| The Pampanga River Basin in central Luzon Island, Philippines, has been suffered by floods due to typhoons or monsoonal rainfall every year. Flood risk change on global warming is, therefore, an important issue in this vulnerable area. We studied rainfall distribution change in present (1979-2003) and future (2075-2099) climate projection derived from MRI-AGCM 3.2S (Meteorological Research Institute- Atmospheric General Circulation Model version 3.2 Super high-resolution) experiments. The atmospheric fields were dynamically downscaled by using a regional model WRF (Weather Research and Forecasting) into 5km resolution fine enough for streamflow and inundation simulation in this river basin (catchment size of 11,000 km2).Those biases were corrected in the basis of cumulative distribution mapping between downscaled and raingauge rainfall. The bias corrected rainfalls by three different cumulus schemes were consistent with observation in terms of extreme rainfall in same recurrence periods and monthly rainfall, in basin average basis. However, with regard to monthly rainfall in tributaries, Grell scheme performed better. Finally, we found the extreme rainfall in 20 years recurrence period would be increased about 40 percent in future climate projections in RCP8.5 scenario. |
