Study Of The Eco-environmental Sensitivity Of Upper Changjiang River And Ecological Restriction On Hydropower Development

The water power resources are abundant in the Upper Changjiang River, accounting for86.8%of the whole river basin. Hydropower development in the Upper Changjiang River is an inevitable choose for the sustainable social and economic development in the river basin, and the necessity for current economic development as well. While the excessive development of hydropower gives rise to various complicated difficulties, such as eco-environmental problems like impaired aquatic habitats, partially-polluted waters, change of pollutant carrying capacity, degradation of the wetland functions and etc.. With constant increase of requirement for living environment, these problems become more and more prominent. Some of them have brought significant restriction on the sustainable development of national economy and the life of people. At the same time the further use and the sustainable development of the water resources of the Changjiang River Basin have been affected. So on the basis of the current situation of the key research on the hydropower development and eco-environmental protection in the Changjiang River Basin, the study of the eco-environmental sensitivity of Upper Changjiang River and the ecological restriction on hydropower development on a large basin-level is launched in this paper to provide technical support and scientific foundation for the water resources management and conservation for hydropower development. This study deals with an important issue which receives wide attention at home and abroad in the field of eco-environment.The main research topics and conclusions include:1. the data collection, analysis and identification of the eco-environmentally sensitive areas in the Upper Changjiang River. On the basis of data collection and on-site investigation of all types of ecologically sensitive areas, such as natural reserves, scenic and cultural sites, forest parks, geological parks, world cultural and natural heritages, important aquatic ecological zones and etc., the type, location, grade, quantity and acreage of important habitats and ecologically sensitive areas have been analyzed and identified. In addition, the distribution of ecologically sensitive areas has been defined on the full feature topographic map of the Upper Changjiang River using GIS and RS2. the establishment of the evaluation index system of the eco-environmental sensitivity and the grading. In this study analytic hierarchy process has been employed to establish the evaluation index system. The hierarchy includes target, type, sensitive factor, index and variables. The weights for the nine sensitive factors, namely natural reserves, forest parks, geological parks, world cultural and natural heritages, areas distributed with rare and endangered plants, reserves for important aquatic organisms, reserves for fishery germplasm resources and other key habitats, are0.21,0.07,0.08,0.08,0.09,0.12,0.16,0.12and0.07respectively.At the same time, on the basis of consultation, justification and performing calculations with real data, the eco-environmental sensitivity in the Upper Changjiang River are classified into five grades, namely extremely sensitive, highly sensitive, medium sensitive, low sensitive and no sensitive. 3. the calculation and comprehensive evaluation of the eco-environmental sensitive of the Upper Changjiang River. On the basis of the evaluation index system, the value of the sensitivity is calculated through combination of GIS technology and analytic hierarchy process. The comprehensive evaluation map of the eco-environmental sensitivity is formulated with the calculation result.Large part of the Upper Changjiang River are areas with no and low sensitivity. And the extremely and highly sensitive areas are mainly located in the Upper Jinshajiang River, the main stream of Upper Changjiang River and the Chishuihe River. The areas with medium sensitivity are mainly located in the middle stream of Jinshajiang River, Mintuojiang River, Baishuijiang River and Fujiang water system. The latter two rivers are the tributaries of the Jialingjiang River. The Jinshajiang River Basin is an area with highest eco-environmental sensitivity, and natural reserves are the most important sensitive factor and the restrictions for hydropower development in the Upper Changjian River. In addition, the suggestion on the optimization and adjustment of the hydropower development in the Upper Changjiang River is proposed using graphic overlay method based on the comprehensive analysis of the sensitivity and correlated laws and regulations.4. the study, of the restriction on the typical eco-environmental factor by hydropower development in the Upper Changjiang River. Based on the study on the above mentioned theory and techniques, two-dimensional dynamical model of turbulent flow and longitudinal one-dimensional model of river water temperature are established to simulate the cumulated influence on water temperature of the reservoir and downstream arising from the cascade hydropower development along the Jinshajiang River.It can be concluded that the even annual water temperature and time lagging behind represent the main cumulated influence of discharged water from cascade outlets. The downstream section where receives influence extends and the water temperature increases generally. The tributary influx helps the retrieval of temperature.In addition, the dynamic model of plant growth is set up to simulate the variation of terrestrial biomass which is created by the change of temperature and light intensity after the formation of the Three Gorges Reservoir and to analyze the influence on terrestrial plant from the microclimatic variance with the construction of reservoir.