THEORETICAL CONSIDERATION ON FUNDAMENTAL DESIGN OF RIVERSIDE RETARDING BASIN IN ANTICIPATION OF CLIMATE CHANGE

Abstract

 Due to intensification of rainfall external forces due to the climate change, attention is focused on the development of riverside retarding basins. In this research, a theoretical consideration was conducted on fundamental guidelines for optimally designing the retarding basin based on hydrograph of flood discharge from upstream. First, the flood hydrograph was given in a mathematical form including peak discharge and peak time, and for the water level of river channel obtained, the retention process of the retarding basin due to inflow from an overflow levee was formulated. Based on the solution, optimal specifications of the overflow levee to effectively utilize limited capacity of the retarding basin were derived, and the relationship between the retarding basin capacity and the peak discharge reduction effect was expressed. Finally, regarding the changes in flood hydrograph due to the climate change, trial calculations were made of the amount of reduction in flood control effect of the existing retarding basin and the capacity of retarding basin required to obtain specified flood control effect. Although the theoretical development in this research is based on several assumptions, it provides fundamental guidelines for creating the optimal retarding basin plan for arbitrary flood hydrographs.