梯级水电站库区鱼类栖息地适宜性模拟预测与评价研究

Construction of large reservoirs in cascade hydropower development alters hydrodynamic and aquatic environment of natural rivers, causing variation of quality and quantity of fish habitat. Thus it would have a significant impact on survival and reproduction of fish individuals, and structure and quantity of fish populations. Study on the fish habitat requirement and suitability is the basis for fish resources protection. Taking large-mouth bronze gudgeon (Coreius guichenoti), a typical native fish in Jinsha River as the target fish, this study explores to analyze the habitat requirement of key environmental factors for different life stages of the fish and to investigate the fish habitat suitability in reservoirs by coupling hydrodynamic model and habitat model. The hydrodynamic and environmental factors that affect the fish habitat in a selected typical reservoir are firstly simulated and analyzed. By combining the habitat selection and requirement of the hydrodynamic and environmental factors, the habitat model is established, and distribution and area of suitable fish habitat are simulated. The evaluation of feasibility and effectiveness whether the habitat in the reservoirs is suitable for fish reproduction and survival is conducted. On this basis, the suggestion for selection of protected river branch and artificial releasing location in the reservoir for largemouth bronze gudgeon is proposed. The research results can provide scientific support for decision making of fish habitat protection and restoration under the background of cascade hydropower development, such as ecological flow discharge, water temperature recovery, fish passage construction, artificial propagation and releasing and etc. The achievement can also be a basis for risk assessment of biological invasion.

梯级水电站开发中大型水库的建设改变河流的水动力和水环境条件，从而引起鱼类栖息地质量和数量的变化，对库区鱼类个体生存与繁衍、种群结构和数量产生显著的影响。鱼类生境需求和适宜性评价研究是鱼类资源保护的基础，课题拟以金沙江典型土著鱼类圆口铜鱼为研究对象，利用原位观测手段分析鱼类不同生活史阶段关键生境需求，耦合水环境数值模型和栖息地模型，模拟分析梯级水电站库区因水动力学条件变化而导致的各种生境指标变动，进一步模拟分析库区鱼类适宜栖息地分布与范围时空动态变化，评价典型库区作为鱼类适宜栖息地的可行性与有效性，在此基础上，提出库区圆口铜鱼栖息地保护河段选取、鱼类增殖放流选址建议。研究可望支撑水电工程中鱼类栖息地保护与修复的决策，指导提出梯级水电开发中生态流量下泄、水温恢复、过鱼措施、增殖放流等措施的保护要求，推动鱼类资源的有效保护，也可以作为生物入侵风险评估的基础。

金沙江流域梯级水电站开发导致河流流水生境严重萎缩，形成库区和库区相连的局面，在梯级水库运行下，库区水动力环境条件严重影响和决定了鱼类生存和繁殖的栖息地。课题以金沙江特有土著鱼类圆口铜鱼等为研究对象，在利用原位观测数据分析鱼类产卵繁殖和幼鱼生存的关键生境需求的基础上，针对金沙江中游攀枝花附近江段圆口铜鱼关键产卵场，建立了一维和二维耦合水环境数值模型和基于模糊逻辑的栖息地模型，模拟分析了上游水库运行（金沙江干流观音岩水库和雅砻江二滩水库联合作用）不同河道流量条件下鱼类栖息地质量和面积，通过水电站建坝前和运行后的栖息地时空变化对比分析，评价上游水电站运行对鱼类产卵栖息地影响，分析了适合鱼类产卵生态流量的变化；针对下游在建乌东德水电站对研究江段的淹没情景，预测了乌东德水库运行对圆口铜鱼产卵栖息地的影响，进一步拓展建立了针对金沙江流域多维耦合的水文-水环境-栖息地模型框架，预测未来气候变化和水库运行联合作用下圆口铜鱼幼鱼和产卵栖息地变化，评价了气候变化和水库运行对栖息地的时空效应；针对龙开口库区（金安桥水电站-龙开口水电站之间），建立二维鱼类水力栖息地模型，模拟分析了金安桥水库泄水和龙开口水库蓄水的多种联合运行情境下，库区不同相段鱼类栖息地适宜性变化，评价了水库日调节对成鱼产卵和幼鱼存活的栖息地的影响，根据以上研究相应地提出了有利于鱼类生存繁殖的梯级水电站友好运行方案。