Hydropower-ecologic Tradeoff Analysis for Operation of Cascade Reservoirs

Abstract:

The operation of cascade reservoirs involves multiple objectives, including flood control, hydropower generation and ecosystem protection. For many reservoirs with the main objective of hydropower generation, environmental flow is usually an important constraint. In this paper，we take the cascade reservoirs of the Lancang River, i.e., the Nuozadu reservoir, Jinghong reservoir and Ganlanba reservoir, as a case to develop a cascade reservoir operation model for hydropower-environmental flow tradeoff analysis. The results show that there exists a clear competition relationship between the maximizing of hydropower generation and the minimizing of environmental flow alteration. With the increase of hydropower generation, the alteration of environmental inflow increases, and vice versa. The competition relationship between them shows significant nonlinear characteristics. When the environmental flow alteration index, ε, ranges from 0.3 to 0.4, small change of ε results in significant change of hydropower generation, which shows that this is a sensitive window to balance the tradeoff between hydropower generation and environmental flow. Additionally, compared with the natural river flow regime, hydropower operation changes the frequency of high flow pulse and small flood, which can be improved by increasing artificial flood in operation rules.