Abstract
Danjiangkou reservoir area is the main water source and the submerged area of the Middle Route South-to-North Water Transfer Project of China. Soil erosion is a factor that significantly influences the quality and transfer of water from the Danjiangkou reservoir. The objective of this study is to assess the water erosion (rill and sheet erosion) risk and dynamic change trend of spatial distribution in erosion status and intensity between 2004 and 2010 in the Danjiangkou reservoir area using a multicriteria evaluation method.The multicriteria evaluation method synthesizes the vegetation fraction cover, slope gradient, and land use. Based on the rules and erosion risk assessment results of the study area in 2004 and 2010, the research obtained the conservation priority map. This study result shows an improvement in erosion status of the study area, the eroded area decreased from 32.1% in 2004 to 25.43% in 2010. The unchanged regions dominated the study area and that the total area of improvement grade erosion was larger than that of deterioration grade erosion. The severe, more severe, and extremely severe areas decreased by 4.71%, 2.28%, and 0.61% of the total study area, respectively. The percentages of regions where erosion grade transformed from extremely severe to slight, light and moderate were 0.18%, 0.02%, and 0.30%, respectively. However, a deteriorated region with a 2,897.60 km2 area was still observed. This area cannot be ignored in the determination of a general governance scheme. The top two conservation priority levels cover almost all regions with severe erosion and prominent increase in erosion risk, accounting for 7.31% of the study area. The study results can assist government agencies in decision making for determining erosion control areas, starting regulation projects, and making soil conservation measures.
Highlights
Soil erosion is considered to be a major environmental problem since it seriously threatens natural resources, agriculture and the environment [1]
The slope gradient in the Danjiangkou reservoir area was divided into six classes with limits of 5°, 8°, 15°, 25°, and 35°, accounting for 8.66%, 8.57%, 20.89%, 30.29%, 21.28%, and 10.31% of the total study area, respectively
The erosion risk of the study area in 2004 (Figure 7a) and 2010 (Figure 7b) were assessed by grading the vegetation fraction cover and slope gradient datasets according to the classification indices of the erosion risk for all land-use types, except for water body and construction land
Summary
Soil erosion is considered to be a major environmental problem since it seriously threatens natural resources, agriculture and the environment [1]. It is one of the main processes that reduce soil productivity by removing fertile topsoil layers [2]. Soil erosion often causes negative downstream effects, such as the sedimentation of soil material in reservoirs and lakes or damage to infrastructural facilities [3]. Serious soil erosion has been and is degrading soil and water resources. It leads to the degeneration of climatic and ecological environments, and hinders the development of society and economy
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