Storm Warts, The Floods Awaken, A New Hope for Cost-Effective Investment in Flood Management Infrastructure, #NWWC2018 Robert Muir

Storm Warts
Storm Warts are the blemishes in our infrastructure system
capacity that reduce resiliency and contribute to flood losses.
My presentation "Storm Warts, The Floods Awaken" at The National Conference of the Canadian Water and Wastewater Association, Montréal, Canada, on November 5, 2018 will have a light show, light saber show that is.

Click below for the print version of the slides (unfortunately without all the fancy animation and sounds):

The presentation identifies benefit cost analysis as a "New Hope" for guiding infrastructure investment, so that they deliver a high return on investment by focusing on the blemishes in storm and waterwater collection systems, aka, "Storm Warts".

The presentation reviews the statement in the media, put forth by the insurance industry and affiliated researchers, that water damages are increasing and are a key driver for increasing catastrophic losses. The presentation shares data that suggests floods have not "awakened", and are in fact becoming a smaller percentage of total catastrophic losses, as explored in a recent post.

The presentation also reviews case studies of benefit cost and economic analysis related to grey and green infrastructure, including natural infrastructure (green infrastructure, low impact development measures including wetlands and other features). This includes case studies from the recent Insurance Bureau of Canada report reviewed in another recent post. It is suggested that cost benefit studies require certain elements to be robust, reliable, and evidence-based, and that some case studies are lacking in these core requirements, representing "number stretching and concept massaging" as suggested in the Financial Post.

A comparison of return on investment, benefit cost ratios, for Markham's complete flood control program is made, including a group of low-cost, no-regrets best practices (i.e., policies and programs such as sanitary downspout disconnection, and backwater value and sump pump incentives), and city-wide grey infrastructure capital works resulting from a decade of master plans and Municipal Class EA studies.. The ROI of green infrastructure is also explored as part of a city-wide assessment, including an evaluation of potential flood mitigation benefits, as well as erosion mitigation and water quality improvements.

The need for comprehensive engineering analysis is suggested, showing that case studies that relied only on "meta-analysis", or high level estimation techniques, may not be able to provide reliable, meaningful ROI estimates sufficient to guide public infrastructure spending. Wetland, natural infrastructure benefit-cost ratio's are shown to be highly variable and potentially unreliable, as reviewed in an earlier post that incorporates some of the Storm Warts presentation (i.e., Pelly's Lake, Manitoba) and reviews other sources on natural infrastructure flood reduction potential and constraints.

Do Baseflow Impacts of Urbanization Warrant Green Infrastructure Retrofits to Restore Water Balance?

Green infrastructure, low impact development practices (LIDs), also called stormwater management best management practices (SWM BMPs), are often proposed to restore water balance functions and mitigate impacts or urbanization on runoff and recharge. One argument is that baseflows are lowered due to reduced infiltration and discharges to watercourses. It is a simple textbook theory.

What does the data show on baseflow impacts? The following slide presentation was prepared to respond to the Ontario draft LID guidance manual in early 2017 since water balance impacts have been cited as justification for green infrastructure LIDs.

Local studies show that baseflows have increased over decades of urbanization, calling into question the need for such measures considering that potential impact has not materialized. As noted in TRCA's Approved Updated Assessment Report under the Clean Water Act, at most gauges there was an upward trend in baseflows which prompted this statement: "These overall increases to baseflow volumes are contrary to the common thought that increased impervious cover leads to reduced baseflow" - so for those keeping score, data - one, common thought - zero. (see page 3-40 at link to full report - disregard old link in the slide deck thx!).

TMIG also analyzed baseflows in the GTA and noted “The seven-day average consecutive low flow data provides an indication of the observed baseflows within a watercourse, and hence is a suitable measure for determining whether baseflow trends exist in an urbanizing area. The trend analysis identified noticeable baseflow trends in 13 of the 24 recording stations. Of these eight urban and two rural stations exhibited an upward trend, suggesting increasing baseflow.” (link to full report).

It would appear that baseflow stresses due to urbanization, i.e., development within the GTA, do not support the need for green infrastructure implementation to restore water balance functions.

Are Water Damages Increasing in Canada? Insured Losses for Flood, Rain, Storm and Hurricane Perils Show Decreasing Trend

The Insurance Bureau of Canada, Intact Centre for Climate Adaptation and International Institute for Sustainable Development released a report on natural infrastructure for flood resiliency called "Combatting Canada’s Rising Flood Costs: Natural infrastructure is an underutilized option", available here.

The report states:

"The financial impacts of climate change and extreme weather events are being felt by a growing number of
homeowners and communities across Canada. The increase in P&C insurance losses is indicative of the growing costs associated with these events. These losses averaged $405 million per year between 1983 and 2008, and $1.8 billion between 2009 and 2017. Water damage is the key driver behind these growing costs."

A review of loss data suggests that water damage is not the key driver behind growing costs, represents less than a third of total losses and is decreasing slightly as a percentage of total losses. The following chart from the report shows total losses:

And this next chart shows the distribution of water damage peril losses up to 2008 and after 2008:

The values for the chart above are summarized in the following table:

Wetlands and Natural Infrastructure for Flood Mitigation - Ontario Feasibility Assessment Suggests Limited Potential - Studies Note Conflict Between Preserving Biodiversity and Flood Attenuation

Wetlands, or natural infrastructure, for flood mitigation has been promoted by the Intact Centre on Climate Adaptation (ICCA) in their report 2017 report "When the Big Storms Hit: The Role of Wetlands to Limit Urban and Rural Flood Damage." that was prepared for the Ontario Ministry of Natural Resources and Forestry. See ICCA report at this link.

While nobody would dispute the immense value of wetlands as important natural heritage features in our landscape, their role for flood attenuation is questionable. This is due to the fact that the geographic extent of wetlands is very limited, especially compared to the Laurel Creek watershed analyzed as part of ICCA's report. The headwater subwatersheds upstream of the Waterloo Special Policy Area (SPA) has percentages of wetland of 14% and 17.6%. Many urban catchments in southern Ontario have wetland percentages in the low singe digits (see Kitchener, Guelph, Fergus, Brantford, Mississauga, Markham examples in the slide deck below). Considering rural basins in the Grand River watershed, 86% of subcatchments have a lower percentage of wetlands than the 17.6% Laurel Creek headwater subcatchment. As a result, the effectiveness of wetlands for typical flood attenuation is overstated.

Mapping and analysis is shown in the slide deck below and that was prepared to advise Green Communities Canada on wetland flood attenuation feasibility as part of its Urban Flood Collaborative:

Wetland Flood Reduction - Distribution of Wetland Features and Applicability of Preservation / Restoration on a Broad Scale for Urban Flood Risk Mitigation from Robert Muir

Other reports have evaluated the role of wetlands for flood control and their cost effectiveness including "The Use of Wetlands for Flood Attenuation", the at this link. The citation is as follows:

Williams, L., Harrison, S. and O’Hagan A M. (2012) The use of wetlands for flood
attenuation. Report for An Taisce by Aquatic Services Unit, University College Cork.

The report notes important issues such as (see Section 5)  "Conflicts between flood attenuation and other wetland functions" which notes:

"Protecting biodiversity and enhancing the flood attenuation potential of a wetland are
often thought to be compatible and the two objectives are often conflated. However,
the biodiversity of a given wetland is largely driven by its particular hydrological nature,
which may conflict with flood management. Conflict between flood management and
biodiversity objectives on floodplains can arise with respect to the duration and
seasonality of flooding (Morris et al., 2004). Flood management generally requires the
storage of flood water during the period of peak flows followed by evacuation of flood
water as soon as possible in order to secure the storage facility for re-use. Biodiversity
objectives, however, usually require some retention of water beyond the flood period.
The management of wetlands for birds illustrates this problem. Areas of shallow, smallscale
flooding within floodplains are of critical importance for breeding wading birds. "

It also speaks to Cost Effectiveness (see Section 7). On cost-benefit case studies:

"The idea that wetlands can provide cost-effective solutions to flood management
pervades conceptual literature, but it is difficult to find detailed evidence to support
this. Four international examples are provided, for which some degree of the project’s
cost-benefit analysis detail could be found. There was evidence that schemes do show
cost-effectiveness, but there is also evidence to the contrary. Evidence is confounded
by a lack of detail in how costs and benefits are accounted for and whether these take a
wider ecosystem services approach. Arguments in support of NFM schemes utilising
wetlands draw strongly on the financial benefits in terms of reductions in the cost of
downstream flood damages, however, the cost of implementing such schemes has not
been found to be fully reported. Whilst capital costs of engineering works; maintenance
and so on are often reported, it is unclear if, and how, the cost of aspects such as a
community engagement process, land purchase, and ongoing management for
biodiversity goals are included. As already discussed above, many of these projects may
not be feasible under traditional cost-benefit scenarios, and would not have reached
implementation without some form of additional funding. Where possible the examples
in Table 3 showed how the projects were implemented due to funding from, for
example, WWF, EU LIFE funds, EcoFund Foundation (Poland) and Green Action Fund’
(Polish NGO) (ECOFLOOD, 2006)."

The Toronto and Region Conservation Authority has also identified wetland sensitivities to alterations in the water balance (i.e., how much water is stored in a wetland and when), which would limit the ability to increase flood storage and peak flow attenuation using existing natural wetlands. This is described in their report "Wetland Water Balance Risk Evaluation, Toronto and Region Conservation Authority, 2017" at this link.

The TRCA report notes:

"Wetlands provide many essential ecosystem services in urban and urbanizing areas. The focus
of the Risk Evaluation is on protecting the ecology of a wetland by assessing the risk of a
proposal to the maintenance of hydrological conditions."


"...altering hydrology has the potential to alter the capacity of a
wetland to provide several ecosystem services that are of importance at a watershed scale. "

The report notes further that only where the wetland has low ecological function could alterations to hydroperiods (i.e., changing how much and when water is stored in the wetland) be considered:

" In some cases where the existing level of wetland service provision or ecological function is low,
it may be acceptable for there to be a divergence between the pre- and post-development
hydroperiod such that the ecological function or other wetland services are enhanced."

The Insurance Bureau of Canada, Intact Centre for Climate Adaptation and International Institute for Sustainable Development released a report on natural infrastructure for flood resiliency called "Combatting Canada’s Rising Flood Costs: Natural infrastructure is an underutilized option", available here. Several case studies are presented including one that evaluates the benefit/cost of a reservoir storage / wetland facility called Pelly's Lake in Manitoba.

IBC and report authors conducted 'meta-analysis' to assess the wetland's flood damage reduction benefits - as shown on the following images, flood attenuation was reported as 20% of total benefits:

The net benefit-cost ratio for flood control only would be below unity.

 Meanwhile a 2017 report on the same site reported significantly lower local flood damage reduction values and benefits considering an adjacent Manitoba watershed and literature values. Instead of flood damage reduction representing 20% of the benefits, as IBC calculated, the original analysis, published in Applied Water Science indicates flood benefits of 0.03% to 4% of total benefits.

This comparison shows that local flood damage information (adjacent watershed damages in Manitoba) can result in significantly lower benefits compared to 'meta-analysis' generic literature values, based on world-wide estimated benefits. As Williams, Harrison, and O’Hagan wrote on cost effectiveness, "Evidence is confounded by a lack of detail in how costs and benefits are accounted for.."

Financial Post Identifies Gaps in Insurance Industry Statements on Extreme Rain Causes, Flood Losses Trends, and Effective Mitigation Strategies

Terence Corcoran's article today covers a lot of the science and engineering that has been exploring and promoting over the past few years. It is great to see many of our findings reflected in the mainstream media now. Wow!

Terence Corcoran is a National Post columnist and one of Canada's leading business writers and editors and he has been writing on the insurance industry, climate change and flooding for a couple decades. In his article today he explores the topics of:

1. Catasrophic loss trends, including flooding and the effects of GDP growth on trends as well as the influence of different data sets - we have explored that extensively in a previous post suggesting loss trends are not increasing as dramatically as the media suggests.

2. Green infrastructure implementation costs - we showed that those are prohibitive as in a previous post looking at Ontario-wide implementation city-by-city, and then again when looking at Ontario-wide lifecycle cost in another post.

3. Green infrastructure can make flooding worse - that is due to infiltration into already stressed wastewater systems as noted by the US Transportation Research Board, WEAO, and Ontario and US cities and local experts, as noted in a previous post.

4. Green infrastructure has questionable cost efficiencies as we see in a Metrolinx 'green' parking lot that is actually benefiting from a 'grey' traditional engineered stormwater detention tank- we have further shown that traditional grey engineered infrastructure has a better return on investment than green infrastructure as assessed in a detailed Class EA study and through a city-wide technology review benefit/cost analysis summarized in this post.

5. Green infrastructure and natural infrastructure does not reduce flood damages - contrary to what is promoted by the insurance industry like in the recent IBC report - it does not reduce flood damages according to the Ontario Society of Professional Engineers, and cannot cost-effectively reduce US river flood damages as described in this post.

6. Storms are not more frequent or intense due to climate change, and the insurance industry has made up "Insurance Fact" statements that has been rejected by insurance companies as reliable advertising - this was explored in a previous post and in our paper in the Journal of Water Management Modeling called "Evidence Based Policy Gaps in Water Resources: Thinking Fast and Slow on Floods and Flow";

Thank you Terence Corcoran for helping to shed light on these topics!