Flood hazard maps in Manitoba; present status and future provincial plans with respect to climate change

Flood risk maps currently in use by the province of Manitoba were created in the 70\u2019s and 80\u2019s under the Flood Damage Reduction Program (FDRP) of the federal government. Manitoba FDRP maps only contain information about the extent of flooding occasionally delineating the floodway and no information about flood velocities. These maps have not been updated and other than a few other recent maps that were created at the request of entities other than the province, no other new flood hazard map exists. It is believed that because of topographic, land use, flood frequency, and climatic changes, the FDRP maps generally need updates and new maps are needed for new locations. Particularly, how the future climatic changes impact Manitoba flooding has not been scientifically studied and considered for future flood hazard mappings. This is mainly because the province believes that present climate models do not provide sufficient accuracy, confidence and details required. The province has however been taking several measures to prevent and mitigate future flood damages including the increase of the regulatory flood to 1:200 year, the continuous update of Intensity-Duration-Frequency curves and the construction of several community dykes, to mention a few. The province is additionally planning to produce new flood hazard maps for three watersheds under the Federal Government National Disaster Mitigation Program. In addition to details of available flood maps in Manitoba, the present report lists several available data sources essential for future map generations. To include flood-related recommendations in Canadian building codes, the existing knowledge about how flooding impacts public infrastructure needs to be collected and analyzed and if this knowledge does not exist, it needs to be created. How flood depth, dynamics, and derbies including ice, rocks and boulders will threaten public infrastructure needs to be considered and risks associated with each adverse effect of flooding need to be quantified. This quantification of risks which will be the basis of the upgrade of Canadian building codes has to be based on both present and future climatic trends.Peer reviewed: NoNRC publication: Ye