梯级水库调度的发电–生态效益均衡分析

Hydropower-ecologic benefits tradeoff analysis of cascade reservoir operation

梯级水库调度需要同时考虑防洪、发电以及生态等多个目标,对于一些以发电为主要目标的梯级水库,生态流量需求往往是最重要的制约因素。本文以澜沧江中下游三座水库（糯扎渡、景洪和橄榄坝水库）为例,建立了考虑发电目标和生态约束的梯级水库调度模型,定量分析了发电目标和生态流量约束之间的均衡关系。结果表明,在优化调度条件下发电目标和生态流量约束之间存在明确的竞争关系,即发电量增大会导致生态流量相对于自然过程的改变度增加,反之亦然。二者的竞争关系呈现显著的非线性特征,当代表月径流改变度的指标ε在0.3~0.4区间变化时,发电量变化幅度最为剧烈,表明这一区间对于均衡发电目标和生态流量需求具有重要的价值。另外,与自然流量过程相比较,梯级电站调度还会改变高流量脉冲和小洪峰频次,这一现象可以通过增加人造小洪峰调度规则得以改善。

Operation of cascade reservoirs involves multiple objectives including flood control, hydropower generation and ecosystem protection, and environmental flow demand is usually an important constraint if the major objective is hydropower generation. In this paper, we develop a cascade reservoir operation model for hydropower-environmental flow tradeoff analysis, via a case study of the Lancang River cascade, i.e., the Nuozadu, Jinghong and Ganlanba reservoirs. The results show that an obvious competitive relationship exists between maximization of hydropower generation and minimization of environmental flow alteration - the more hydropower generation the more alteration of environmental inflow, and ＂vice versa. This relationship is characterized by fairly strong nonlinearity. When alteration index e is in the range of 0.3 to 0.4, a small change in e can result in a significant change in hydropower generation, thus showing the importance role of this sensitive window in balance between hydropower generation and biological demand. Moreover, relative to the natural river flow, hydropower operation changes the frequencies of high flow pulses and small floods, which can be improved by an operation rule of artificial flood release.