2023 Volume 36 Issue 1 Pages 52-62
The feasibility of ensemble reforecast data in dam operations was investigated for the heavy precipitation event of July 2018. Analysis of rainfall forecasts by an ensemble prediction system suggested that it might have been possible to identify a signal of significant precipitation six days before the time of peak discharge at the Kanogawa Dam and a high probability of significant precipitation (kind of precipitation that occurs once every 50 years) three days before the time of peak discharge. It is difficult to foresee a probability of great amounts of precipitation soley by observing the forecast by the control member of the ensemble forecasts or the forecasts by the high-resolution global model. Anticipating various possible scenarios from the results of multiple forecasts by the ensembles is important. In this case, by comparing the ensemble forecast results with the model climate values from the reforecast data, the probability of occurrence of significant meteorological phenomena can be estimated more quantitatively. The reforecast data are useful as a reference for effective dam management and its decision-making such as pre-release operation.
