Forecasting Coquitlam River Basin, British Columbia

Rain-on-snow events during warm periods with high precipitation amounts can produce high floods. Due to the complexity of the process, predicting run-off during these events is difficult and current conceptual hydrologic models are believed to simulate rain-on-snow events only very poorly. The inability of conceptual hydrologic models to simulate rain-on-snow events correctly may eventually translate into a greater risk adopted into BC Hydro's operations. For this purpose, hydrologic simulations and forecasts of several rain-on-snow events for the coastal Coquitlam watershed, British Columbia, Canada, were selected for analysis. In the first part of this study, the ability of the UBC Watershed Model to simulate Coquitlam Reservoir inflows during rain-on-snow events using observed precipitation and temperature data as model input was investigated using various performance measures. In the second part of this study, performance measures for hydrologic forecasts for the selected rain-on-snow events were calculated and the forecast skill determined.