2014 年 70 巻 4 号 p. I_193-I_198
Considering still high uncertainty within results of climate projections by General Circulation Models (GCMs) with various emission scenarios, a multi-model approach after bias corrections and downscaling is very important for climate change impact assessment on water resources at a river basin scale. In addition to the methodologies for selecting GCMs which express regional climate characteristics reasonably, this paper aims to reduce the GCM bias of extreme rainfall where most of GCMs underestimate and improve the poor seasonal variation of GCM bias too. In the Yoshino River, where heavy rainfall events are mainly characterized by the Baiu in June and July and typhoon in August and September, we recognized big bias in extremely heavy rainfalls from June to September. Investigating the tendency of GCMs, seasonal bias corrections were introduced additionally. The results of holistic bias correction and downscaling provide reliable, quantitative and qualitative information to the policy makers for planning for integrated water management in the Yoshino River.