干旱区生态环境知识资源中心

One of the Yangtze River sources, Qumar River valley was selected as the research area. Landsat Thematic Mapper (TM) imagery were very useful in detecting and monitoring the land cover change, especially in the desolate and bad physical environment region like Tibetan Plateau. In our work TM images in 1994 and land cover map in 1980s were selected to detect and monitor the land cover change. The satellite images were calibrated, registered and georeferenced, then classified and visually interpreted. Ancillary data such as were used to assist the satellite image classification and interpretation. Seven land cover types were obtained, that is, residential area, meadow steppe, alpine meadow, alpine steppe, water surface, exposed rock and desert land. The statistical results of every class land cover type indicated that the desert expanded significantly, about 194km(2), a very big number. The climatic change maybe is the main reason, but the human activity, for example, digging gold in the northwest of this area, is also maybe an important affecting factor. Secondly, the meadow steppe distributed in the low reaches of Qumar River decreased significantly, its change maybe is relevant to climatic change. The variation trend of other land cover type is not significant. All of this showed the significant degeneration of ecological environment of the source of Yangtze River.