Understanding the tradeoff between the flood risk and the hydropower benefit from the integrated flood control operation of a reservoir group and a flood detention basin

Abstract

To mitigate flood disasters and reduce their risks, a lot of reservoirs, as a reservoir group, and some flood detention basins (FDBs) have been constructed. As the flood control targets of the reservoir group and the FDB are often the same or are interrelated, it is necessary to integrate the reservoir group and FDB operation instead of operating them independently. Hydropower benefit is one of the functions of the reservoir group besides its flood control. There should be a tradeoff between the flood risk and the hydropower benefit from the integrated flood control operation of a reservoir group and FDB. A framework is proposed to determine and understand the tradeoff for enhancing decision-making in flood control. It has been applied in a case study of the Jingjiang FDB and a mixed reservoir group (Three Gorges, Shuibuya, and Geheyan) in the Changjiang River Basin. It has been found that the integrated operation of Jingjiang FDB can enhance the exchange between extreme flood risk and hydropower benefit, while this exchange is weakened for the non-extreme flood conditions due to the operational inflexibility of Jingjiang FDB. The safety flow at the downstream protection target has a significant impact on the tradeoff under non-extreme flood conditions but only a slight impact under extreme flood scenarios. The damage coefficient exerts a significant and consistent influence on the tradeoff across both extreme and non-extreme flood conditions. It is critical to determine the damage coefficient and the safety flow for improving the performance of the flood control operation. The proposed framework not only determines the tradeoff between flood risk and hydropower benefit but also helps facilitate the integrated flood control operation of a reservoir group and FDB.