水电梯级开发对长江中下游水温累积影响机制及生态效应研究

The impact of hydroelectric projects on river water temperature is currently a hot and challenging issue. It is an established fact that downstream temperature in Yangtze River has been altered by the Three Gorges Reservoir. However, such an impact will be more detrimental in the case of large-scale hydropower cascade exploitation in the upper reaches of the river and its major tributaries. Hence, there is an urgent need to investigate the cumulative effects and ecological implication of the upstream hydropower cascade developments on the water temperature in the middle and lower reaches of the river. The proposed project is an interdisciplinary field that includes hydrology, environment and ecology. We analyze the superimposed cumulative impacts scenarios of the hydropower cascade developments on the water temperature. An evaluation for cumulative effects on water temperature will be implemented on the basis of simulation data, which can reveal the mechanism of effects of different hydropower cascade development on water temperature conditions of key fish spawning season. The scientific findings and technical data expected from this study could not only provide key scientific references for eco-operation of cascade reservoirs, but also have a great potential for river management and watershed ecosystem protection.

大型水利工程对河流水温造成的影响是目前生态水利领域研究的热点和难点问题之一。长江上游大规模的水电梯级开发，对已受到三峡水库影响的下游河道水温将产生更为不利的影响。水温过程的改变将会对鱼类繁殖活动产生一定的负面影响，乃至威胁到河流生态安全，迫切需要开展梯级水库群建设对中下游河道水温的累积影响和生态效应研究。本项目采用水科学、环境科学与生态学等多学科交叉理论方法，系统分析长江上游水电梯级开发对中下游水温影响情景，模拟计算梯级水库群对中下游水温过程累积影响，揭示梯级水库对长江中下游鱼类繁殖期水温生态效应，为流域水库梯级群生态调度提供坚实的科学基础和重要的决策依据，在河流科学管理与流域生态安全评估中具有重要的应用前景。

大型水利水电工程对河流生境造成的影响是目前河流生态学领域的热点和难点问题之一。长江上游干流及主要支流的大规模水电梯级开发将进一步影响河流生态安全。本项目主要研究大型水库对长江中下游河道水温条件的累积效应。. 本项目取得的重要研究成果包括：（a）采用GRNN模型重构了无坝情境下三峡坝下河道水温，建立的线性方程，构建了理论评估框架，解析了三峡水库对中游河道水温变化实际贡献；（b）利用Copula理论方法，提出了基于概率模型的梯级水库对河道水温情势影响评估框架，从气温和水量角度推荐了适用于河流管理的生态水温推荐区间，对中华鲟和四大家鱼等重要物种适宜水温保护提供了评估方法；（c）基于深度学习理论方法，构建了长江中下游干流河道水温预测方法，解析水温变化各因子相对贡献；（d）分析了长江上游不同水电梯级开发情景对长江水温影响，构建了水库水热计算模型，结合分布式流域水文模型，模拟分析了水电梯级开发对长江中游生态水温影响，分析了对长江四大家鱼和中华鲟产卵期推迟的影响；（e）通过构建河道水温模型，分析了三峡水库不同蓄水阶段对宜昌—城陵矶河段水温情势演变规律，分析了不同蓄水阶段对中下游河道水温的实际影响，及其对鱼类所需生态水温的影响。. 研究成果丰富了河流生态水文学研究理论和方法，推动了生态水利学科发展，为长江经济带建设，长江流域水资源开发利用与生态保护提供了重要的科学依据。