Projected Changes in the Dynamics of Flood Hazard in the Grand River Basin, Canada

In this study future flooding frequencies have been estimated for the Grand River catchment located in south-western Ontario, Canada. Historical and future climatic projections made by fifteen Coupled Model Inter-comparison Project-3 climate models are bias-corrected and downscaled before they are used to obtain mid- and end of 21st century streamflow projections. By comparing the future projected and historically observed precipitation and temperature records it is found that the mean and extreme temperature events will intensify in future across the catchment. The increase is more drastic in the case of extreme events than the mean events. The sign of change in future precipitation is uncertain. Further flow extremes are expected to increase in magnitude and frequency in future across the catchment. The confidence in the projection is more for low return period (<10 years) extreme events than higher return period (10-100 years) events. It can be expected that increases in temperature will play a dominant role in increasing the magnitude of low return period flooding events while precipitation seems to play an important role in shaping the high return period events.