ECOLOGICAL AND ENVIRONMENTAL CHANGE INVESTIGATION THROUGH REMOTE SENSING AROUND LONG YANGXIA RESERVOIR, QINHAI PROVINCE

Using American Landsat ETM, TM imagines data, the ecological and environmental change investigation through remote sensing in the region around Longyangzxia Reservoir in 1987 and 2000 was carried out. The results show that around the Longyangxia Reservoir region, the physiognomy can be divided into 19 categories, of which the areas and distributions have been found out. The analysis of the dynamic changes in ecology and environment from 1987 to 2000 around the region of Longyangzia Reservoir indicates that the areas of water, dene and natural grassland are all changed. The areas of rivers and lakes decreased by 9.78 km² and 4.82km² respectively. Up to 2000, the most part of the riverbeds was bare; Qiabuqia River had been dried out; and almost all the lakes in this region had shrunk to some extent. The distributions of the sand lands had the same changes mostly; its area increased by 5.08 km² annually; and the sporadic sand hills have joined together into large-scale dense sand hills. The total area of the grasslands decreased by 59.47 km², and its annual degreesive rate was 0.35%.