ASSESSMENT OF PROBABILISTIC FLOOD FORECASTING USING ENSEMBLE NWP RAINFALL WITH 30HR FORECAST TIME DURING TYPHOON EVENTS

抄録

On early September, 2011, Typhoon Talas caused local heavy rainfalls over the Kinki, Chugoku, Shikoku and Tokai regions in Japan. The operational meso-scale model of the JMA generally predicted the typhoon track well in the early period. However, the rainfall intensity was weaker than expected, and the movement was also faster when the lead time was longer. This study aimed to assess whether the latest ensemble NWP outputs with 30hr forecast time and 2km horizontal resolution from MRI can produce suitable rainfall predictions or not, and to assess the hydrological applicability of ensemble flood forecasts driven by the latest ensemble NWP rainfall. As a result, ensemble rainfall prediction produced more suitable results compared with a deterministic control run in terms of QPF. Ensemble flood forecasting driven by ensemble rainfall forecasts could also produce comparable results in comparisons of observed data, although the maximum peak discharge value was underestimated.