【作者】 杨丽虎；

【导师】 陈进；

【作者基本信息】 长江科学院 ， 水力学及河流动力学， 2007， 硕士

【摘要】 流域梯级开发与河流生态环境之间的矛盾已成为目前流域治理中迫切需要解决的重大问题,为了实现人水和谐,保持河流健康,对梯级水库的生态环境累积影响进行深入系统的研究具有重要的理论和实践意义。我国20世纪下半叶水资源开发的环境影响评价,重点针对单个建设项目进行,研究单个水库对生态环境的影响较多,具有时空局限性,从全流域生态系统完整性的角度分析其叠加产生的累积影响较少,而且理论研究和方法体系也不够完善。水文、泥沙是河流生态系统中两大生境要素,要研究梯级水库的生态环境累积影响,就要从其中最基本的要素水沙研究起,进而扩展到生态系统的累积影响。本文就是根据这一思路,从理论上探讨了梯级水库对水沙的累积影响,进而定性的分析了水沙变化后河流生态系统的适应性响应。文中主要讨论了以下几个方面的内容:首先,为了深入研究流域梯级水库对水沙累积影响的过程和机理,定量的寻求梯级水库建立后水沙变化的规律,提出了流域水沙模拟的新思路和研究框架。从流域宏观角度出发,以梯级水库为主体,以水沙运移为主线,通过多方法联合运用以及多模型集成的途径,将降雨径流模型、水库调度模型、河道水沙模型耦合,建立了流域综合模型。其次,在分析梯级水库对流域生态环境影响的基础上,对水文流量、造床流量、泥沙的累积影响进行了深入的理论总结与分析。针对梯级水库修建后水文特征的变化,提出了一个表征梯级水库对流量累积影响程度的物理量,即均化系数,并给出了其计算方法;为了计算梯级水库拦蓄泥沙的程度,提出了拦沙系数的概念和计算方法。然后,采用金沙江华弹至屏山水文站之间的水文资料验证了流域综合模型,计算结果与实测资料符合较好,利用此模型分析了金沙江下游梯级水库建设后对水沙的累积影响。最后,阐明了河流生态系统及其子系统的内涵,并分析了河流生态系统的特点。流量均化、泥沙拦截使河流的水质产生了相应的变化,河流生态系统的结构与功能发生了适应性的响应,破坏了生物原有的生存、繁殖条件,致使外来物种入侵,生物的多样性降低。在分析河流生态系统变化的基础上,探讨了维持河流健康的对策。更多还原

【Abstract】 The conflict between basin cascade development and river ecological environment has become the biggest problem that should be urgently resolved in watershed harnessing at present. In order to achieve river’s harmonization with humans, and to keep river health, the cumulative effects of cascade reservoirs on ecosystem and environment should be profoundly studied, which will be very important on theory and application.The water resources development focused on assessing individual construction project in the second half period of 20th century in China. It is more to research on effects of individual reservoir on ecological environment, which has space time limitation, whereas it is rare to analyze the cumulative effects of cascade reservoirs from perspective of watershed ecosystem integrality. Furthermore, there is something lacking in theoretical research and methods system.Hydrology and sediment are two important habitat factors in river ecosystems. It should study from the basic factors: hydrology and sediment, and then extend to ecosystem. Based on this research guideline, the paper preliminary discusses the cumulative effects of cascade reservoirs on hydrology and sediment in theory, and then qualitatively analyzes adaptable response of river ecosystem due to the changes in flow and sediment regimes.The key issues discussed in this paper are shown as follows:Firstly, new approach and framework modeling watershed flow and sediment are given in order to profoundly study the cumulative effects process and mechanism of cascade reservoirs, and to quantitative seek the change law of flow and sediment. Comprehensive watershed model, including rainfall-runoff model, reservoir operation model and fluvial sediment transportation model has been developed through integrating multi-methods and multi-models from whole catchment’s aspect.Secondly, on the basis of analyzing cumulative effects on ecosystem and environment, the cumulative effects on downstream flow, bed forming discharge and sediment are deeply analyzed. As to the change of hydrological behavior, averaging coefficient, which is an important physical measure of cumulative effect degree, is defined and the method for calculation is provided. Sediment trapping coefficient is also defined and the method for calculation is provided to compute tapping efficiency of cascade reservoirs.Thirdly, the developed comprehensive watershed model was applied for simulating the runoff distribution and sediment production of the region from gauging station Huatan to Pingshan. The errors between simulated and observed results were acceptable. The developed comprehensive watershed model was also applied to analyze cumulative effects of cascade reservoirs on downstream flow and sediment in lower Jinshajiang.Finally, the concept and connotation of river ecosystem and its subsystems are depicted, and its features are also analyzed. The regulation of water quality is responded to flow variability and sediment trapping. It has become increasingly clear that flow disturbance has been accompanied by major changes in structure of biotic communities, such as alien species invading, biodiversity shrinking, and area of organisms spawning destroying. The special countermeasures are bought forward to maintain the sustainable development of rive health.更多还原