Assessment Of Soil Erosion In Karst Area Based On RUSLE Model

As an extremely important carrier to economic development, land resources support the sustainable development for a country, nation and society. Currently, soil erosion, a global ecological environmental problem, is seriously posing an imminent threat on the ecological security of land use in karst area. Study on soil erosion in karst has important practical significance on the prevention of soil erosion and establishment of land use ecological patterns.On account of the application of GIS and RS, this paper took the southwest of Songzi, with the representative characteristics of karst landscape, as an example, and discussed on the applicability of two models, RUSLE model and RUSLE model with the introduction of rocky desertification factor, in the evalutaion of soil erosion in karst area. This paper, applying the conclusions of soil erosion, analyzed the characteristics of soil erosion in the southwest of Songzi. The main research content and conclusions were as follows:(1) Based on the theoretical foundation of soil erosion and rocky desertification in karst area, combined with the present situation of soil erosion and rocky desertification in study area, the factor of rocky desertification, namely ?, was introduced into RUSLE model, extracting the distribution map of six soil erosion influences and setting up a database of soil erosion factor in study area. It was proved that RUSLE model with ? has higher applicability in the quantitative analysis of soil erosion in karst, because of its higher veracity and less relative error than RUSLE model, when two soil erosion modulus of study area in 2014, respectively figured up by RUSLE model and RUSLE model with ?, were compared with actual modulus of study area in 2014.(2)The following conclusions were acquired by statistics and analysis of soil erosion modulus in the southwest of Songzi in 2014, obtained by RUSLE model with ?: the area of slight erosion reached 323.78 km2, covering 43.70% of study area; the area of mildly erosion reached 208.76 km2, covering 28.17% of study area; the area of moderate erosion reached 148.93 km2, covering 20.10% of study area; the area of intensive erosion reached 49.92 km2, covering 6.73% of study area; the area of very intensive erosion reached 9.61 km2, covering 1.30% of study area; the study area did not exist severe erosion. The average soil erosion modulus of study area was equivalent to 1849.24 t?km-2?a-1 and the intensity of soil erosion showed mildly erosion.(3)The following conclusions were obtained by analyzing the spatial distribution characteristics of soil erosion in study area, based on the result derived from RUSLE model with ?: when the range of altitudes was located between 200 meters and 600 meters, the intensity of soil erosion reached the maximum, the average soil erosion modulus showing 3251.28 t?km-2?a-1, the amount of soil erosion reaching 87.36×104 t; the most intensive soil erosion occurred when slope increased to more than 30 degrees, the average soil erosion modulus showing 5621.4 t?km-2?a-1, the amount of soil erosion reaching 13.45×104 t; the study area exists kinds of land use types, of which bare land showed the most intensive soil erosion, the average soil erosion modulus showing 4773.11 t?km-2?a-1, the amount of soil erosion reaching 8.75×104 t.