REGIONALIZATION OF A HIGH-RESOLUTION DISTRIBUTED RAINFALL-RUNOFF MODEL TO FORECAST FLASH FLOOD IN UNGAUGED URBAN CATCHMENTS

抄録

 This study aims to generalize a high-resolution distributed rainfall-runoff model to realize discharge predictions in ungauged urban catchments by applying identified general hydrological parameter sets corresponding to land-use categories. The parameter sets were identified and examined at 32 urbanized small catchments located in Osaka Prefecture. To obtain general hydrological parameter sets, parameter values of 1K-DHM, a high-resolution distributed rainfall-runoff model, were obtained for each land-use category so that the simulated discharges could fit with those calculated by the synthetic rational formula method (SRFM). Additionally, the parameter values of the two dominant land-use types were estimated using the Shuffled Complex Evolution optimization method (SCE-UA), and these were replaced with the previously obtained parameters. These two identified parameter sets were validated for 30 catchments with three rainfall events. According to the validation results, we found that the 1K-DHM with the two parameter sets showed better performance than the SRFM in peak discharge estimation and Nash efficiency. Furthermore, the two identification methods showed similar prediction ability in terms of the NSE evaluation, and the latter generated better results regarding stricter NSE value. These findings suggest that a distributed hydrological model with generalized parameter sets based on high-resolution catchment information has the potential to achieve discharge forecasts of flash floods in small ungauged urban catchments.