Features of Eco-Environmental Changes in Heihe River Basin over Recent 10 Years
WANG Gen-xu 1,2, WANG Jian1, WU Yan-qing1 (1.State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environment and Engineering Research Institute, the Chinese Academy of Sciences, Lanzhou, Gansu 730000; 2. School of Resources and Environmental Sciences, Lanzhou University, Lanzhou, Gansu 730000)
Selecting the 13 items of land use or land cover index, which indict the changes of regional eco-environment, from the remote sensing data of 2000 over the whole river basin with an area of 13.0×104?km2. At the same time, the remote sensing data from 1987 was analyzed to output the eco-environmental index of 1987. Comparing with the two time phase analysis results of eco-environmental index, and integrating the field surveying results, the trends and extent of eco-environmental changes in the Heihe River basin were analyzed. The features of eco-environmental changes were quantitatively discussed. Those features showed that, in recent 10 years, the eco-environment of the Heihe River basin was degrading as a whole. Forest area in the river basin decreased by 6.35%. The middle reaches, which replaced the lower reach, was the most serious desertification region, and the upper reaches was the rapidly exacerbated desertification region. Grassland ecology showed a continuous degradation tendency in the lower reaches, the total area of degraded grassland occupied 2?095.39?km2. But in some regions of the river basin, the eco-environment was improved.