ESTIMATION OF PEAK FLOWS FOR NATURAL UNGAUGED WATERSHEDS IN SOUTHERN SASKATCHEWAN

This study developed and evaluated methods to estimate peak flows from unregulated ungauged watersheds, located within the mid to southern parts of Saskatchewan, with a gross drainage area not exceeding 350 square kilometres. The analysis used annual maximum daily discharge records from thirty three currently-operated stations that were not affected by streamflow regulation. Watershed characteristics such as drainage area, drainage density, main stream slope, watershed relief and watershed shape factor were obtained for each of the thirty three basins. Single station frequency analysis of peak flows was performed on the available data of each hydrometric station. Using regression analysis, the peak flows for several return periods were related to the watershed characteristics and regression equations, related to gross and effective drainage areas, were derived for various return periods.