANALYSIS The  other methods suggested in the  literature  determining l e v e l s of p r o t e c t i o n are based on  for  risk  analysis.  They a r e : - Set  l e v e l s of p r o t e c t i o n to minimize the expected of f l o o d damage plus the c o s t s of f l o o d  costs  prevention  measures. - Use  a r u l e of thumb system to match f l o o d p r o t e c t i o n the  s i z e of the  f l o o d hazard.  S e t t i n g p r o t e c t i o n to minimize c o s t s  i s a v a r i a n t of  r i s k - b e n e f i t a n a l y s i s a p p l i e d to the p r o v i s i o n of h e a l t h s e r v i c e s . The  with  the care  a n a l y s i s a p p l i e d to h e a l t h care suggested ways to  minimize the c o s t s of p r o v i d i n g  h e a l t h care without  increasing  the expected number of deaths. A s i m i l a r method of s e t t i n g f l o o d p r o t e c t i o n l i m i t e d by  the  restriction  levels is also  that the chance of l o s s of l i f e  not  * The p r o v i n c i a l government has subsequently provided p r o t e c t i o n for Westham I s l a n d to a lower standard than the 1 in 200 year level.  53  be  increased  Lulu  Island  would  be  breach  in  this  the  p r a c t i c a l  time  dikes  to  protection exist  take  in  determining  costs  of  flood  to  in  into the  damage.  and  the  costs  of  social  are  d i f f i c u l t  to  measure.  the  expensive. and  residential  determine  protection.  The  analysis  a  more  dependent  final on  development 50  possible  flood  extra  flood  control  because  on  there  before  or  after  a  because  it  provides  this  intangibles. flood  them for  at  must  project  the  is  the done  and that  requirements a  major  costs  must  and  be  commercial done  levels  d i f f i c u l t  flood  and  considered,  more  be  great  d i f f i c u l t  varying be  can  i n d u s t r i a l ,  work  and  development  from  quantify  protection  control  both  of  resulting  required  that  be  works  that  floodproofing  Engineering  cases  damage  costs  or  some  Intangibles  protection  the  determine are  However,  method.  can  to  used.  to  of make  and  the  require  time. The  a  zoning  to  be  works  upheaval  surveys  of  island  environmental  properties.  costs  of  of  analysis  F i e l d  of  Similarly,  because  benefits,  severe  can  applying  control  occur  is  that  costs  doesn't  it  flood  attractive  account  The  flood  measure.  where  the  For  occurred.  of  constructing  very  evacuate  level  not  costs.  not  theoretically  does  Even  is  is  problems  d i f f i c u l t  minimize  limitation  exist  when  to  method  optimum  It  order  adequate  This an  in  year  problem  the in  this  assumptions  the  period  with  is  area an  to  be  made  approach about  the  protected.  inherently  is  inexact  that  it  course  Predicting process.  is  of  heavily future  growth  over  54  T h i s approach i s t h e o r e t i c a l l y o p t i m a l , smaller The  diking d i s t r i c t s ,  i s expensive and  r e s u l t s for a large diking d i s t r i c t  would be worthwhile and  probably  Another approach that has evaluation roughly  of dam  but,  e s p e c i a l l y for  cumbersome to  such as L u l u  Island  enlightening.  been widely a p p l i e d to  the  s a f e t y i s to use a r u l e of thumb system to  match the p r o t e c t i o n l e v e l to the hazard l e v e l .  example r u l e of thumb system has by the U n i t e d  apply.  been d e r i v e d  An  from the one  States Army Corps of Engineers, and  used  i s presented  in Table V I I I . There are  s e v e r a l disadvantages to the use  of a r u l e of  thumb c h a r t . I t does not attempt to i d e n t i f y an optimal p r o t e c t i o n and provide  i t does not  p r o t e c t i o n to given  l e v e l of  take i n t o account d i f f e r i n g c o s t s  to  level.  In terms of the second p o i n t , the c o s t s of f l o o d p r o t e c t i o n are a f f e c t e d by expected water l e v e l s , the shape and d i k i n g area,  and  s i z e of  the  the method used to achieve f l o o d p r o t e c t i o n .  C i r c u l a r d i k i n g areas are l e s s expensive per hectare than long, t h i n , banana-shaped d i k i n g areas.  The  enclosed  costs  of  b u i l d i n g dams f o r f l o o d p r o t e c t i o n have proven extremely high i n British  Columbia.  Notwithstanding these problems, t h i s method should dismissed  out  of hand. T h i s method p r o v i d e s  a better  not  f i t in  a s s i g n i n g p r o t e c t i o n l e v e l s to areas with d i f f e r e n t hazard l e v e l s than i s p r o v i d e d p r o t e c t i o n i n use  today.  by the s i n g l e province-wide l e v e l  of  be  55  It The  i s easy to implement from a p r o c e d u r a l  t a b l e f i t s on one  piece of paper and  can  p o i n t of view.  be  easily  memorized. Combined with p r o f e s s i o n a l judgement, i t can i n t a n g i b l e s and  f u t u r e growth p a t t e r n s  appropriate  and  j u s t i f i e d , economic modelling  engineering  design  The  take  i n t o account. Where and d e t a i l e d  could be used to a d j u s t these g u i d e l i n e s .  advantages of t h i s method are that i t i s easy to  implement and  allows  the f l e x i b i l i t y of p r o f e s s i o n a l judgement  to be a p p l i e d i n r e s o l v i n g i s s u e s i n v o l v i n g u n c e r t a i n t y difficulties  and  i n q u a n t i f i c a t i o n . I t cannot, however, be a p p l i e d  without t a k i n g the  i m p l i c i t c o s t base i n t o account.  From the f o r e g o i n g d i s c u s s i o n , each of the methods suggested has drawbacks. The strengths  f o l l o w i n g method draws on  of a l l three methods that have "been  the  discussed:  - A minimum l e v e l of p r o t e c t i o n be set f o r extremely hazard areas. An event with exceedence seems  .02  low  annual p r o b a b i l i t y of  reasonable.  - A r u l e of thumb c h a r t be used f o r a l l but d i k i n g areas or areas i n which there p r o b a b i l i t y of l o s s of  the l a r g e s t  is a clear  life.  - Formal r i s k b e n e f i t a n a l y s i s be done f o r the l a r g e s t areas and The  those i n which l o s s of l i f e  problems with the c u r r e n t method of s e t t i n g p r o t e c t i o n  l e v e l s for L u l u I s l a n d have i n c r e a s e d with development on L u l u I s l a n d . The development and Since  is a factor.  the amount of  expected damage i n c r e a s e s  decreases as l e v e l s of p r o t e c t i o n are  the l a s t upgrade to the d i k e s , development has  with  increased. increased  56 the f l o o d h a z a r d on L u l u I s l a n d , b u t p o l i t i c a l d e c r e e h a s h e l d the l e v e l o f p r o t e c t i o n , and hence  t h e r i s k , c o n s t a n t . The  r e s u l t has been  f l o o d damage. As  increased expected  development  on L u l u I s l a n d i s c o n t i n u i n g a n d t h e p o l i c y f o r d e t e r m i n i n g t h e l e v e l of p r o t e c t i o n has not changed, expected  t h e t r e n d w i l l be f o r  f l o o d damage t o c o n t i n u e t o i n c r e a s e . E v e n t u a l l y , i t  w i l l be n e c e s s a r y t o i n c r e a s e t h e l e v e l o f p r o t e c t i o n . ACCURACY OF HYDROLOGICAL Throughout  PREDICTIONS  this paper,  the statistical  predictions of the  p r o b a b i l i t i e s of h y d r o l o g i c a l e v e n t s have been  taken as a given.  For the Fraser River Basin, p r e d i c t i o n s of events with  annual  p r o b a b i l i t i e s a s low a s t h e d e s i g n s t a n d a r d o f .005 a r e reasonably well Attempts  supported.  t o p r e d i c t p r o b a b i l i t i e s of events t h a t happen  l e s s f r e q u e n t l y than the design events a r e l e s s w e l l The  supported.  lower t h e p r o b a b i l i t y of occurrence, the g r e a t e r the  u n c e r t a i n t y t h a t must be a t t a c h e d t o e s t i m a t e s o f t h e probability of occurrence. T h i s u n c e r t a i n t y comes from two s o u r c e s . F i r s t , of v a l u e s f r o m which a p r o b a b i l i t y d i s t r i b u t i o n  given a set  i s estimated,  o n l y one o f a w i d e r a n g e o f d i s t r i b u t i o n s c o u l d p l a u s i b l y be t h e c o r r e c t d i s t r i b u t i o n . Second, extremely  i t i s possible that events  with  low p r o b a b i l i t i e s o f o c c u r r e n c e do n o t f i t t h e  d i s t r i b u t i o n d e r i v e d from a v a i l a b l e data because by d i f f e r e n t p r o c e s s e s t h a n t h o s e t h a t c a u s e d  they are caused  known  events.  57  The  use of p r o b a b i l i t i e s with t h i s l e v e l of u n c e r t a i n t y i n  c o n j u n c t i o n with accurate c o s t estimates expected  t o produce a s i n g l e  f l o o d damage amount i s m e t h o d o l o g i c a l l y  unsound.  A second area of u n c e r t a i n t y i s the p r o b a b i l i t y that a d i k e will  fail  a t a given water l e v e l . I t i s unreasonable to expect  d i k e s t o be s a f e up to the design water l e v e l passes the design  as soon as the  level.  Whether a d i k e withstands above design  l e v e l and f a i l  water l e v e l s below, up t o , or  l e v e l s depends on many f a c t o r s i n c l u d i n g f l o o d  d u r a t i o n , underseepage, p i p i n g , b o i l s , v e g e t a t i o n and animal burrows i n the d i k e , and the e f f e c t i v e n e s s of f l o o d e f f o r t s . From t h i s l i s t , important The extremely  determinant  the l e v e l of maintenance i s an  of dike  stability.  l e v e l of maintenance that a d i k e w i l l difficult  fighting  receive i s  to p r e d i c t before the d i k e i s b u i l t .  I n s t i t u t i n g a nominal higher  l e v e i - o f p r o t e c t i o n by r a i s i n g the  d i k e s w i l l do nothing to ensure adequate maintenance. I t i s ,  in  f a c t , p o s s i b l e that the maintenance of higher d i k e s w i l l be worse because f l o o d i n g w i l l be l e s s  frequent.  OTHER STRATEGIES The  above d i s c u s s i o n suggests  reduce the r i s k than  that other s t r a t e g i e s t o  r a i s i n g the d i k e s be pursued. The  s t r a t e g i e s that w i l l be proposed w i l l be aimed at reducing or p r o v i d i n g f o r the hazard The  first  r a t h e r than  reducing the r i s k  levels.  s t r a t e g y i n v o l v e s s e c t i o n i n g L u l u I s l a n d by  r a i s i n g key p a r t s of the road system above f l o o d l e v e l s . In many  58  ways t h i s suggestion will  be d i s c u s s e d i n the next The  on an  i s an adjunct of contingency  that f l o o d i n g w i l l  to set up a contingency  d e f r a y the c o s t s of such f l o o d i n g . In e f f e c t , t h i s insurance program and w i l l insurance.  and  chapter.  second s t r a t e g y i s to accept  i n f r e q u e n t b a s i s and  planning  occur  fund to is a  flood  be d i s c u s s e d i n the chapter on  flood  59 CONTINGENCY PLANNING AND OTHER MEASURES TO REDUCE DAMAGE  While much has been w r i t t e n about how t o prevent and how t o design d i k e s to prevent breaches almost a l l i n f o r m a t i o n on r e p a i r i n g  from  breaches  flooding  occurring,  i s contained i n  e n g i n e e r i n g l o r e . I t has always been assumed that a dike breach resulting  from the s p r i n g f r e s h e t would be i m p o s s i b l e to  c o n t a i n . For t h i s reason, e f f o r t s have always been d i r e c t e d toward  e n s u r i n g that no d i k e breaches occur. T h i s approach has  i t s drawbacks. Past experience has shown that techniques to reduce the f l o o d r i s k below c u r r e n t l e v e l s a r e expensive to implement and c o n f l i c t with other uses of the r i v e r b a s i n . In p a r t i c u l a r , these techniques c o n f l i c t with f i s h e r y and recreational  uses.  Some p o l i c i e s have been suggested that would d i m i n i s h the f l o o d hazard by l i m i t i n g development on the f l o o d p l a i n or d e s i g n i n g f l o o d p l a i n s t r u c t u r e s to r e s i s t  f l o o d i n g . These  p o l i c i e s have not been p a r t i c u l a r l y e f f e c t i v e  i n c o n t r o l l i n g the  f l o o d hazard. The o p p o r t u n i t y to develop L u l u I s l a n d as an urban community has f a r outweighed  any p r e s s u r e s t o l i m i t  development  to the low d e n s i t y a g r i c u l t u r a l and r e c r e a t i o n a l uses that would limit  the amount of p o t e n t i a l  f l o o d damage. D e s i g n i n g s t r u c t u r e s  to withstand f l o o d i n g has proved to be too expensive f o r widespread  acceptance.  A " s a f e - f a i l " p o l i c y that would allow some f l o o d i n g  without  causing c a t a s t r o p h i c l o s s e s and would be e c o n o m i c a l l y f e a s i b l e would be a t t r a c t i v e .  60 CURRENT  POLICY  Before review  suggesting  current  break  occurs.  earth  moving  breach a of  as  major the  FLOOD  kept  dike  is  dikes  freshet  or  over  flood flood  with  p r i o r i t y  other  of  materials  to it  would  after  to  a  dike  personnel, repair  is  the  recognized  require  that  evacuation  Island.  rock  and  several  Island.  hand  for from  flooding  dike  trucks  procure  give  on  repair  private  notice  to  Lulu  after  of  agreements  piles  accessible  existence to  damage  addition  Lulu  necessary  requisition  freshet  However,  on  for  less  based  of  is  the  materials  building  These dike  other  materials  suppliers  repair. dike  and  has  occurred.  can  be  are  should  have  At  least  some  so  could  be  of  used  EQUIPMENT  Equipment  that  stock  materials  FIGHTING  found  In  spring  flood  to  repair  it  MATERIALS  operate  municipality  is  possible.  repair.  material  FLOOD  and  the  p o l i c y ,  limiting  planning  population  s p e c i f i c  repair  as  from  FIGHTING  for  for  equipment,  entire  sufficient  to  Current  quickly  suppliers  this  planning  breach  No  " s a f e - f a i l "  contractors. were  there  any  to  demands  also  flood be  notice  has  been  For  a  needed.  several  days  notice  should  or  and  be  even  a  of  of  personnel.  fighting  good  taken  equipment  the this  Formal  municipal  practice.  the  it  were  equipment  suppliers  emergency would  be  short  from  than  Advantage  needed  equipment  On  available  would  danger.  requisitioned  by-law demands  61 EVACUATION  PLANNING  T o t a l e v a c u a t i o n o f L u l u I s l a n d c o u l d be a c c o m p l i s h e d 8 h o u r s . T h i s e s t i m a t e depends on t h e highway system open.  Modeling  would  t a k e 8-12 h o u r s  i n 6-  remaining  done i n the course of t h i s study suggests that i t f o r f l o o d l e v e l s t o r e a c h t h e .3m  f r o m a m o d e r a t e t o l a r g e d i k e b r e a c h . Low l y i n g a r e a s  level would  r e a c h t h i s l e v e l m o r e q u i c k l y t h a n h i g h e r a r e a s . A s ,3m o r 1 foot of water  would  make t h e r o a d s y s t e m  these  areas  T h e r e a r e no s p e c i a l p r o v i s i o n s t o keep a c c e s s r o u t e s  open.  s h o u l d be i d e n t i f i e d a n d e v a c u a t e d  impassable,  first.  A C C E S S TO L U L U I S L A N D  The G e o r g e M a s s e y T u n n e l would because  c o l l e c t water  very quickly  i t i s below the l e v e l of the i s l a n d . A l l b r i d g e s a r e  above f l o o d l e v e l s , but access roads a r e n o t . I t i s reasonable to expect t h a t t h e approaches rest of the road  would  s t a y open as long as the  system.  SUMMARY O F C U R R E N T  CONTINGENCY  The c u r r e n t a p p r o a c h  PLANS  shows a good p r a c t i c a l g r a s p o f t h e  s i t u a t i o n and i s c e r t a i n l y adequate  f o r t i d a l based f l o o d i n g .  F l o o d i n g from t h e s p r i n g f r e s h e t i s a more d i f f i c u l t  problem.  From t h e p r e v i o u s d i s c u s s i o n of dike r e p a i r techniques, i t s h o u l d be c l e a r t h a t f o r a l l b u t t h e s m a l l e s t o f b r e a c h e s ,  the  feasible techniques available are: build a ring dike, l e t the f l o o d waters pond before r e p a i r , or breach the downstream d i k e s to p r e v e n t ponding.  The o p t i o n t h a t would  effect dike repairs  the most q u i c k l y , b u i l d i n g a r i n g d i k e , would m i n i m u m o f 48 h o u r s t o c o m p l e t e .  probably take a  A f t e r 48 h o u r s o f f l o o d i n g ,  62 f l o o d l e v e l s c o u l d be 1.2 to 1.8m. Large amounts of p r o p e r t y damage would r e s u l t . I t i s c l e a r that c u r r e n t contingency p l a n s would not be p a r t i c u l a r l y e f f e c t i v e  i n reducing f l o o d damage  a f t e r a dike breach o c c u r r i n g d u r i n g the s p r i n g SUGGESTIONS FOR CONTINGENCY  freshet.  PLANNING  An o p t i o n , that has been a l l u d e d to but has never been pursued, c o n s i s t s of segmenting  the i s l a n d to prevent a s i n g l e  breach from c a u s i n g f l o o d i n g throughout the most f e a s i b l e way to approach  the i s l a n d . Probably,  segmentation  would be to r a i s e  p a r t s of the road system so that they are e f f e c t i v e l y out of the flood  plain. If designed c o r r e c t l y , t h i s approach c o u l d be e f f e c t i v e i n  c u t t i n g the r i s k of a c a t a s t r o p h i c  f l o o d . The p r o b a b i l i t y of  both the d i k e s and the r a i s e d p o r t i o n of the road system  failing  would be extremely s m a l l . The areas that would be f l o o d e d would be l i g h t l y populated and have a g r i c u l t u r a l development. By a l l o w i n g f l o o d waters t o pond a g a i n s t the r a i s e d roads, dike r e p a i r s c o u l d be made more q u i c k l y . I t would ensure access t o the i s l a n d was maintained, both f o r evacuation purposes and t o move f l o o d f i g h t i n g equipment and m a t e r i a l s . One alignment that appears promising i s shown i n F i g . 4. I f a d i k e breach o c c u r r e d west of the proposed alignment, relief  would be a v a i l a b l e to l i m i t  relatively  ponding  r e p a i r time. Development i s  l i g h t east of the alignment  breach there would cause r e l a t i v e l y  tidal  so that f l o o d i n g from a  l i t t l e damage. The r a p i d  that would occur i n t h i s case would make i t p o s s i b l e to  r e p a i r the d i k e s q u i c k l y .  63 The be noted  one disadvantage  of segmenting the i s l a n d that should  i s that segmetation  would make f l o o d i n g worse i n the  areas f l o o d e d . The preponderance of development on the western end of L u l u I s l a n d makes segmentation worse f l o o d i n g  a good t r a d e - o f f because  i n l i g h t l y populated areas would be more than  o f f s e t by p r o t e c t i o n of l a r g e amounts of urban development. OTHER  RECOMMENDATIONS In a d d i t i o n to r a i s i n g road l e v e l s on L u l u I s l a n d ,  p r o v i s i o n should be made to ensure  b r i d g e and tunnel access  routes remain p a s s a b l e . The entrances to the George Massey Tunnel  should be diked on both ends or the tunnel w i l l  fill  with  water. All The  b r i d g e s are above f l o o d l e v e l but access roads a r e not.  l e v e l of bridge access roads should be r a i s e d above f l o o d  l e v e l . E n s u r i n g access routes to the i s l a n d are p a s s a b l e  will  a i d i n evacuation and rescue o p e r a t i o n s and w i l l allow p e r s o n n e l , equipment, and m a t e r i a l to be brought f o r dike  onto the i s l a n d  repairs.  Another c o n s i d e r a t i o n i s to make p r o v i s i o n t o r a p i d l y c l o s e o f f any underpasses,  c u l v e r t s , or other h o l e s i n the r a i s e d  p o r t i o n s of the road system. F a i l u r e t o do t h i s would r e s u l t i n flooding  i n the developed  areas.  As evacuation times w i l l be t i g h t , the lowest areas be i d e n t i f i e d and evacuated  should  f i r s t . Low l y i n g p o r t i o n s of the  road system (below .3m g e o d e t i c ) should be i d e n t i f i e d t o ensure that they do not block any evacuation r o u t e s . People not i n v o l v e d i n f l o o d f i g h t i n g should be encouraged to leave L u l u  64 I s l a n d and to s t o r e t h e i r p o s s e s s i o n s above f l o o d l e v e l s when i t becomes apparent  that high f l o o d stages w i l l be  Care should be taken  reached.  that adequate s u p p l i e s of m a t e r i a l s be  s t o c k p i l e d and a c c e s s i b l e from the d i k e s . A l t e r n a t e s u p p l i e s of m a t e r i a l s should be l o c a t e d o f f L u l u I s l a n d as a back up. Formal agreements should be made with t r u c k i n g companies or a m u n i c i p a l by-law should be drawn up to ensure adequate equipment i s a v a i l a b l e f o r f l o o d On the whole, contingency  fighting.  p l a n n i n g i s adequate as long as  l a r g e amounts of f l o o d damage a r e a c c e p t a b l e from f l o o d i n g caused  by the s p r i n g f r e s h e t on an i n f r e q u e n t b a s i s . On the  other hand, r a i s i n g the l e v e l of s e l e c t e d p a r t s of the road system would be an e f f e c t i v e method of reducing t h i s hazard and should be c o n s i d e r e d .  65 FLOOD  At the present, Canada. S e v e r a l The  l a r g e but  INSURANCE  time f l o o d  insurance  i s not a v a i l a b l e i n  f a c t o r s make i t an a t t r a c t i v e  infrequent nature  idea at t h i s  of f l o o d c o s t s make some s o r t of  f i n a n c i a l p r o t e c t i o n worthwhile f o r a l l f l o o d p l a i n u s e r s . s e n i o r governments, both f e d e r a l and what amounts to f l o o d insurance  p r o v i n c i a l , already  The provide  in that damages have  t r a d i t i o n a l l y been compensated. The  l a r g e , and  damage from a major f l o o d represents t r a n s f e r from o u t s i d e of the  time.  growing, expected  a d e f e r r e d , but  real  income  f l o o d p l a i n to f l o o d p l a i n u s e r s .  c u r r e n t p o l i c i e s do not p r o v i d e  local o f f i c i a l s  M u n i c i p a l i t y of Richmond s u f f i c i e n t  i n the  feedback to make r a t i o n a l  d e c i s i o n s about what l e v e l s of p r o t e c t i o n to request, design measures are a p p r o p r i a t e  what  f o r .flood p l a i n s t r u c t u r e s , what  zoning measures are a p p r o p r i a t e , and expected damage should be l e f t  The  what r e s i d u a l amounts of  to be p a i d as f l o o d  insurance  premiums. THE  NEED FOR  FLOOD INSURANCE  A major f l o o d on L u l u I s l a n d would cause a great d e a l of damage. Repair 1/5  to 1/3  costs for a t y p i c a l  of the value of the r e s i d e n c e . A burden such as  would cause f i n a n c i a l h a r d s h i p . On n a t u r a l area insurance The  residence would range from  the s u r f a c e i t seems l i k e a  f o r the p r i v a t e insurance  to spread  this  i n d u s t r y to  sell  the r i s k of f l o o d i n g .  s i t u a t i o n , however, d i f f e r s  s i t u a t i o n . U s u a l l y insurance  from a normal  insurance  i s i s s u e d when i t can be  that only a small p r o p o r t i o n of those  covered  expected  w i l l c l a i m in any  66 one  year, but that  c l a i m s w i l l come i n c o n t i n u o u s l y . T h i s  enables the insurance company to o f f s e t a continuous stream of c l a i m s a g a i n s t a continuous stream of premiums. The  s i t u a t i o n with f l o o d  insurance i s that  f o r any given  r i v e r b a s i n , c l a i m s can be expected to come only r a r e l y . When there i s a f l o o d , however, everyone covered by the f l o o d insurance can be expected to c l a i m point  of view, f l o o d  at once. From the i n s u r e r s '  insurance spreads the r i s k over time, not  over a group of p o l i c y h o l d e r s at any one time. GOVERNMENT INVOLVEMENT IN FLOOD INSURANCE Because of the damages caused by f l o o d i n g involvement on the part p r o v i n c i a l and f e d e r a l  of the p r i v a t e  damages (See Table  insurance i n d u s t r y , the  governments have agreed to share the  c o s t s of f l o o d damages. For l a r g e c a p i t a ) the f e d e r a l  and the lack of  f l o o d damages (above $4 per  government pays 90% of e l i g i b l e  flood  VII).*  T h e r e f o r e i n the p r i m i t i v e  sense of s h a r i n g a r i s k among  many, the p r o v i n c i a l and f e d e r a l governments do p r o v i d e  flood  insurance.  * I t should be noted that there i s no l e g a l requirement f o r e i t h e r the f e d e r a l or p r o v i n c i a l governments t o pay f l o o d compensation and that not a l l types of damage are e l i g i b l e f o r compensation under the f e d e r a l p r o v i n c i a l f l o o d damage cost s h a r i n g formula. Normal p r a c t i c e i s to set up a board of i n q u i r y to determine whether f l o o d damages a r e e l i g i b l e f o r compensation and to set a d e d u c t i b l e amount. Notwithstanding these l i m i t a t i o n s on f l o o d compensation, the type and extent of p o t e n t i a l f l o o d damages on L u l u I s l a n d make the a p p r o v a l of compensation a near c e r t a i n t y .  67 OTHER FUNCTIONS OF INSURANCE Insurance i s not j u s t a p r i m i t i v e r i s k - s h a r i n g t o o l . I t also provides provides  feedback on how w e l l a hazard i s being  managed and  a powerful way of modifying behaviour toward a hazard.  It has been shown that r e s i d u a l expected f l o o d damages on L u l u I s l a n d i s $15 m i l l i o n per annum. Recent c o s t s of b u i l d i n g dikes  on Sea I s l a n d were estimated at about $1 m i l l i o n per  kilometer.  As L u l u I s l a n d has 56 k i l o m e t e r s  of d i k e s ,  i t is  c l e a r that some improvement i n p r o t e c t i o n l e v e l s c o u l d be justi f ied. T h i s discrepancy  between the expected damage, as c a l c u l a t e d  on economic c r i t e r i a , and c u r r e n t perception users.  represents  p o l i c y based on r i s k  an income t r a n s f e r to the f l o o d p l a i n  I f the whole burden of the r e s i d u a l excess value  damages was added to Richmond m u n i c i p a l approximately 2.5 m i l l s t o property above, i t would be economically by  of f l o o d  taxes i t would add  taxes. As was p o i n t e d out  efficient  to reduce t h i s burden  increasing structural flood protection. The  point  i s not, however, that the M u n i c i p a l i t y of  Richmond should that  information  their perception  be f o r c e d to upgrade s t r u c t u r a l p r o t e c t i o n , but should  be given  to the m u n i c i p a l i t y so that  of the c o s t s of expected f l o o d damage matches  the a c t u a l expected c o s t s . I t i s not f a i r pursued which c r e a t e higher economically  f o r p o l i c i e s to be  expected f l o o d damage than i s  j u s t i f i a b l e and to expect an income t r a n s f e r from  s o c i e t y to cover that damage.  68  IMPLEMENTATION OF FLOOD INSURANCE Because of the p o s s i b i l i t y of a c a t a s t r o p h i c f l o o d o c c u r r i n g before enough premiums have been c o l l e c t e d t o cover it,  f l o o d insurance would have t o be implemented as a government  program. Because c o s t s are averaged r i s k group, coverage segregated It  should be mandatory and premiums should be  from general revenues i n a s i n k i n g  i s suggested  m u n i c i p a l taxes based  fund.  that premiums be c o l l e c t e d as p a r t of on the assessed value of p r o p e r t y , type of  p r o p e r t y , l e v e l of f l o o d r i s k , resist  over time r a t h e r than over a  f l o o d i n g , and an i n i t i a l  s p e c i f i c design measures t o study to determine  expected  f l o o d damage. Tying premiums t o assessed value would p r o v i d e a deferent to i n a p p r o p r i a t e development. As the c h a r a c t e r of the f l o o d hazard may change over time the f l o o d damage"study should be repeated  periodically.  SUMMARY In summary, adoption of a f l o o d insurance p l a n along  these  l i n e s w i l l a l l o w d i k i n g d i s t i c t s t o make r a t i o n a l d e c i s i o n s about development, b u i l d i n g d e s i g n , and f l o o d p r o t e c t i o n l e v e l s to request. I t w i l l provide s e n i o r governments with i n f o r m a t i o n about the p r i o r i t y with which t o implement f l o o d  control  p r o j e c t s . I t w i l l make e x p l i c i t what subsidy, i f any, i s p r o v i d e d to f l o o d p l a i n u s e r s . F i n a l l y ,  i t will  provide  resources t o r e p a i r the massive amounts of f l o o d damage t h a t would occur  i f L u l u I s l a n d were f l o o d e d .  69 CONCLUSIONS In the course of t h i s t h e s i s , s e v e r a l c o n c l u s i o n s  were  reached. They a r e : - There i s an  i n c r e a s i n g f l o o d hazard on L u l u I s l a n d  because i t s l o c a t i o n and  topography make i t h i g h l y  d e s i r a b l e f o r development as an greater Vancouver Regional I s l a n d i s assessed - The  D i s t r i c t . Property  the  on  Lulu  billion.  three mechanisms that c o u l d cause f l o o d i n g , in order of s e r i o u s n e s s winter  - The  at $6  i n t e g r a l p a r t of  of the hazard, are the s p r i n g f r e s h e t ,  storms, and  earthquake damage to the  dikes.  p r o b a b i l i t y of c o i n c i d e n t a l occurrence of combined events i s too small to r e q u i r e c o n s i d e r a t i o n i n planning  f l o o d p r o t e c t i o n f o r L u l u I s l a n d at  current  p r o t e c t i o n l e v e l s . If f u t u r e p o l i c y d e c i s i o n s r a i s e p r o t e c t i o n l e v e l s s i g n i f i c a n t l y , c o n s i d e r a t i o n of combined r i s k s may - The  be  required.  c u r r e n t method of s e t t i n g l e v e l s of p r o t e c t i o n i s r i s k prone. I t spends more per d o l l a r of expected f l o o d damage to p r o t e c t a g a i n s t  small  f l o o d hazards  than f o r l a r g e f l o o d hazards. - Expected c o s t s of f l o o d i n g on L u l u I s l a n d can  be  expected  to i n c r e a s e as long as the c u r r e n t p o l i c y of a l e v e l of p r o t e c t i o n i s f o l l o w e d and Lulu Island - The  accuracy  development  fixed on  continues.  of p r e d i c t i o n of the s i z e of h y d r o l o g i c a l  events g r e a t e r  than the c u r r e n t design  events i s not  70 sufficient  to be used with confidence i n r i s k  benefit  analysis. - Current contingency p l a n s are adequate f o r storm  based  f l o o d i n g . However, these plans would not be e f f e c t i v e in reducing f l o o d damage should there be a breach  near  the e a s t e r n end of the i s l a n d d u r i n g the s p r i n g freshet. - An i m p l i c i t  income t r a n s f e r to f l o o d p l a i n users on L u l u  I s l a n d i s c u r r e n t l y t a k i n g p l a c e as a r e s u l t of the expected  f l o o d damage, r e s i d u a l , a f t e r c u r r e n t  p r o t e c t i o n l e v e l s a r e taken - While  the earthquake  hazard  into  account.  i s a danger that should not  be minimized,  i t should not cause s i g n i f i c a n t  if  damage to the d i k e s were r e p a i r e d  earthquake  flooding  quickly. - As the t o t a l pumping c a p a c i t y on L u l u I s l a n d i s 1 m i l l i o n U.S. g a l l o n s per minute or l e s s than pumping system would be of l i t t l e  100 m /s the 3  use i n pumping out  water from a d i k e breach. The pumps are there to maintain drainage and pump out water r e s u l t i n g r a i n with the d i k e s  intact.  from  71  RECOMMENDATIONS The  f o l l o w i n g recommendations f o l l o w from t h i s  - F l o o d r i s k l e v e l s should be s e t t o be roughly n e u t r a l . Methods of s e t t i n g of  risk levels  study: risk  include a rule  thumb hazard c h a r t and r i s k b e n e f i t a n a l y s i s .  - The o p t i o n of segmenting L u l u I s l a n d by r a i s i n g s e l e c t e d p a r t s of the road system should be c o n s i d e r e d as an e f f e c t i v e method f o r reducing the f l o o d hazard  from  the s p r i n g f r e s h e t . - A government sponsored  flood  insurance program that i s  mandatory should be s e t up t o defray the c o s t s of f l o o d compensation and t o encourage r a t i o n a l d e c i s i o n making about the f l o o d hazard.  Premiums should be s e t  based on assessed value and the l e v e l of r i s k of flooding. - The f l o o d hazard  on L u l u I s l a n d i s not s t a t i c . As long as  development c o n t i n u e s , p e r i o d i c review the hazard  of the s i z e of  should be undertaken t o ensure that the  r e s i d u a l expected  damage i s not e x c e s s i v e . A complete  f l o o d damage study should be undertaken once per decade. - R i s i n g sea l e v e l s w i l l n e c e s s i t a t e r a i s i n g the l e v e l of the sea d i k e s t o accomodate higher t i d e l e v e l s , but will  not change the c h a r a c t e r of the storm  f l o o d i n g hazard. They w i l l hazard  based  change the c h a r a c t e r of the  from earthquake damage to.the d i k e s because  f l o o d i n g would r e s u l t  from a normal h i g h t i d e . For  72  this  reason,  before  the  available  evidence  should  considered.  be  confirmed  the  dikes  regarding If  a  dikes  should  taken  to  are a  rise  rise be  rebuilt,  in  in  sea  sea  built  the  level  level  to  best  is  withstand  earthquakes. -  Action  should  access -  A  to  p r i o r i t y , to  Lulu should  perform  damaged  be  a  a i r .  most  a  areas.  As  way  would  be to  that  not  bridge  be  cut  earthquake  survey  time  would  feasible  would  severe  careful  transportation the  Island  ensure  of  the  be  and  during  occur, dikes  limited  disrupted  by  perform  this  an  tunnel a  flood.  should  to and  be  locate surface  earthquake,  survey  is  by  any  73 BIBLIOGRAPHY  A i r P o l l u t i o n C o n t r o l A s s o c i a t i o n . A v o i d i n g and Managing E n v i r o n m e n t a l Damage from M a j o r I n d u s t r i a l A c c i d e n t s : P r o c e e d i n g s of an I n t e r n a t i o n a l C o n f e r e n c e H e l d i n V a n c o u v e r , B.C. N o v e m b e r , 1985. A i r P o l l u t i o n C o n t r o l A s s o c i a t i o n . P i t t s b u r g h , 1985. A l g e r m i s s e n , S . T . a n d T. H a r d i n g s . T h e P u g e t S o u n d W a s h i n g t o n E a r t h q u a k e o f A p r i l 29, 1965: P r e l i m i n a r y S e i s m o l o g i c a l Report. U. S.Coast and G e o d e t i c Survey. R o c k e v i l l e , Maryland. 1965. A n d e r s o n , D a n R. a n d M a u r i c e W e i n r o b e . E f f e c t s o f a N a t u r a l D i s a s t e r on L o c a l M o r t g a g e M a r k e t s : The P e a r l F l o o d i n J a c k s o n , M i s s i s s i p p i - A p r i l , 1979. N a t u r a l H a z a r d Research S e r i e s I n s t i t u t e o f B e h a v i o u r a l S c i e n c e #6. U n i v e r s i t y o f Colorado. 1979. Beak C o n s u l t a n t s (K4350).Proposed Improvements to the Fraser R i v e r S h i p p i n g Channel: P r e l i m i n a r y Report f o r P u b l i c Works C a n a d a . V a n c o u v e r , B.C. 1979. B o o k , A. N . P r o b l e m s A r i s i n g F r o m F l o o d C o n t r o l B e n e f i t S t u d i e s . Environment Canada, P l a n n i n g D i v i s i o n , Water P l a n n i n g and Operations Branch. 1971. B o o k , A . N . a n d R. P r i n c i c . E s t i m a t i n g F l o o d D a m a g e s i n t h e F r a s e r River Basin. Environment Canada, Inland Waters D i r e c t o r a t e , Water P l a n n i n g and Management Branch. 1975. B. C. M i n i s t r y o f E n v i r o n m e n t , Program Committee Papers. Byrne,  R i v e r s Branch. Unpublished.  Liquefaction  P . M . a n d D. M . A n d e r s o n . E a r t h q u a k e D e s i g n i n R i c h m o n d , B.C. S o i l M e c h a n i c s S e r i e s No. 75, D e p a r t m e n t o f C i v i l E n g i n e e r i n g . The U n i v e r s i t y of B r i t i s h C o l u m b i a . V a n c o u v e r . 1 983.  C l a r k , E. M. L o w e r F r a s e r R i v e r D y k e S u r v e y : L i q u e f a c t i o n . Canada Department of N o r t h e r n A f f a i r s and N a t i o n a l R e s o u r c e s , W a t e r R e s o u r c e s B r a n c h . V a n c o u v e r , B.C. 1963. C l a r k , E . M. R e p o r t on F l o o d F r e q u e n c i e s , E l e v a t i o n s , a n d D u r a t i o n s i n t h e Sumas L a k e A r e a . E n v i r o n m e n t Canada, Engineering D i v i s i o n , Water Planning Branch. 1972. C o m m i t t e e on S a f e t y o f Dams. S a f e t y o f Dams: F l o o d Earthquake C r i t e r i a . N a t i o n a l Academy P r e s s . W a s h i n g t o n , D. C . 1985.  and  C r i p p e n and A s s o c i a t e s L t d . E s t i m a t e of C a p i t a l C o s t s , R i v e r S t o r a g e , S y s t e m 'E' P r o j e c t s . U n p u b l i s h e d .  Fraser 1971.  74  Crosson, Robert S. Earthquake Hazard Evaluation in the P a c i f i c N o r t h w e s t : Open F i l e Report. F i l e 81-965. U. S. Geological Survey. 1981. Deal,  Terrence E. and A l l a n A. Kennedy. Corporate Cultures: Rites and R i t u a l s of C o r p o r a t e L i f e . Addison-Wesley. Reading, Massachusetts. 1982.  Farley, A. L. Atlas of B r i t i s h Columbia. B r i t i s h Columbia Press. 1979. Finn,  Liam.  Behaviour  of  Earth  Dams  The  During  University  of  Earthquakes.  Commission I n t e r n a t i o n a l e des Grands Barrages. Congres des Grand Barrages. Istanbul. 1967. Finn,  L i a m , R. G. Capanella, S o i l Models. Department M e c h a n i c s S e r i e s No. 8, 1969.  Finn,  Liam and Byrne, Peter M. The L i q u e f a c t i o n Vedder Canal Dykes. Unpublished. 1970.  F l a v e l l , D. Fraser Inland  The  Neuvieme  and Y. A o k i . Seismic T e s t i n g of of C i v i l E n g i n e e r i n g , S o i l The U n i v e r s i t y of B r i t i s h Columbia.  of  the  R. and R. 0. L y o n s . P r o b a b l e Maximum F l o o d s f o r River at Hope and M i s s i o n . E n v i r o n m e n t Canada, Waters Directorate. 1973.  the  F l a v e l l , D. R. a n d L y o n s , R. 0 . Environment Canada, Inland  Potential  Compile and Extend Waters Directorate.  Flow Data. 1973.  Fraser River Board. F i n a l Report of the Fraser River B o a r d on F l o o d C o n t r o l and H y d r o e l e c t r i c Power in the F r a s e r River Basin. Fraser River Board. V i c t o r i a , B r i t i s h Columbia. 1 963. Fraser River Joint Advisory Board. Fraser River Review Report. Fraser River Joint Advisory B.C. 1976. CBA  Upstream Storage Board. V i c t o r i a .  Engineering Ltd. Fraser River Flood Control Project No. T o w n s h i p of Richmond. Survey C o n t r o l Monuments and Benchmarks. Unpublished. 1971.  Fraser River Flood Control Township of Richmond, Improvements. 1973.  1968 Agreement. Contract No. 1,  Fraser  Commission.  River  the Isfeld,  Joint  Lower E.  0.  Fraser  Navigation 1973.  Program  Fraser  Valley River  Studies.  Dykes.  Upstream  Department  Project No. Sea Dyke  Liquefaction  Unpublished. Storage of  -  3,  Problems  of  1970.  Review  Public  3  Works  Task  No.  Canada.  57  -  75  F i s c h o f f , B., S. L i c h t e n s t i e n , P. S l o v i c , S. L. Derby, Ralph Keeney. Acceptable Risk. Cambridge U n i v e r s i t y Press. Cambridge, Massachusetts. 1981. Fuchs, Victor R. Who S h a l l L i v e ? : Choice. B a s i c Books Inc. New Hay  and Company. Vancouver Dykes R e h a b i l i t a t i o n . E). 1985.  Hodgson, J . H. Englewood  Health, Economics York. 1974.  and  International Airport, Sea (For Transport Canada A i r ,  Earthquakes and E a r t h S t r u c t u r e s . C l i f f s , New J e r s e y . 1964.  L.  Social  Island TP 6335  Prentice-Hall,  H o u r s t o n , W. R . Serpentine-Nicomekl Proj. 10 S e a W a l l Mud B a y . Comments of D e p a r t m e n t of F i s h e r i e s a n d Unpublished. 1971.  Proposal Forestry.  Howard, Terry R. e d . S e i s m i c D e s i g n of Embankments and Caverns. P r o c e e d i n g s of a symposium s p o n s o r e d by t h e ASCE Geotechincal Engineering D i v i s i o n . American Society of C i v i l E n g i n e e r s . New Y o r k . 1983. Inland Waters Branch, Engineering Liquefaction Problems of the Unpublished. 1970. Inland Waters Analysis Islands.  Divsion, P a c i f i c Region. Vedder Canal Dykes.  Directorate, P a c i f i c and Yukon R e g i o n . Economic of Dyke Improvement f o r Westham and Reifel 1982.  Inspector of Dykes. Correspondence February 1970 to August 1985.  on E a r t h q u a k e Unpublished.  Studies  J o n e s , W. C . S t a b i l i t y of Dykes in Lower F r a s e r V a l l e y . . Department of Mines and Petroleum Resources. V i c t o r i a , B.C. 1963. Kanakami and Asoda. Damage t o G r o u n d a n d E a r t h S t r u c t u r e s by the Niigata Earthquake of June 16, 1964. S o i l s and Foundations. Vol. VI, No. 1, pp. 14-30. January, 1966. Luternauer, John L . , G e n e s i s of M o r p h o l o g i c a l Features on the Western Delta Front of the Fraser R i v e r , B r i t i s h Columbia Status of Knowledge. G e o l o g i c a l Survey of Canada, Paper 8010. 1980. Lyons, R. 0 . Fraser River Upstream Storage Study Floods for System E R e s e r v o i r s . Environment Waters Directorate. Vancouver, B.C. 1975.  Spillway Canada,  McBean,  A  Edward,  Analysis  of  Michael  F o r t i n ,  Residential  and  Flood  Jack Damage  Gorric.  Estimation  Design Inland  C r i t i c a l Curves.  76  Canadian Journal February, 1983. Midwest  Research  of  C i v i l  Institute.  Engineering.  Earthquake  Risk  V o l .  and  13,  No.  1.  Damage  Functions. An I n t e g r a t e d P r e p a r e d n e s s and P l a n n i n g Model A p p l i e d t o New M a d r i d . U. S. Department of Commerce National Technical Information Service. S p r i n g f i e l d , V i r g i n i a . 1979. Milliman, J o h n D. Sedimentation in the F r a s e r River and Its Estuary, Southwestern B r i t i s h Columbia, Canada. Geological S u r v e y of C a n a d a . V a n c o u v e r , Canada. 1979. Milne, W. G . L e t t e r to C. H. Maartman R e s u l t s of C h i l l i w a c k and Vedder Simulation. Unpublished.  of June 15, 1970: Canal Earthquake  Pavol, Peter. Canal and R i v e r Levees. P u b l i s h i n g Company. 1982.  Elsevier  with  S c i e n t i f i c  Plazak, David J . Flood Control Benefits Revisited. Journal of Water Resources P l a n n i n g and Management. American Society of C i v i l E n g i n e e r s Water Resources P l a n n i n g and Management D i v i s i o n . V o l . 112, No. 2. A p r i l , 1986. P r i n c i c , R. E c o n o m i c A n a l y s i s of F l o o d C o n t r o l M e a s u r e s on the Vedder River. Inland Waters Directorate, P a c i f i c and Yukon Region, Vancouver, B. C . 1977. Ripley, Klohn and Leonoff I n t e r n a t i o n a l L t d . Richmond Dykes Remedial Treatment for Fraser River Joint Program Committee. Unpublished. 1969. Ripley, Klohn and Leonoff I n t e r n a t i o n a l L t d . Vedder Preliminary Liquefaction Studies. Fraser River Program Committee. 1970.  Canal Joint  -  Dykes;  Seed,  H. B . a n d I. M. Idriss. Ground Motions and S o i l Liquefactions During Earthquakes. Earthquake Engineering Research Institute. Berkeley, C a l i f o r n i a . 1982.  Seed,  H. B. L a n d s l i d e s D u r i n g E a r t h q u a k e s Due t o S o i l L i q u e f a c t i o n . ASCE J o u r n a l of the Soil Mechanics Foundations D i v i s i o n . September, 1968.  Seed,  and  H. B. Turnaqain Heights Landslide, Anchorage, Alaska. J o u r n a l of the S o i l Mechanics and Foundation D i v i s i o n . ASCE. V o l . 93, No. 5. July, 1967. pp. 325-353.  Shepard,  F.  Delta. August,  P.  and  The  W.  H.  American  1962.  Mathews.  Sedimentation  Associations  of  of  Petroleum  Fraser  River  Geologists,  77  Shanks, Gordon Ross. The R o l e Management. UBC M a s t e r ' s  of Perception Thesis. 1972.  Slovic, Paul, Sarah Lichtenstein, the Societal Impact of F a t a l Vol. 30, pp. 464-475. 1984.  and Baruch Accidents.  in  Flood  Plain  F i s c h o f f . Management  Modeling Science,  S t a t i s t i c s Canada. Table 5 - P o p u l a t i o n by S e x , and Proportion of Males to Females, for Census Metropolitan Areas With Components. 1971-1985. S t a t i s t i c s C a n a d a . Time S e r i e s Indexes for Vancouver and S t a t i s t i c s Canada. Table Metropolitan Areas. Togashi,  Hiroshoyoshi.  10 - B u i l d i n g 1971-1985.  Study  on  C o u n t e r m e a s u r e s . D o c t o r of University, Sendai, Japan, Varzeliotes, A. Regime and Vancouver,  Retreival of Canada. Jan.  Tsunami  Consumer Price 22, 1986.  Permits  Run-up  Issued  in  and  Engineering Thesis, Tohoku 1976. (trans. 1981).  N. T. F r a s e r R i v e r Upstream S t o r a g e Study: River Sediment Studies. Inland Waters Directorate. B. C. 1974.  Wallis, D o u g l a s . G r o u n d S u r f a c e Movements Due t o Earthquakes. Master's Thesis, University of B r i t i s h C o l u m b i a . 1979. Western Canada H y d r a u l i c Laboratories Limited. F e a s i b i l i t y Study: Development of a F o r t y - F o o t D r a f t N a v i g a t i o n Channel New W e s t m i n i s t e r to Sandheads. F i n a l Report Hydraulic Model Studies for P u b l i c Works Canada A p r i l , 1977. 1977. Western Canada H y d r a u l i c Laboratories. Hydraulic and Related S t u d i e s and Review of E x i s t i n g O c e a n o g r a p h i c , H y d r a u l i c and G e o t e c h n i c a l I n f o r m a t i o n on S t u r g e o n B a n k s f o r B . C . Hydro and Power A u t h o r i t y . Unpublished. 1980. Yamada, G . Damage t o E a r t h S t r u c t u r e s and (Niigata Earthquake, J u n e 16, 1964). Vol. VI No. 1. J a n , 1966. pp. 1-13.  F o u n d a t i o n s by the S o i l s and F o u n d a t i o n s .  APPENDICES Appendix  A  -  Tables  Appendix  B  -  Figures  Appendix  C  -  Calculation  of  Expected  Flood  Damages  79  Appendix  A  -  Tables  Table I - Terms for C l a s s i f y i n g Hazard (Committee on S a f e t y of Dams, 1985, p. L o s s of L i f e  Potentials 130)  Category  (Extent  Low  None expected(no permanent structures f o r human habitation)  Minimal (undeveloped to occasional structures or agriculture)  Signi f icant  Few (no urban d e v e l o p m e n t s a n d no more than a small number of inhabitable structures)  Appreciable (notable agriculture, industry, or structures)  High  More than few casualt ies  Excessive(extensive community, industry, agriculture)  of  Development)  expected  Economic  T a b l e II - U. S . Army C o r p s E n g i n e e r s H y d r a u l i c Guidelines: Recommended S p i l l w a y D e s i g n Floods (Committee on S a f e t y of Dams, 1985, p. 132)  Loss  or  Evaluation  Hazard  Size  Low  Small Intermediate Large  50to 100-yr frequency 100-yr to 1/2 PMF 1/2 PMF t o PMF  Significant  Small Intermediate Large  100-yr to 1/2 PMF 1/2 PMF t o PMF PMF  High  Small Intermediate Large  1/2 PMF PMF  of  Dam  Spillway  PMF  Design  Flood  80  1^1 f  !  .g  u l l d i n q  Permits (Statistics Canada Table 10 - B u i l d i n g Metropolitan Areas, 1971-1985) Year 1 971 1972 1 973 1974 1975 1 976 1977 1 978 1 979 1980 1 981 1982 1 983 1 984 1985  Value  (OOP's)  532,318 IV  -—Annual  Freshet Winter  Purposes in  8,174 17,380 15,700 23,352 25,997 37,455 34,219 17,891 145,447 38,518 52,071 34,255 21,311 22,096 38,452  Total Table  for Commercial Permits Issued  Storm  Earthquake  Probabilities  of  Combined  Flood  Freshet  Winter Storm  Earthquake  .005  0.0  less  0.0  .005  .00014  less than .0083  .00014  .0021  •  than  Hazards  .00083  81  Table  V  - P r e d i c t e d Changes to T i d a l ( L e v e l s Given in Meters GSC) Current  Normal Mean  Low  tide  Levels  High  Design  Tide  Yearly  High  Minimum  Table 1971  VI  Tide  Tide  Dike  -  Height  Flood  Estimate  Residential Commercial Industrial Agricultural  by  -  Damage  and  1 .0  1 .0  2.0  2.7  3.7  2.2  3.2  3.0  4.0  (Book  and  Lulu  Island  P r i n c i c ,  1975)  Secondary 2,408 15,034  Total  114,666  Change in Consumer P r i c e Index (Statistics Canada, 1986) - High - Low Population  Growth  (Statistics  Canada.  Damage High Low  2.98 2.68 1.67  Table  5  -  Combined I n f l a t i o n / P o p u l a t i o n - High - Low  -  for  (000's) 61,831 17,905 8,888 5,661 561 2,378  Income L o s s e s Miscellaneous  Flood  .6  0.0  Estimate  Category  Levels -1  Crop Other  Industrial Transfer Costs  Predicted  -2.6  Tide  Normal  Levels  Population Factors 4.97 4.47  Estimates $570,646 51 3 , 1 9 9  etc.,1971  -1985)  82  Table  VII  Damage Less  -  per  Federal-Provincial Capita  than  $1  $1.00  to  $2.00  to  Above  $4.00  Federal  Flood Share  Damage  Cost  Sharing  Provincial  Share  0%  100%  2.00  50%  50%  4.00  75%  25%  90%  10%  Formula  83  Table  VIII  -  Flood  Hazard  Example  Rule  of  Thumb  Flood  Protection  Low  Medium  Depth  <  .3m  ,3m  Flood  Duration  <  1  1  Flood  Warning  >  48  >  Flood  Damage Low  Exposure  day hrs  High  to  1.4m  >  to  5  days  >  12  hrs  P o s s i b i l i t y  small  l i t t l e  Medium s i z e d communities. P a r t s of large communities where the risk are comparable in population to sized community. urban  some  with  Moderate  High  with  rural  Rural  Very  5  days  Potential  U n i n h a b i t e d or s t r i c t l y development.  Large l i f e .  1.4m  None  Low  High  Chart  C l a s s i f i c a t i o n  Flood  Very  Level  communities.  communities  of  loss  of  rural  or  parts at a medium  p o s s i b i l i t y  large  \  numbers  of  of  loss  l i v e s .  of  84  Table  VIII(cont.)  Hazard Very  Level  Low  -  Recommended  Levels  of  Flood  Protection  Description Very  low damage or  Level  potential  Low damage p o t e n t i a l and low depth, duration and warning Low  Protection  None  Low damage p o t e n t i a l , medium depth, duration, warning or M o d e r a t e damage p o t e n t i a l , low depth, low d u r a t i o n , medium warning  1/100  Moderate  M o d e r a t e damage p o t e n t i a l , depth, duration, warning  1/100 to 1/2 PMF  High  H i g h damage depth, high or  potential, medium duration, medium warning  low damage p o t e n t i a l , high warning Very  High  high  Moderate damage p o t e n t i a l , depth, high warning  depth, 1/2 high PMF  PMF t o PMF  85  Appendix  B  -  Figures L i s t  of  the  Western  of  1.  Map  End  2.  Risk-Hazard  Perception  3.  Map  of  F u l l  Tidal  4.  Raised  Road  Figures  of  the  Lower  Rating  Chart  Relief  Alignment  Zone  Fraser  Valley  PORK. • «*i *  ^ITIXLL'  r -\  * i . .  \ \-  i if ' 1 > " i , !  Figure I - WESTERN LOWER FRASER V A L L E Y - F L O O D A B L E  AREAS  FACTOR 2  •  •HerM«t M » f  m t f n«orMat<«* a) iaccMnaa;  •  • Clactrtcttr (MUtlan • DES a) Rltrvfaa Fartllljan  Mtritn*  OH TacMclaaj  «T  (Ml Tar Nairajrava) •  • Caaatiai Uuat • Irlculara.Uylwt  Dtafmtlc 1 lajn IWrai  •eraa**  •  *  • •tftieiati  Aattatatlc** Ma*  •  •  • FCS's  I I I I k l u * w r « l a>  I I I  I  I  laatf *a1«t  I  I  I  • NucleartaaaponsFallevl  • Satellite Crashes • DOT • Fa>iI) Faels • Cael tamag (aollvtten)  a> Vaccina*  I I  Mvcltar Reactar Acctaenti  • ura«a» •«•*«•  • Asanas lauUtta*  •ota U M f>  Cafrataa • Awn.  ' J I  a) Radiaacttr* haste  »:.«.S-T  t I  I I I I  I 1 I  I I I  • Auto [uuutt (CO)  (Dltease*  I  I  I t I I I • Ltt Star... t Transport  FACTOR 1  I I I I  f — I — I I I #  „ , „ j,,  I I te  „„„  I  -H  • Ceal ntatag (Disease)  »r*» • Treckrs  Lara* Saaa  • Skyscraper Firat •facial' aaiponi (twr)e)  •  enters tlactric IHr i feci (flrri)_ _ „ ,  • III S»1i«9» tac taanega) Electric H1r « Appl (Shock)* ticycles*  Motorcycles* Iriaoes* Ftreaorts*  • •  Unamaitrr Csmt Span raraoaitai • General Aviation  *Co«l Mining Accieents  • Hioh Construction • Rinreae Ccllfiioni Alcohol Acctoeats coa. A l a l i a . #  *A*te laciaa. 4<au Accieents  • MMam a) Dynaattc  Factor 2  COKTRXLAILE •OT DREAD K T B.OSAL CATASTROHIC eOMEOUEKCES KIT FATAL EQUITABLE IRDIV1DUAL LOU list TO FUTURE KXEUTIOKS EASILY REDUCtO RISK OECRSASIRS •DLuVIARY HCSR'T AFFECT FC  ROT OBSERVABLE iftotam TO TKOSE EXPOSES EFFECT DELATED REV t m ( I S O IHOOMK TO SCIERCC  s tmm TC THOSE EIFCSED EFFECT IMMEDIATE OLD RJSt 11 SU DOrX TO SCIERCE  •MOWTKIUAiLE OREAD ftOBAL CATASTROPHIC ORSEOUEICES FATAL ROT tOu;TABLE CATASTROPHIC MICt list TO FUTURE HHEUTIOXS ROT EAS1LT (EDUCED 11 SIC lRCSEASlUS WVOLU»TA«T AFFECTS ME  Factor 1  F i g u r e 2 - HAZARD LOCATIONS ON FACTORS I AND 2 DERIVED FROM T H E INTERRELATIONSHIPS AMONG 16 RISK CHARACTERISTICS. EACH FACTOR IS MADE UP OF A COMBINATION OF CHARACTER I S T I C S . A S IS INDICATED BY T H E LOWER DIAGRAM. ( F R O M SLOVIC et a l . , 1 9 8 4 )  Figure  3' R I C H M O N D - A R E A OF T I D A L  RELIEF.  Figure 4= RICHMOND - ROADS WHICH C O U L D BE RAISED TO S E G M E N T A R E A S U B J E C T TO F L O O D I N G .  90  Appendix  Damage C a l c u l a t i o n August 12, 1986 A s s u m e d R a t e o f Damage I n c r e a s e 0.04 Effective I n t e r e s t Rate 0.08  for  Flood  24  25  26  Damage (000's) of F l o o d i n g Growth Factor  $275,000 .005 Expected Damage  $500,000 .01  $510,000 .005 Present Value  1.0000 1.0400 1 .0816 1 .1249  8925000 9282000 9653280 10039411  1 .1699 1 .2167  10440988 10858627 11292972  Est.  C  Stage Flood  Probability Year 1 2 3 4 5 6 7 8 9 10 1 1 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32  -  Expected  at  Mission  Flood  (feet)  1.2653 1.3159 1.3686 1.4233 1.4802 1.53951.6010 1.6651 1 .7317 1.8009 1.8730 1.9479 2.0258 2.1068 2.1911 2.2788 2.3699 2.4647 2.5633 2.6658 2.7725 2.8834 2.9987 3.1187  Lulu  8925000 8594444 8276132 7969608 7674438 7390199 7116488 6852914 6599103 6354692 6119333  11744691 12214479 12703058 13211180 13739627  5892691 5674443 5464278 5261898 5067013 4879345 4698629 4524606 4357028 4195656 4040262 3890622 3746525 3607765 3474144 3345472 3221566 3102248 2987350 2876708  14289213 14860781 15455212 16073421 16716358 17385012 18080412 18803629 19555774 20338005 21151525 21997586 22877490 23792589 24744293 25734065 26763427 27833964 28947323 30105216 31309424 32561801 33864273 35218844 36627598 38092702  33 34 35 36 37  3.2434 3.3731 3.5081 3.6484 3.7943 3.9461 4.1039  38 39 40  4.2681 4.4388 4.6164  41 42  4.8010  42849109  4.9931  43  5.1928  44563073 46345596  Island  2770163 2667564 2568766 2473626 2382010 2293788 2208833 2127024 2048245 1972384  39616410 41201066  1899333 (cont  inued  1828988 next page)  91  Year 44 45 46 47 48 49 50 Cumulative Present Yearly Budget  Growth Factor  Expected Damage  Present Value  5.4005 5.6165 5.8412  48199420 50127397  1761247  6.0748  54217793 56386504  6.3178 6.5705 6.8333 Value  52132493  58641965 60987643  1696016 1633200 1572712 1514463 1458372 1404358 204461692 $15,475,262  92  Calculation Flood Flood  of  Expected  Damage E s t i m a t e s level at Mission  Flood from  Damages  Book  and P r i n c i c (1975) 24 25 (000's) (000's)  Damage E s t i m a t e s by Category Residential Commerc i a l Industr i a l A g r i c u l t u r a l crop A g r i c u l t u r a l other Primary Industrial Transfer costs Miscellaneous Damages  32647 881 4 5109 4228  Total Population Total  Growth  Adjusted  for  Factor Pop.  Low High  estimate estimate  Annual Probability of stage Prob. of F a i l u r e given stage Combined Prob. of Failure Expected Annual low high  Cost  in  1986  61831 17905 6946 5603  61831 17905 8888 5661  548 21 4 4 2207  404 1401 1 486 7365  14465  561 2378 2408 15034  61 4 5 4  111649  114666  1 .67  1 .67  102628  186453  191492  2.68 2.98  2.68 2.9'8  2.68 2.98  $275,044 $305,832  $499,696 $555,632  $513,199 $570,647  0.05 0.1 0.005  0.02  Growth  Inflation Factors low high  26 (000's)  0.5 0.01  1 .67  0.005 1 0.005  Dollars $11,504 $12,792  93  Formulas The  Used  in  Calculating  formulas  used  to  Expected  calculate  Flood  expected  Damage flood  damage  follows: Growth  Factor  =  (1  +  Rate  Damage  Y  e  a  r  Damage  =  (Flood Flood  Damage Damage  at at  24 25  feet feet  * *  Prob Prob  Flood Flood  at at  24 25  feet feet  + +  Flood  Damage  at  26  feet  *  Prob  Flood  at  26  feet  )  Value  =  (Expected  Factor  I n c r e a s e )  Expected  Present  Growth  of  *  Damage)*  (!/(1+Interest  rate)  <  Y  e  a  r  ~ >) 1  are  as  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0062936/manifest

Comment

Related Items