Flood Map Project: What are the
implications of outdated
flood maps in BC?
Silja Hund | Ebbwater Consulting
Tamsin Lyle P.Eng | Principal | Ebbwater Consulting
What is a Pet Project?
http://www.ebbwater.ca/wp/
pet-projects/
Floods are an important issue
$7-$10 Bn
Loss Estimate for Catastrophic Flooding in BC
(ICLR and SwissRE 2010)
Flood Disaster Occurrences in Canada 1900-2012
(Canadian Disaster Database)
Floodplain Maps
• Basic tool for flood
management decisions
• Return of Investment of
2:1*
* The Association of State Floodplain Managers. Flood Mapping for the
Nation: A Cost Analysis for the Nation’s Flood Map Inventory.; 2013:1-15.
Lillooet River Floodplain (1990), Canada British Columbia Floodplain Mapping
Agreement.
BC Flood Maps are old
Canada British Columbia Floodplain Mapping
Agreement:
Provincially Designated Floodplain Areas BC,
Publicly available data, Ministry of Forests,
Lands and Natural Resource Operations*
83 Floodplain Maps available
Years of Designation: 1976 – 1998
Median Age: 26 years old
*http://www.env.gov.bc.ca/wsd/data_searches/fpm/reports/
# of floodplain maps
BC Flood Maps by region
Data
Provincially Designated Floodplain Areas B.C.,
Publicly available data, MFLNRO*
18
16
14
12
10
8
6
4
2
0
Vancouver Island: 16
Lower Mainland: 13
Southern Interior: 17
Kootenay: 17
Cariboo: 3
Skeena: 10
Omineca Peace: 7
*http://www.env.gov.bc.ca/wsd/data_searches/fpm/reports/
How old is your map?
Data used for map:
Provincially Designated Floodplain Areas B.C.,
Publicly available data, MFLNRO*
National Floodplain Mapping Assessment:
2,656 km of rivers mapped in BC
Less than 50% of what needs to be mapped **
*http://www.env.gov.bc.ca/wsd/data_searches/fpm/reports/
** MMM Group, JFSA, Matrix Solutions Inc. National Floodplain Mapping Assessment Final Report.; 2014.
BC Floodplain Map Inventory Report (Oct 2015)
Prepared by BC Real Estate Association & C. Parsons
No floodplain
map (31%)
Map created or
updated outside
BC FMP* within
10 years (21%)
Map created or
updated outside
BC FMP* more
than 10 years ago
(11%)
Graphic from
BCREA
*BC FMP = BC Floodplain Mapping Program
Map created or
updated during
the period of the
BC FMP* (36%)
Report:
72 of 369 local governments & First Nation
bands in BC responded to survey
Length of Hydrometric Record
Hydrometric Record used for
Floodplain Maps
Hydrometric Record available,
but not used for Floodplain Maps
On average, 30 % of
hydrometric record is
not used
Data
Provincially Designated Floodplain
Areas B.C., MFLNRO (47 Design Briefs)
Water Survey Canada – Length of
record of hydrometric stations used in
floodplain mapping
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010 2012
Hydrologic record length matters for
developing flood return periods…
Floodplain Map in 1995
Lillooet River near Pemberton (WSC 08MG005)
1,662
cms
1,513
cms
Why does it matter if our maps are old?
1. Our climate is changing
•
Only 1 of all 83 designated BC
floodplain reports mentions
climate change
2. Our vulnerability is changing
3. Our rivers are changing
In the US, a 45% increase in spatial extent of the 100-Year
floodplains is projected by the year 2100 (NFIP 2014).
BC’s Population is growing
7,000
1. Our climate is changing
•
BC Population (in thousands)
6,000
5,000
Projected
Population Growth
4,000
Only 1 of all 83 designated BC
floodplain reports mentions
climate change
2. Our vulnerability is changing
3. Our rivers are changing
3,000
2,000
1,000
0
1971
1981
1991
2001
2011
2021
2031
2041
Data Source: BC Stats – British Columbia Population Projections (May 2015)
http://www.bcstats.gov.bc.ca/StatisticsBySubject/Demography/PopulationProjections.aspx
Current Population living in Floodplains
10% of BC’s population
(~ 424,000 people) live
on floodplains.
https://maxosburn.cartodb.com/viz/5615dd3e-4cea-11e5-a70c-0e018d66dc29/public_map
Lower Fraser River Floodplain
Total population living on Lower Fraser River
Floodplain: ~ 325,000 (20011 census)*
* Stats Canada
Take home points
• Our maps are old, if not ancient
• They should be updated (or at least checked) every 5
years*
• There are serious consequences for communities and
people living in the floodplain if maps are not up-to-date;
it makes flood planning decisions difficult
• There is good news on the horizon 
*FEMA recommendation and international best practice
References
• BC Stats – British Columbia Population Projections (May 2015)
http://www.bcstats.gov.bc.ca/StatisticsBySubject/Demography/PopulationProjections.aspx
Canadian Disaster Database
ICLR and SwissRE 2010
NFIP 2014
WSC
Canada British Columbia Floodplain Mapping Agreement:
Provincially Designated Floodplain Areas BC, Publicly available data, Ministry of Forests, Lands and
Natural Resource Operations*
*http://www.env.gov.bc.ca/wsd/data_searches/fpm/reports/
Flood Map Project: What are the
implications of outdated
flood maps in BC?
Silja Hund | Ebbwater Consulting
Tamsin Lyle P.Eng | Principal | Ebbwater Consulting