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Urban flooding associated with extreme precipitation is a significant cause of disaster damages for municipalities, homeowners and insurers in Canada. Several approaches have been applied to reduce urban flood risk at the municipal and homeowner scales, including addressing inflow/infiltration in wastewater systems, accommodating extreme stormwater flows in subdivision design and protecting individual homes from flooding. Insurers have also engaged in managing urban flood risk through interactions with individual policyholders and initiatives aimed at better understanding urban flood risk and risk mitigation options. Requiring mitigation measures at the time of the construction of homes, improving insurance data, application of incentives for appropriate private side retrofits, and improved collaboration between insurers and municipalities for identification of urban flood risk areas provide additional opportunities for urban flood risk reduction. Further, senior levels of governments should support inflow/infiltration reduction and application of climate change information to improve the planning and design of municipal infrastructure.

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Rainfall Intensity–Duration–Frequency (IDF) curves are among the most essential datasets used in water resources management across the globe. Traditionally, they are derived from observations of historical rainfall, under the assumption of stationarity. Change of climatic conditions makes use of historical data for development of IDFs for the future unreliable, and in some cases, may lead to underestimated infrastructure designs. The IDF_CC tool is designed to assist water professionals and engineers in producing IDF estimates under changing climatic conditions. The latest version of the tool (Version 4) provides updated IDF curve estimates for gauged locations (rainfall monitoring stations) and ungauged sites using a new gridded dataset of IDF curves for the land mass of Canada. The tool has been developed using web-based technologies and takes the form of a decision support system (DSS). The main modifications and improvements between version 1 and the latest version of the IDF_CC tool include: (i) introduction of the Generalized Extreme value (GEV) distribution; (ii) updated equidistant matching algorithm (QM); (iii) gridded IDF curves dataset for ungauged location and (iv) updated Climate Models.

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Urban flooding events are a significant driver of disaster loss, resulting in insured and uninsured losses, property damage, and negative impacts on residents and communities in Canada and internationally. The risk of flooding in urban environments is affected by watershed characteristics, environmental conditions, and the presence and condition of flood management and mitigation technologies. Several building- and lot-scale (or private-side) flood mitigation options are available to better protect properties from the risk of flooding, including backwater valves and foundation drainage systems to reduce the risks of sewer surcharge and infiltration flooding into basements, respectively. The overall success of private-side approaches to reduce the risk of flooding into buildings is reliant upon consistent installation procedures, building code interpretation and enforcement, public engagement, and maintenance. Current research into private-side approaches is presenting many opportunities and solutions for improved flood protection against water-related disasters at home. A greater understanding of the performance of private-side technologies under complex site-specific conditions can help to appoint flood prevention strategies better suited to individual home characteristics. This review paper explores the inter-related factors that affect the risk of basement flooding and explores the challenges and opportunities associated with the adoption and success of private-side flood mitigation approaches. Developing a greater understanding of basement flood vulnerability at the lot-scale will assist in identifying and prioritizing private-side strategies for homeowners to adopt and reduce the risk of flooding based on site-specific conditions affecting flood vulnerability. Continued efforts to evaluate and identify flood risk factors and the performance of private-side strategies are needed to better manage urban flooding events.