A STUDY ON THE UNCERTAINTY IN FLOOD PREDICTION AT THE TSUKINOWA STATION IN THE HIWASA RIVER

Abstract

 Although an early warning system is one of the most effective tools for flood disaster prevention, it is difficult to provide the accurate information predicted due to the uncertainties involved in flood forecasting. In this study, a forecasting experiment was conducted for the Hiwasa River to clarify the forecast uncertainty and accuracy. The results showed that the underprediction of floods was caused by rainfall forecasts, suggesting the effectiveness of wide-area flood forecasting. The forecast uncertainty increased with forecast time. The uncertainty up to three hours ahead was smaller for the typhoons than for the non-typhoons. Furthermore, while the lead time for evacuation is expected to be one hour and thirty minutes, the accuracy rate is 35.7%, which is not high even one hour ahead. Therefore, in order to improve the information literacy for flood forecasting, it is important to provide the forecast information by wide-area and to understand the uncertainties involved in flood forecasting.