EVALUATION OF THE CLIMATE CHANGE EFFECT ON THE DISCHARGE OF THE SAYOGAWA RIVER BY MULTI-RAINFALL-RUNOFF MODEL ENSEMBLE SIMULATIONS

Abstract

 The effect of the climate change on the discharge of the Sayogawa river was investitaged using two rainfall-runoff models and d4PDF. A storage function model and a distributed rainfall-runoff/flood-inundation model were applied as the runoff models. Fistrly, the flooding in August 8-9 2009 by Typhoon 9, the historically largest event in the region, was reproduced by the runoff models. Then, the yearly maximum 24 hour rainfalls of d4PDF for the Sayogawa river was analyzed and the 24 hour rainfall - return period relation was summarized. Finally, the peak discharges driven by the hourly rainfall time series of the yearly marimum 24 hour rainfall are analyzed. As the result, it was observed that the peak discharge value of a return period is different according to the runoff models. The discharge with the very intensitve rainfall tends to be higher by DRRFI, a physically based model, which is in general more sensitive to the rapid change of the rainfall. In other word, DRRFI may provide the safer side consideration when applied to river planning.