干旱区生态环境知识资源中心

Satellite remote sensing imaging systems have provided a spatially and temporally continuous and effective method to map the environmental and landscape changes over large areas on the earth's surface. In this study, multitemporal and multisource satellite remote sensing images, including Landsat Multispectral Scanner (MSS), Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), were used to study the environmental and landscape changes happened in Qinghai Lake area from 1973 to 2000. Change detection methods, such as image enhancement and false color composition, were used to highlight the environmental and landscape changes, i.e. lake area shrinkage, desert expansion and cropland area variation. Results showed that: lake area had shrunken by 275 km(2) from 1973 to 2000; in contrast, the area of desert and cropland increased by 287 km(2) and 310 km(2) during the same period, respectively. As a result, remarkable landscape changes have happened: several sub-lakes have separated from the main lake in the east; the famous Bird Island in the west became a peninsula connecting with the land. Analysis suggests that environmental and landscape changes of Qinghai Lake area are mainly caused by natural factors and human activities.