| Water resource is one of the irreplaceable strategic resources for human survival and social development, and the hydropower coming from water resources is one kind of clean energy. The development and utilization of hydropower can replace some thermal power so as to reducing environmental pollution. To make full use of water resource, the exploitation of cascade hydropower in a river basin is an international tendency and also the fundamental hydropower energy policy in China. The development of cascade hydropower can bring enormous social and economic benefits, but it also may have some negative ecological environment impacts (EEI). Eco-environmental impacts assessment (EIA) is one of the most important measures which can minimize the negative eco-environmental impacts induced by cascade hydropower development. However, the EIA is obviously regional and spatial, and the traditional evaluation means based on the traditional ground monitoring network are too inefficiency to meet the needs of management and decision of eco-environment. Whereas the spatial information technologies, especially remote sensing technology and Geographic Information System (GIS), owing to their macroeconomic, fast and economic characteristics, can be powerful technological means for eco-environment evaluation. So far, the spatial information technologies have become important research means of global and regional (basin) eco-environment. In order to estimate the temporal and spatial ecological environment impacts of cascade hydropower, the thesis employs the cascade hydropower development pilot project, Qingjiang River Basin cascade hydropower exploitation, as an example. The quantitative remote sensing inversion methods and GIS have been adopted to qualitatively and quantitatively research the impacts of cascade hydropower development on some key ecological environment factors, such as water environment, vegetation environment and land-use environment. Summarily, the main studies and achievements of thesis are listed as following:Firstly, the TM/ETM+ remotely sensed imageries provided by series of satellites Landsat have been selected as research original data in this thesis based on analyzing the characteristics of multi-source remotely sensed data and the exploitation of cascade hydropower in Qingjiang river basin. Then the quantitative remote sensing inversion techniques of key eco-environmental factors, the data fusion techniques of multi-sources remotely sensed data based on remote sensing, the means of spatial management and spatial analysis based on GIS have been researched in this thesis.Secondly, the water extraction models based on remotely sensed images have been analyzed and two water-body extraction models, such as normalized difference water index (NDWI), modified normalized difference water index (MNDWI) have been employed to extract water resource area from the selected TM/EMT+ images so as to quantitatively study the spatiotemporal impact of water distribution environment caused by cascade hydropower development. The results show that the cascade hydropower development has significant influence on the spatiotemporal distribution of water resources in Qingjiang river basin: before undeveloped in 1987, the total water resource area of Qingjiang middle-downstream is 65.31 km2, and that is 102.25km2 in 2000, and that reaches 112.74km2 in 2004. Compared with 1987, the total water resource area in 2004 increases 72.67%, however, the water resources increase regions and decrease regions coexist in Qingjiang river basin during the course of the cascade hydropower development.Thirdly, the dimidiate pixel model based on normalized difference vegetation index (NDVI) has been adopted to estimate the vegetation fraction based on TM/ETM+ images so as to quantitatively research the impact of cascade hydropower exploitation on the vegetation environment. The results indicate that the cascade hydropower development has significant impact on the vegetation environment in Qingjiang river basin. The vegetation cover types in Qingjiang river basin include three major types, such as middle vegetation coverage, middle-high vegetation coverage and high vegetation coverage. In 1987, the proportion of three major vegetation coverage types are 23.93%, 23.18%, 25.43% respectively, and in 2000, the proportions of three major vegetation coverage types are followed by 15.75%, 21.44% and 45.14%, when come to 2004, the proportions of three major vegetation coverage types are 11.66%, 20.04% and 55.84% respectively.Finally, supervised-classification method based on maximum-likelihood and Geographic Information System (GIS) have been used to quantitatively research the impact of cascade hydropower exploitation on the land-use/land cover-change (LUCC) environment. The results illuminate that the cascade hydropower development has a significant influence on the LUCC environment in Qingjiang river basin from 1987 to 2004. From 1987 to 2000, the 1.77 percent of farmland and 29.24 percent of urban-rural residents have been submerged by the cascade reservoirs after completion two cascade hydropower stations in Qingjiang River. From the 2000 to 2004, the 1.60 percent of farmland and 13.98 percent of urban-rural residents have been submerged by the cascade reservoirs. In a word, the cascade hydropower development promotes regional economic development, and simultaneity the cascade hydropower development also accelerates the conversions between different land-use (cover) types. The land-use structure of Qingjiang River is an unstable and rapid adjustment phase, during two time intervals 1987 to 2000 and 2000 to 2004.In all, the spatial information technology, especially remote sensing technology and geographic information system (GIS), is an inevitable trend and effective mean to quantitatively assess the spatiotemporal impacts of cascade hydropower exploitation on eco-environment. The quantitative assessment results based on RS/GIS show that the cascade hydropower exploitation has significant impacts on spatiotemporal distribution of water resource, vegetation cover environment and land use/ land cover change.
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