Soil Erosion Regularity in Three Gorges Reservoir Area and its Controlling Measures

摘要

The Three Gorges Reservoir Area is one of the most severe soil erosion in China. Serious erosion has degraded the soil productivity, deteriorated the ecological environment, and influenced the service life of Three Gorges Reservoir. The natural and social-economic factors which influence the soil erosion in Three Gorges Reservoir Area include topography, geological situation, vegetation, rainfall characteristics, human activity, soil feature, such as infiltration, antiscour ability, etc. Based on the relationship between these factors and soil erosion, several laws of soil erosion are systematically expounded and summarized. Those are: (1) According to the difference of topography, geological situation, the form and degree of soil erosion, four regionalizations of erosion are divided; (2) With the degradation of vegetation, the erosion area and erosion intensity are developed and deteriorated; (3) The erosion types are gradually erosion (such as sheet erosion and gully erosion) and abrupt erosion (such as gravity erosion); (4) The peak of soil erosion in sloping farmland comes forth from April to May, while the peak in river channel comes forth from July to September; (5) Sediment source mainly comes from slope land, land slide, mountain slump, and debris-mud flow. On the bases of sufficiently understanding soil erosion laws of Three Gorges Reservoir area, the control countermeasures which includes vegetation restoration, terracing on the slope, soil reservoir construction and comprehensive control of small watershed are pointed out.