A man carries a bag of clothing before leaving his home as floodwaters from the Saint John River continue rising in Grand Lake, N.B. on Wednesday, May 2, 2018. (Darren Calabrese/THE CANADIAN PRESS)

How to mitigate the effects of flood damage from climate change


Report says “keep the wetlands”.

In recent years, the news has been full of stories of bigger and more violent storms, and massive rainfall and flooding.

Scientists consulted on this question generally concluded that while actual rainfall amounts in Canada have not varied much, when, where and how they, occur have.   Combined with other weather anomalies such as unexpected heat spells melting snowpack rapidly, this has led also in recent years to record floods.

In the past few years as warming atmosphere and water had affected air and ocean currents, this has also affected climate patterns and there have been many weather records broken around the world, including record droughts, floods, heat spells, storms of greater intensity, wild fires and to a lesser extent cold.

Many experts such as  Xuebin Zhang, Senior Research Scientist Environment Canada agree that as the Earth warms it will increase extreme events, “As hot temperature extremes and extreme precipitation have increased globally, it is reasonable to expect the 100-year extreme hot temperature or 100-year extreme precipitation events to have become more frequent”

 Michael Mann, climate scientist at Penn State University in the U.S, has also stated ” What used to be, say, a 1,000 year event (like [Superstorm] Sandy or perhaps Harvey) is now, say, a 30 year event” and goes on to say, “We’ve loaded the dice through climate change so that these events are appearing far more often.”

Fire expert Mike Flannigan says wild fires across Canada have doubled since 1970 noting that, “My colleagues and I, attribute this to, and I can’t be any more clear on this, human-caused climate change”

Faced with rapidly increasing payouts from natural disasters due to climate change, the Insurance Bureau of Canada (IBC) commissioned a study on actions that might mitigate losses, primarily from flooding.

Blair Feltmate (PhD), is head of the Intact Centre on Climate Adaptation at the University of Waterloo, in Ontario, lead investigator for the study.


The Intact Centre and the International Institute for Sustainable Development collaborated on the study for the IBC. The Insurance Board says payouts by its members for natural disasters like floods, have more than doubled every five years since the 1980’s.

Blair Feltmate (PhD) Intact Centre on Climate Adaptation, U Waterloo (supplied)

As costs mount to deal with the huge financial burden and loss due to floods, governments in Canada are beginning to shift more financial burden onto insurers and to homeowners.

Flooding in New Brunswick in May this year.: Four cows had to be rescued from a flooded barn near the .Meduxnekeag River, just one of many rivers in the province that have risen over their banks (photo-courtesy Tammy MacLean)

Craig Stewart, Vice-President, Federal Affairs, IBC says. “Coastal and inland flood risk is rising across the country as a result of extreme weather events driven by climate change. Insurance companies are on the front lines of helping Canadians cope with the impacts of the changing climate, paying out over $1.5 billion in the last 12 months alone”.

In addition for every dollar paid by insurers, governments through taxpayers are paying three to four times that much.

May 2018: Flooding in the north of Rock Creek in the Boundary region of the B.C. Interior. Photo: Brady Strachan-CBC

Canada’s Auditor-General has reported that between the years 2009-2015, provincial and territorial governments have paid out disaster related compensation greater than the combined 39 previous fiscal years.

Similar damage and cost increases have also risen in countries all around the world.

The report says one of the most cost effective ways to limit property and infrastructure damage is to preserve environments such as wetlands, as they are.

May 8, 2017: Flooding of Pierrefonds, Qc near Montreal; The IBC says flood damage costs have risen dramatically in recent years due to climate change. (Paul Chiasson- CP)

“Natural infrastructure, such as an inland or coastal wetland, is not mere decoration – it limits flood risk and the downstream discharge of pollutants, while at the same time supporting biodiversity. In response, every attempt should be made to retain and restore natural infrastructure today, if we are to avoid unconscionable economic, social and environmental losses tomorrow.”  Dr. Blair Feltmate, Head, Intact Centre on Climate Adaptation

He says that in southern portions of Canada on average over 60 per cent of natural wetlands, ponds, marshes, streams, and creeks have been altered or removed.

Wetland such as this in the Rouge Valley near Toronto must be preserved in spite of heavy development pressure, in order to mitigate flood damage. It also helps to sequester CO2, and provide a haven for wildlife. (Rouge Valley)

The report indicates that maintaining this natural “infrastructure” could reduce flood damage during a major storm by 29 to 38 per cent.

Beyond the cost factor, the report notes that preserving such natural areas in or near cities is important for biodiversity, not to mention the added aesthetic benefits of keeping natural environments in those areas and creation of recreational opportunities.

The report says as much as possible, the natural infrastructure should be preserved as is, and where possible, landscape returned back to its natural state.

(*** this article has been modified to include citations from experts regarding the intensity and frequency of warming and extreme climate related events)

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5 comments on “How to mitigate the effects of flood damage from climate change
  1. Regarding 100-year storms, thank you for removing the previous statement “So-called “100 year events” are now occurring sometimes only a few years apart.” As CBC has acknowledged, there is no data to support that, and only the expectations of scientists. To see real data on 100-year storms intensities see Figures 2, 3 and 4 in my paper in the Journal of Water Management Modeling: https://www.chijournal.org/C449

    The trends are down since 1990. Less intense 100 year rainfall.

    CBC has acknowledged issues with insurance industry claims/statements on storm trends in the past, e.g., per Shawna Kelly, Managing Editor, CBC Windsor: “I have reviewed your concerns and agree that we should have confirmed through Environment Canada the claims made by Mr. Comisso and in an insurance industry newsletter that there are 20 times more storms occurring. We have since been in communication with Environment Canada, and have also reviewed the data you provided. Environment Canada verified that there has been no significant change in rainfall events over several decades.” – that was ins response to inaccurate reporting described here: https://www.cityfloodmap.com/2015/10/bogus-statements-on-storms-in-cbcnewsca.html

  2. Robert Muir says:

    Cost are important: “As costs mount to deal with the huge financial burden and loss due to floods, governments in Canada are beginning to shift more financial burden onto insurers and to homeowners.”

    The Ontario Society of Engineers has an interest in achieving solutions to flooding. It has flagged the issue of cost of green infrastructure to the Ontario government in comments on Bill 139 https://drive.google.com/open?id=1az42-2TZrcmRm2uHVcxG6mc3LBtb8vv-, in comments on Ontario Long Term Infrastructure Plan https://drive.google.com/open?id=1_ehoK0opvzeBFLv1Vrc6QFIbS9B5qFA8, in comments on Ontario`s draft Watershed Planning Guidance https://drive.google.com/open?id=1dNFzxZxlzxUx-g9DzvVHSvwceXhddkCq, and directly to the Intact Centre on Climate Adaptation as well (letter November 2, 2017) regarding cost-effective practices:

    It states: “Additional measures often cited for achieving flood resiliency include green infrastructure. Although effective at addressing water quality and erosion impacts of new development, green infrastructure comes with high lifecycle costs and is not considered an effective measure for achieving flood resiliency under severe rainfall. Emphasizing this point, our research indicates that green infrastructure may increase total lifecycle costs by several times over conventional servicing approaches.”

    Unfortunately, the natural infrastructure authors have not considered this input in the new report, and have failed to consider costs, or the burden that will be placed on communities. What’s worse, engineering input to the upcoming best practices report for existing communities is being excluded / rejected.

    The report disclaimer indicates that it is not professional advice. Conclusions ignore significant direct input from the engineering profession.

  3. Robert Muir says:

    Please fact check : “The report indicates that maintaining this natural “infrastructure” could reduce flood damage during a major storm by 29 to 38 per cent.”

    That % is based on the ICCA’s 2017 wetlands report and is not typical of any urban setting discussed in the interview, meaning that there are few if any easily deployed wetland flood mitigation solutions as suggested. The high percentages are attributed to the Laurel Creek subwatershed in Waterloo with i) atypical % of wetlands in a headwayer catchment, and ii) a river flood Special Policy Area downstream. That is 99.5% atypical of urban basement flooding and overland flooding areas, so no there is no readily available opportunity to add say 20% wetlands into all our neighbourhoods. Furthermore the % in the 2017 report was based on ONE storm and – Hurricane Hazel which is not what is causing today’s frequent claims and damages.

    And the City of Waterloo is not pursuing wetland flood mitigation to address their flooding Special Policy Area – so are the ICCA recommendations deployable? Neither Conservation Ontario, Ducks Unlimited nor Ontario Ministry of Natural Resources have any wetland flood mitigation projects ongoing – why? Because storing more flood water in wetlands disrupts the hydroperiods (wetting and drying periods) harming sensitive flora and fauna. In is impractical, environmentally harmful to modify wetlands and certainly not easily deployed as noted int the interview. Preserving what we have? Yes indeed we do that already.

    CBC, please dig below the surface on this topic. Dr Feltmate, given his biology background, may have an interest in preserving wetlands for various reasons and we can support environmental protection goals. But no municipalities are looking to wetlands to solve flooding issues.

  4. Robert Muir says:

    This is false based on Engineering Climate Datasets:
    So-called “100 year events” are now occurring sometimes only a few years apart.
    Data source?

    A Freedom of information request was sent to University of Waterloo this year to obtain data Dr Feltmate relies on for statements saying storms are bigger or more frequent (e.g, his Senate ctte presentation in March or TVO interview, and other numerous reports where he has indicated that there is “a lot of data” – no such data was available through the FOI. Here is the response letter from UofW:

    Dr Feltmate’s statement: “We’re experiencing storms of greater, more volume of water of rain coming down over short periods of time these days” confuses annual precipitation trends (that he often cites) with short duration intensities (volume over short durations). The report only suggests future changes (page 17), with no data on past 100 year storm trends.

    Ad Standards has help fix storm trend errors in insurance industry advertising like this: https://goo.gl/XiZL54

    Note the disclaimer in the IBC-ICCA-IISD natural infrastructure report:”This report has been prepared for general guidance on matters of interest/information purposes only and does not constitute professional advice. Do not act upon any information contained in this report without obtaining specific professional advice.” – I have reviewed the case studies in details and there are significant engineering gaps, most notably grey infrastructure reservoirs and underground tanks being (mis)classified as green/natural infrastructure – this contradicts the reports definitions on page 56.

    CBC needs to fact check like in this story: https://goo.gl/kXeNsH
    .. in response to my feedback.

    Robert Muir, P.Eng.

  5. Peter Ashcroft says:

    The changing living landscape must be respected at all times.
    Building site assessment must be upgraded.