Flood: Lessons learned from North American losses Alberta, Canada flood (June 2013)

Glenn McGillivray Managing Director Institute for Catastrophic Loss Reduction Toronto, Ontario, Canada 26 March 2015

ICLR

Mission - reduce loss of life and property caused

by severe weather and earthquakes

Created in 1997 by the Canadian non-life

insurance industry to confront rising disaster

losses

Multi-disciplinary research and education

provides an essential foundation for “science to

action”

Financed by member assessments (formula

based on premiums written), and flat-fee basis

for associate members

Historically, some funding through government

programs

Fee-based for specific research projects

Southern Alberta flood

June 19-24, 2013

50 to 150 mm of rain in 3 days

Small pockets of higher rainfall

‘Hybrid’ event (river and urban

flooding)

Evacuation of 100,000+

4 deaths

1000+ km of road damaged

In downtown Calgary alone 4000+

businesses and 3000+ structures

affected

CAD 1.7b insured (CHF 1.35b)

Approx CAD 6b economic damage

(CHF 4.75b)

Costliest insured natural catastrophe

in Canadian history

Source: Canadian Press

Lessons learned Riverine (fluvial) flooding

Riverine or fluvial floods occur when a river bursts

its banks, whether due to extreme rainfall, snowmelt,

ice jamming or any combination thereof.

Source: iStockphoto

Lesson 1

Pay attention to most recent lessons learned

Flood in Alberta in 2005

2006 Groeneveld committee report outlined many actions

to prevent a repeat

Resources for mapping and communicating flood risk

Call to stop selling government land in floodplains

Report wasn’t made public until 2012

Essentially none of the report recommendations were

implemented

Lesson 2

Eliminate flood damage to homes in the floodway, the

zone of highest risk of flooding

Prohibit new development in the floodway

Commit resources for structural investments in flood

defence

Consider land buy-out offers to relocate those in high risk

zones

Lesson 3

Strongly discourage rebuilding in floodways

Provide compensation to landowners to convert land in

floodways to recreational or other use

Owners that rebuild in the designated floodway should not

qualify for future government disaster assistance

Lesson 4

Revisit design flood criteria and establish a high

standard

British Columbia has a 200-year standard

Saskatchewan has a 500-year standard

Parts of Manitoba have 700-year flood protection from

defence structures

Alberta has 100-year flood criteria

Lesson 5

Actively communicate the danger of flood to homes in

or near the flood fringe

Recognize that flood proofing reduces the cost of

recovery from flooding but does not prevent the risk of

flood damage

Lesson 6

Consider requiring additional flood proofing actions for

homes located in areas at risk of flooding

Raise the lowest-floor elevation of buildings above the

flood elevation with an acceptable safety factor (i.e.

freeboard).

Very important when factoring in climate change

Prohibit basements where there is risk of flooding

Prohibit the use of basements for living space

Lessons learned Urban (pluvial) flooding

Urban or pluvial flooding is not directly associated with a

body of water and is largely caused by extreme rainfall

events.

Source: City of Ottawa

Lesson 7

Create a provincial urban flood damage reduction

strategy

The strategy should build on any existing guidance for

stormwater and sanitary sewage management

Should complement actions to reduce riverine flood

damage

Lesson 8

Develop a provincial strategy to upgrade sewer

infrastructure

Replace all combined sewer systems with independent

sanitary and storm sewers

Establish a timeframe for completion and clarify funding

options for local governments

Lesson 9

Consider increasing standards for sizing stormwater

pipes to focus on the 10-year-storm (not the 2 or 5 year

storm)

New standards should include a margin for uncertainty

about current and future precipitation for both the minor

system (i.e. underground pipes) and the major system

(i.e. overland flow routes)

This uncertainty is due, in part, to the impact of climate

change on frequency and severity of extreme rainfall

events

Lesson 10

Revise building codes to reduce the risk of urban flood

damage.

Codes should mandate the use of household mitigation

measures in new construction such as backflow

prevention devices

Ban use of reverse slope driveways etc

Lesson 11

Senior tiers of government should work with local

governments and other stakeholders - including the

(re)insurance industry - to promote actions that reduce

the risk of urban flooding for existing homes

May include bylaws, regulations and financial/insurance

incentives for homeowners to install risk mitigation

measures

Lesson 12

Major stakeholders, including local and senior levels of

government and (re)insurers do not always have

access to the information required to effectively manage

and reduce the risk of urban flooding

Senior tiers of government should require local

governments to create and disclose information about the

state and location of sewer/drainage systems and

overland flow routes

Senior government should work with local governments to

prepare and make available a property-by-property

database of actions implemented by homeowners that

affect or mitigate the risk of urban flooding

Alberta Auditor General report (6 March 2015)

Update flood hazard maps and mapping guidelines

Assess risk to support mitigation policies and spending

Designate flood hazard areas and complete floodway

development regulation

Assess effects of flood mitigation actions

Develop plan to regulate dams

Improve dam regulatory activities

Full report at http://www.oag.ab.ca/webfiles/reports/OAG%20March%202015

%20Report.pdf

Canadian catastrophes

10 killed/100 evacuated/community

assistance required/historically

significant/community unable to recover on

its own

Based on data from the Canadian Disaster Database, Public Safety Canada

Courtesy of Kim Sturgess, WaterSMART AB, 2014

June, 1929

“Keep people away from water, not water away

from people”

Additional reading Making flood insurable for

Canadian homeowners

(www.swissre.com or

www.iclr.org)

Best practices for

reducing the risk of future

damage to homes from

riverine and urban

flooding (www.iclr.org)

Flood Forecast

(www.amazon.com)

Cities adapt to

extreme

rainfall:

Celebrating

local

leadership

(www.iclr.org)

Thank you!

gmcgillivray@iclr.org

www.iclr.org

www.basementfloodreduction.com

Twitter: @iclrcanada