FUTURE CHANGES OF FLOOD CONTROL EFFECT BY DAM RESERVOIRS OVER JAPAN USING d4PDF

Abstract

 Future changes of flood control effect (FCE) by major existing dams were analyzed for 59 river systems all over Japan using d4PDF rainfall data and the rainfall-runoff model 1K-DHM. The rate of flood peak discharge with/without dams increased for floods over a particular magnitude (FCE was reduced) for some river systems near the Pacific Ocean and not (FCE was remained) for ones near the Seto Inland and Japan Seas. The former has smaller dam capacity despite receiving heavier rainfall, where larger future changes of extreme discharge are projected but its impact was not significant. Similarly, the frequency of emergency operation is also related to the flood storage, indicating that flexible dam operation such as preliminary release will make a significant contribution to flood control in a changing climate in Japan.