Impact of water storage and flood detention by reservoirs under construction on joint flood control methods in river basins

Abstract

[Objective] To address the flood detention effect during the impoundment phase of reservoirs under construction and the coordination of flood control scheduling among cascade reservoirs, and to explore a dynamic allocation mechanism between impoundment in under-construction reservoirs and flood control storage capacity in existing cascade reservoirs to improve the efficiency of floodwater utilization and achieve coordinated optimization of flood safety and power generation benefits. [Methods] Taking the Yalong River cascade reservoirs as the study subject, a joint scheduling model for cascade reservoirs was developed. The Muskingum method was applied to simulate the flood process based on the design flood of a typical year. Combined with the storage constraints during the impoundment period of the Lianghekou Reservoir, the equivalent ratio between the impoundment volume of the Lianghekou Reservoir and the flood control storage capacities of the downstream Jinping I and Ertan Reservoirs was quantified. [Results] The result showed that when the Lianghekou Reservoir aimed for an impoundment level of 2 835 m during its initial operation period(2022), it could effectively replace 1.592 billion m³ of flood control capacity in the downstream cascade reservoirs. Under the premise of ensuring flood control safety in the basin(flood control capacity≥2.5 billion m³), the dynamic regulation range of the total usable capacity of the cascade reservoirs could reach 2.6~4.2 billion m³. In actual scheduling, joint operation of the cascade reservoirs raised the water levels of the downstream Jinping I and Ertan Reservoirs, thereby avoiding reservoir water spillage. [Conclusion] The result show that the flood detention effect during the impoundment phase of reservoirs under construction can be incorporated into the joint flood control scheduling system of cascade reservoirs. By optimizing the impoundment process, the floodwater utilization efficiency can be improved, and flood safety and power generation benefits can be coordinated. It provides a solid water resource foundation for ensuring power and water supply security, as well as scientific support and an engineering demonstration for joint flood control scheduling during the impoundment phase of under-construction reservoirs in the basin.

Keywords

reservoir under construction / water storage and flood detention effect / joint flood control method / floodwater utilization / influencing factors