RESEARCH ON THE OPERATION RULE OF KANOGAWA DAM BASED ON ESTIMATED MEAN FLOOD DAMAGE IN HIJI RIVER BASIN

Abstract

 In July 2018, Hiji river basin experienced a severe flood. Right after this flood, residents in the Hiji River basin and the government disputed over the operation rule of the Kanogawa dam and Nomura dam in the basin. This research aims to quantify the proper operation rules of the Kanogawa dam. Dam operation rules are quantitatively evaluated based on expected annual flood damage, which is calculated based on previous flood damages and the extreme value distribution of inflow into the dam. First, the previous and current rules are modelled, and the expected annual flood damage after the dam operation are calculated. In this simulation, the old rule proves to reduce the expected annual damage compared to the new rule. Second, the optimized dam operation rule, which can minimize the expected annual damage, is determined by changing the parameters of the dam operation. It is proven that the rule which aims to reduce the damage of extremely large floods is more optimal. Third, the expected annual damage of flexible operations, in which the operation rule is switched according to the predicted magnitude of inflow, is examined. The results shows that the expected annual damage can be decreased by switching rules, however, the results are almost the same as the expected annual damage of the rule which is optimal exclusively for large floods.