Effect Of Danghe River Cascade Hydropower Stations On Ecological Environment

Hydropower development is the main content of the modernization construction in China in the 21 st century, and cascade become the main form of hydropower developmen because of its comprehensive benefit is remarkable. Acrossing SuBei Mongolian autonomous county and dunhuang county, Danghe is an important river, it has rich hydropower resources which can be available for development,and SuBei electric power is not enough, therefore, to establish a cascade hydropower stations in Danghe is imperative. Danghe nourished in dunhuang oasis, the ecological environment is very important. thus,this paper through contrasting and researching the change of ecological elements in Danghe drainage basin after the construction of cascade hydropower stations, understanding the effect of Danghe river cascade hydropower construction on the ecological environment is important.Danghe cascade hydropower stations are diversion-type power stations.At present, domestic scholars mainly analysis and research the influence of dam-type hydropower stations on ecological environment, it is still lack of related research that the effect of cascade hydropower development and diversion type power station on ecological environment.This paper from the water temperature, the river flow, sediment accumulation, river form, terrestrial and aquatic organisms to contrast and analysis of the changers of ecological environment after Danghe cascade power stations constructed.After the construction of cascade hydropower stations in Danghe, river water temperature increased, river flow reduced or even stop, sediment accumulation phenomenon is serious, rivers form by the continuous state into discontinuous nature.The cause of the above changes are mainly the following aspects: the construction of river diversion type power stations need to build water diversion culvert, makes the water inside the diversion culvert affected by geothermal, water temperature increased.Bring in the river water into diversion tunnel and culvert, through water turbine, the river flow in riverway is reduced, in the dry season or the design water flow of plants is large,the river flow discontinuous.Because of the river flow reduced, sediment entrainment effect is reduced, and the power station hub construction content will have a blocking effect of sediment, sediment accumulation phenomenon is serious.Hub for the cascade hydropower stations in the structure of the building, will cut the river cutting, make the river morphology is not continuous.After the construction of cascade hydropower stations in Danghe, aquatic and terrestrial creatures are affected.Fish can’t through the diversion-tunnel and barrage, fish gene exchange is blocked, discontinuous flow can not maintain the survival of fish, and destroy the fish "three place", The number of fish populations dicreased. Causing river slow, water temperature increased and quality of water eutrophication getting high,these changes suitable for the growth and development of plankton, and zooplankton species and quantity increased.Sediment deposition decreases the living space of benthonic animals, the number of benthic animals decreased.Due to power stations cover areas,living space of terrestrial organisms smaller, and land animals migrate.In addition, because the form of rivers is not continuous, will cause the habitat fragmentation and plants’ community structure change.