Optimizing water-energy distribution during short-term flood in cascaded hydropower dams and proposing solution of conflict between stakeholders by bargaining game theory

Reservoirs are one of the major countermeasures against flood, which play an important role in adjusting water flow and reducing flood peak. They often have other roles, generating electricity, storing irrigation water etc. Since there are trade-offs between flood control and water storage for water use, many researches tried to solve multi-objective optimization problems for dam operation methods so far. However, hydropower dams built for power generation, especially owned by private companies, do not participate in flood control because they lose water for power generation when flood control is performed. In addition, detail information and observed data of these dams are often kept secret because it is valuable information for the companies. Therefore, no studies have been conducted to evaluate the effects of hydropower dams when they participate in flood control based on actual inflow and outflow information. The purpose of this research is composed of mainly two parts. One is to evaluate increase and decrease of flood risk and expected value of power generation when hydropower dams participate in flood control. The other one is to develop a negotiation framework of how to motive electric power companies which operate hydropower dams to participate in flood control. Target river basin of this study is Kurobe River in Japan, which has cascaded hydropower dams. First, we developed method to use multiple rainfall prediction to perform preliminary discharge, which lowering water level before flood may come. The results show that both parameters, flood risk and expected value of power generation, was improved compared to conventional operation. Both parameters are evaluated in parallel by monetary value. Second, using bargaining game theory, we simulated negotiation of dam operation between three stakeholders, government, electric power company, and residents. The results show that all three players get more profit if the negotiation conducted before catastrophic flood occurs rather than after flood occurs. We also get concluded that optimal solution was changed if shared information during negotiation was changed. These results quantitatively show that making decisions by stakeholders in advance will increase overall profits.