Analysis Of Aquatic Ecological Environment Impact In Hengjiang River Hydroelectric Power Development

Hydroelectric power is a clean and renewable energy which plays an important role in energy development strategy. Hydroelectric power development brings the development and utilization of abundant natural resources. Cascade hydroelectric power development is a principal mode at present in China. It brings economic and social benefits while it impacts ecological environment of drainage basin as well.Hengjiang River, a branch of downstream of Jinsha River, is one of the medium sized rivers rich in water resources. This paper focuses on researching part from Yanjin to Hekou, which is the lower area of Hengjiang River and about95.0kilometers. The hydroelectric power development in Hengjiang River totally has seven power stations from upper to bottom named Sayutuo, Wannianqiao, Yanzipo, Yangliutan, Dayukong, Zhangwo and Fulongkou whose developing pattern are all block river plants.Through surveying and investigating the aquatic ecology and the current aquatic ecologic situation there include species composition, species diversity, group scale and structure and ecological habits of aquatic organisms, the impacts of existing, under-constructing and planned power plants on aquatic ecology at main stream of Hengjiang River have been analyzed. The results indicated that there were no differences in flow rate after the construction of cascade power plants and little influences on hydrological regime and river stability in reservoir. Water in cascade reservoirs exchanges with outside water frequently and its water temperature distribution is the overall-mixed pattern, which guarantees an approximate water temperature with Natural River. Therefore, there is little influence of cascade power plant construction on water temperature in downstream. The construction of each plant has brought changes to varying degrees on variety and biomass of phytoplankton, periphytic algae, plankton and zoobenthos. With the operation of Hengjiang River hydroelectric power development and plan, the river will be separate by the continuous cascades. After that, there will be7Channel Reservoirs in which water flows slowly, water level rises, riffles disappear, sediment gradually deposit, ecological environment and the constitute of fish fauna, population and stock number will change. Moreover, aquatic habitats transform from flow pattern to static or subcritical flow one, which changes the "three" habitats of existing fish a lot. The construction of cascade power plants has no direct impacts on ecological function, constitution and integrity of natural preservation areas and experimental areas for rare and specific fish fauna in Yangtze River at the mainstream of Jinsha River. By researching the impacts of cascade power plants plan on aquatic ecosystem, measures and strategies aiming at buffering impacts and protecting aquatic ecosystem in Hengjiang River, such as multiplication and discharge, conservation areas establishment and ecological operation are proposed in the end.