Based On Gis In The Source Area Ecological Environment Change And Human Activity Impact Study

Sanjiangyuan source region, located in the Qinghai-Tibet Plateau, is called "thesaurus of water resource in China". However, due to the special geographical environment, its ecological environment is extremely fragile, and self-recovery capability of ecological system is extremely weak. Recently, deterioration of the environment has become more and more serious. And multiple ecological problems, such as the grassland degradation, desertification, glacial retreat, shrinkage of wetlands, have arisen. Therefore, it is important to study eco-environment change and their driving force. Study on land use change is the first step to protect local ecosystem sustainability and will be very important for eco-environmental protection.Based on Landsat TM/ETM images of1987,1997and2007, this paper studied land use/cover dynamic change of Sanjiangyuan source region in different prefecture and watershed, and analyzed the landscape structure and pattern change in study areas. At the same time, according to the results of the quantification on spatial distribution of temple. We built spatial belt transect. Comparison of land use change around the temple and human settlement were analyzed. The impacts of Tibetan Buddhism of the Golog and Yushu prefecture on the landuse change were also analyzed. The results indicate that: 1.From the range of land use change during the period of study, different landuse types in different prefecture existed in obviously difference. There are generality and difference in different watershed. For the source region of the Yellow River, the areas of farmland and forestry has increased, and the building land area increased dramatically; meanwhile, the areas of grassland, water, and unused land are decreasing. In the source region of the Yangtze River, the areas of farmland, building land, and unused land area increased, while the areas of forestry, grassland and water have decreased. In the source region of the Lancang River, the areas of famland, grassland, building land and unused land has increased, while the areas of forestry and water have decreased. In Golog prefecture, the areas of farmland, forestry, and grassland and building land have increased, while the areas of water and unused land have decreased. In Huangnan prefecture, the areas of forestry, grassland, and building land have increased, while the areas of farmland, water and unused land have decreased. In Hainan prefecture, the areas of grassland and building land have increased, while the famland, forestry, water and unused land have decreased.2. The analysis result of the degree of landuse change showed that during the two period of1987-1997and1997-2007, the Zhiduo County, Xinghai County, Tanggula Town, Xiangqian County have changed from the phase of adjustment to the phase of development. The Counties of Qumalai, Maerduo, Zaduo, and Dari have always been in the phase of adjustment. The prefectures of Golog and Huangnan have been in the phase of development. The prefecture of Yushu was in the phase of adjustment, while Hainan prefecture has moved from phase development to adjustment. The source region of the Yellow River has always been in the phase of development while the source region of Lancang River has moved from phase development to adjustment, and the source region of Yangtze River has moved from phase adjustment to development.3. It was found that Sanjiangyuan source region landscape fragmentation increased during the period of study, the diversity of patch reduced, the distribution of landscape pattern tended to be simple, and the whole heterogeneity of landscape in study area had a weakening trend during the period of1987to2007.However, the changes of landscape pattern were different from the whole in spatial view. The degree of landscape fragmentation decreased in different source regions and prefectures. However, fragmentation degree in lancang river source region is higher than other two source region, and fragmentation degree in Golog prefecture is higher than other three prefectures.4. We calculated and compared the landscape fragmentations in the temple buffer zone and the residential spot buffer zone of Golog and Yushu prefectures. The result of Golog prefecture showed that the eco-environment around temples is more better and more stable, and the landscape fragmentation was low. In Yushu prefecture, however, the eco-environment fragmentation near temples is greater than that near the residential spots, and this illustrates the damages of human activities has made to the eco-environment.5. By analyzing the distribution of population density in Sanjiangyuan region, this paper studied the characteristic of spatial-temporal changes during half a century, and the result showed that the population density and dynamic changes of landuse are closely related to the natural, social, and economic status. The spatial pattern of landuse is the key factor that affects the distribution of population. The improvement of the social productivity, the development of economics and the national policies were also factors that affect the population distribution.