水电作为一种可持续的能源，其开发面临着诸多的挑战，尤其是近年来不断推广的水电梯级开发，严重的影响着流域复合生态系统。雅砻江流域位于我国西南干热河谷区，生态系统较脆弱，地形起伏大。因此，正确认识水电工程扰动下流域生态系统变异过程及规律，是保证水电开发与生态环境协调发展的基础，也为流域管理提供一定的理论支撑。本文基于3S技术、实地调研、实验室分析、系统模拟等手段，结合生态学、环境学、地理学、水文学等学科的理论基础，定量与定性相结合的分析了水电工程尤其是梯级开发扰动下的流域生态系统变异规律，主要从水生生态系统与陆生生态系统两个层面上分析了生态效应，并在此基础上建立了基于干扰性、适宜性、多样性、连通性、稀有性五个指数3个层次的生态评价指标体系，并给出了指标的定量化模型，利用熵权法与模糊综合评价法对雅砻江下游开发的锦屏一级、锦屏二级、官地、二滩四级水电站进行了生态影响综合评价。主要研究内容如下：（1）通过对雅砻江下游流域进行实地调研，统计分析鱼类种群及其生境的变化。研究结果表明：①二滩水库建库前，鱼类大部分是野生品种，而建库后以鱅、鲢、草鱼、鲫等饲养鱼类为主，这些外来鱼类种群更适应库区的静水生境，很快就形成优势种群，挤占了原来土著鱼类的生态位；②二滩库区上游河道水温均值为19.57℃，而库区水温均值为22.97℃，库区水温较河道抬升了17.4%；③二滩库区上游河道pH均值为7.9，二滩库区pH均值为8.9，比上游河道增长了12.66%；④二滩库区上游河道DO平均含量为6.45mg/L，二滩库区为3.06 mg/L，DO含量库区较河道下降了52.6%。（2）利用生境适宜性模型（HSI）评估了水电梯级开发扰动下河道生境对裂腹鱼属的适宜性程度，锦屏一级到二滩大坝之间河道的HSI值介于0.7～0.9，较适合裂腹鱼生存，二滩库区HSI值为0.29～0.41不适合裂腹鱼类生存和繁殖。各单因子的适宜性情况，总体上pH的适宜值最低，可见在雅砻江pH值对裂腹鱼类的影响较大，二滩库区溶解氧的适宜值低于pH的适宜值，对于裂腹鱼类来说溶解氧起来了主要的影响作用。（3）针对陆生生态系统，本文采用趋势线分析法、偏差分析、相关分析法等方法，分析了流域1982～2006年24年间的植被覆被时空动态变化过程。研究结果表明：年最大NDVI值递减0.0004/a，多年植被覆被度状况：下游>中游>上游，而通过趋势线分析植被覆盖度增减情况是：上游>中游>下游。中下游的植被覆盖度多年来呈现出递减趋势这可能与电站建设活动及气候变异有关。二滩库区5km内缓冲区分析可知建库后NDVI值有所下降，与建设前有显著性差异（P=0.001）。（4）在水电工程扰动下流域生态影响分析基础上，基于干扰性、适宜性、多样性、连通性、稀有性指数，借助层次分析法建立了3个层次19个指标的生态评价指标体系，并给出了指标的定量化模型。利用熵权法及模糊综合评价法对下游四级电站生态影响进行综合评价，评价结果为，锦屏一级水电站评价区生态系统健康度为0.554，锦屏二级水电站为0.543，属于一般状况，官地水电站为0.682，属于良好状况，二滩水电站为0.462，属于较差状况，生态健康度较二滩建设前下降了32.95%。

As a renewable and sustainable energy source,it offers a great deal of challengs in the process of hydropower development,especially for the unceasing advocated of cascade hydropower development recently, it influences the complex ecological system of catchment badly.Yalong River Basin is located in dry-hot valleys of Southwest China. The Ecosystems are more vulnerable and have a large terrain.So,it is very important to understand and identify the rule of variation of the basin’s ecosystems under the disturbance of hydropower development. It is the foundation to coordinate the relation between the hydropower development and ecological environment.Meanwhile, it may provide theoretical support for watershed management.The research is based on 3S technology,field research,laboratory analysis and system simulation tools. Combination the theoretical basis of ecology,environmental science,geography, hydrology and other disciplines.Quantitative and qualitative analyze the variability of ecological impacts under the disturbance of the hydropower projects,especially the cascade development.Aquatic ecosystems and terrestrial ecosystems are two levels of the ecological effects.On such basis,established ecological evaluation index system that include the interference, suitability, diversity, connectivity, rarity of three five-level.And gives quantitative model for every index.Entropy weight and fuzzy comprehensive evaluation methods are used to assessment the ecological impact of the JinpingI, JinpingII, Guandi, Ertan hydropower station of Yalong River. The study Mainly includes as the followings:（I）Through field research of Yalong River basin,analyze the fish population and habitat changes.The results show that, ①Before the construction of Ertan Reservoir, the majority of fish is wild species.But after that, the reservoir have more bighead carp,silver carp,grass carp,crucian carp and others.Because the exotic species adapt to still water habitats of the reservoir area,and they quickly formed a dominant species,occupied the niche of the original indigenous fish;②The upstream of Ertan reservoir have the mean river water temperature 19.57 ℃,while the mean river water temperature of Ertan reservoir is 22.97℃,which rose by 17.4%;③The upstream of Ertan reservoir have the mean pH value 7.9, Ertan mean pH value is 8.9, which rose by 12.66%;④The upstream of Ertan reservoir have average DO content of 6.45mg / L,while the Ertan reservoir was 3.06 mg / L, which rose by 52.6%.（II）Using habitat suitability models (HSI) to assessment the river habitat suitability of Schizothorax under perturbation hydropower cascade development.The river from JinpingI to Ertan dam have the HSI values range between 0.94 to 0.99,whicn is more suitable for the survival of Schizothorax,but the HSI value of Ertan Reservoir is range between 0.29 to 0.41,whicn is not suitable for fish survival and reproduction. The suitability of the single factor，pH had the lowest value,so it may greater impact on the fish.In Ertan reservoir,the suitability of dissolved oxygen is lower than the pH,so dissolved oxygen plays a main role on the control of fishes.（III）As the case study of Yalong River hydropower development, using the trend line analysis, correlation analysis and other methods to analyse the vegetation cover dynamics between 1982-2006 years on the Spatial and temporal scales.The results show that, the annual maximal NDVI reduced 0.0004 every year. Vegetation cover degree status is that, the lower stream is better than the middle stream, while the middle position of basin is better than the upper stream. Middle and lower stream’ vegetation cover shows a decreasing trend over the years which may be caused by the station building activities and climate variation.（IV）On such basis,established ecological evaluation index system that include the interference,suitability,diversity,connectivity,rarity of three five-level.And gives quantitative model for every index. Entropy weight and fuzzy comprehensive evaluation method are used to assessment the ecological impact of the JinpingI, JinpingII, Guandi, Ertan Hydropower Station of Yalong River.The ecosystem health degree of JinpingI Hydropower Station is 0.554,the values of JinpingII Hydropower Station is 0.543,the values of Guandi Hydropower Station is 0.587, the values of Ertan Hydropower Station is 0.538.Overall, levels of ecological health of Yalong River hydropower is a general situation.Ertan Hydropower Station had the lowest ecological health degree,while,Guandi Hydropower Station is the highest. The scores have a good consistency of the size and completion time of hydropower station.