NUMERICAL STUDY ON FLOOD CONTROL FUNCTION OF RUNNING WATER TYPE RETARDING BASIN LOCATED ALONG VALLEY BOTTOM PLAIN RIVERS

Abstract

 According to the concern about increase in heavy rainstorms due to global climate change, it is required to enhance the flood retention function in the upper river reach in order to improve the safety level against flood disaster. This paper discusses the possibility of introducing a new type flood control facility, called "running water type retarding basin (RWRB hereafter)", on narrow floodplains in a valley (FPV hereafter). A model of FPV having a meandering river channel and remain of old river channel periodically was constructed based on topographic maps and various materials for river planning. An overflow weir and a levee opening was installed at the upstream and downstream ends of RWRB for each floodplain along the meandering channel, respectively. Numerical flood flow simulation on the FPV equipped with RERB showed that the RWRM decreased the peak flood discharge with 5 % in a distance of 3.7 km without causing a severe inundation on the floodplain.