Soil Erosion Types And Intensity Analysis On The Three-river Headstream Region

The Three-river Headstream Region is located in the hinterland of Qinghai-Tibet Plateau. Its ecosystem is very fragile, and its unique geographical position and the resulting ecological environment have great influence on China's and global climate change and ecological environment. According to the analysis of the spatial variation of soil erosion in this region, the type and the intensity of soil erosion in this region are identified.(1) Based on the collected data on soil erosion and meteorological information, and the existing literature, the exterior forces and the causes of soil erosion in the region are researched. The analysis of the remote sensing data on changes in area of erosion of various types in this region respectively in 1995, 2000, 2005 shows that the area of water erosion decreased in 10 years, reflecting a general downward trend. That is, the slight, moderate, serious, extremely serious levels of erosion reduced, and the area of severe erosion only increased mildly; the area of wind erosion had overall upward trend, mainly with noticeable increase in the slight level of wind erosion; in areas where freeze-thaw erosion occurred, the erosion area increased substantially with the increases in the slight and the moderate levels of erosion.(2)Based on the interpretation of remote sensing data on erosion in 2005, the proportion for each type of soil erosion per county was calculated, and the erosion type with the highest proportion was defined as the county-based dominant type of erosion. Then, according to the principles of geographical similarity and unity, the areas with the similar type of erosion were classified. Thus there exist five types of soil erosion in this region: freeze-and-thaw and wind erosion areas in the west; freeze-thaw, wind erosion and water erosion areas in the middle-west; freeze-and-thaw, water erosion and wind erosion areas in the middle-east; water erosion, freeze-thaw areas in the east and water erosion area in the northeast. The area of water erosion and wind erosion areas in the middle-east is the largest. The area of water erosion area in the northeast is the smallest (3) Based on the actual situation of soil erosion and related standards in this region, soil erosion intensity in the region have 6 levels: slight soil erosion, mild soil erosion, moderate soil erosion, intense soil erosion, serious soil erosion, severe soil erosion. On the basis of interpretation of remote sensing data on erosion in 2005 and classification of soil erosion intensity, the Source Region is major impacted by the slight level of soil erosion, with the mild level of soil erosion mainly spread in the northwest, southwest and northeast; the moderate level of soil erosion in the southwest, north and northeast; the intense level of soil erosion in the northwest, east and northeast; the serious level of soil erosion in the west and a little in the east; the severe level of soil erosion in the east; and with the increase in erosion intensity, the erosion area reduces correspondingly.(4) Integrate the analysis of the soil erosion type and the soil erosion intensity The result shows that the soil erosion in this region is mainly caused by the special and natural and geographical environment and that some changes in types of soil erosion in the region are caused by the global warming.