Study On Soil Erosion In Karst Area Based On RUSLE Model

Based on the data of RS,rainfall,DEM and soil, a study of soil erosion of the Catchment of Hongenghu lake located in Karst ecological fragile area in Guizhou Province is taken by using GIS and RUSLE Model. The main contents of the research include: analyzing the characteristics and diving factors of the temporal and spatial distribution and variation of soil erosion in the past 40 years and comparing the results with the conclusion drawn by analyzing sediments in the same area; assessing the distribution characteristics of the sensibility of soil erosion; computing the amount of potential soil erosion and assessing the capability of soil conservation of different types of land use; bringing forward the measures of defending soil erosion after analyzing the characteristics of soil erosion intensity, sensibility, and the capability of soil conservation and running the model to verify the effectiveness of the measures. It arrives at some conclusions as follows: (1) in the past 40 years, soil erosion in the drainage basin has experienced a process of getting more intense and then becoming slighter which accords with the results received by using sediment-analysis method. The characteristics of the distribution of soil erosion in this basin vary in different elevation, gradient, and land use type. The main driving factors are precipitation and the area of the dry land; (2) the extent of the sensibility of soil erosion in the basin are main middling and slight, and its characteristics of spatial distribution are clear and regular. Different kind of land has different erosion sensibility, and the dry land has a largest extent. It shows that the higher erosion sensibility, the more erosion amount. (3) The meadow and dry land have a largest amount of potential soil erosion, and the modulus of potential soil erosion and soil conservation decrease from woodland to meadow, dry land, and paddy field. The paddy field has the greatest capability of soil conservation and the dry land has the lowest. The dry land has the most soil erosion amount, sensibility, and the lowest capability of soil conservation among all types of land, so the key of soil erosion prevention is taking effective measures for it. After verified by running RUSLE Model, the measures of returning dry land with a high gradient to woodland and low gradient to terrace are effective.