Detection of Ecological Environment in Qinghai Lake Basin by Remote Sensing and GIS

摘要

Qinghai Lake, the largest inland saline lake in China, one of seven famous international wetlands, lies in the northeast of Qinghai Province and the northeast of Qinghai-Xizang (Tibetan) Plateau. The eco-environmental changes in water bodies, desertified land and grassland in Qinghai Lake basin were detected for the period from 1975 to 2000 based on remote sensing and GIS. From 1975 to 2000, the lakeshore shape had changed much, especially in the west shore near the Bird Island and Buha River, in the north shore near Shaliu River and in the east shore near Sha Island and Haiyan Bay. The area of Qinghai Lake decreased by 150.36km{sup}2, the water body about 100km{sup}2 being separated from Qinghai Lake and water level dropped about 2m. The famous Bird Island was connected to the land in the 1970s. Desertified land had kept a sustainable developing situation, increased by 778.65km{sup}2; the average speed of increase of land desertification from 1956 to 2000 was 17.31km{sup}2 per year, whereas the speed rose of up to 32.95km{sup}2 per year from 1986 to 2000. Grassland decreased by 296.41km{sup}2, had been mostly changed into cultivated land and sand, moreover, the degradation of grassland had been serious. Though, warmer and drier climate primarily results in these changes, human activities have a direct influence on land desertification and grassland degradation. In a word, ecological environment has worsened distinctly in Qinghai Lake basin.