Practical Issues in Floodplain Mapping Over Large Regions
Abstract
Flooding events are among the costliest and most frequent natural hazards occurring in Canada. Floodplain mapping is a non-structural flood management strategy that involves the formulation of hydrologic and hydraulic models to produce maps which predict extent and depth of floods. Practices and availability of floodplain mapping vary across Canada. The current state of floodplain mapping across Canada has been identified and reviewed. Vast areas of flood prone regions across Canada have been identified as not having floodplain maps or lacking updated ones. Large region floodplain maps have been recently introduced and can cover national and global regions. Limitations of spatial resolution exist in large region mapping efforts, which hinder their implementation for local scale floodplain management practices. A recent study at Western University produced a national floodplain map with a spatial resolution of 1 km x 1 km. This national floodplain map is highly accurate; however, spatial resolution needs to be improved to be implemented within local scale floodplain studies. The study presented in this thesis developed a downscaling methodology to further improve spatial resolution of the floodplain map. The downscaling methodology was implemented to produce floodplain maps at spatial resolutions of 20m, 40m, 60m, 80m, 100m, 200m, 300m, and 400m for two case study river basins: Bow and Elbow River Basin and St John River Basin. Analysis of the floodplain maps was completed, followed by volume conservation and computational time studies to assess the accuracy of the proposed downscaling methodology and to compare the sensitivity of the downscaling methodology.