Estimation of soil erosion considering soil loss tolerance in karst area

Abstract. The prediction of soil erosion is critical to regional ecological assessment and sustainable development. However, due to the geological background of the karst area, the soil holding capacity is very limited, so it is necessary to consider the allowable loss of soil. Here we took thermodynamic dissolution model of carbonate rocks and the lithological characteristics to estimate soil loss tolerance, and corrected and quantitatively evaluated the soil erosion. Major findings are as follows: (1) The soil loss tolerance of homogenous carbonate rocks is 31.10 t · ha · yr⁻¹, carbonate rock intercalated with clastic rocks is 120.81 t · ha · yr⁻¹, carbonate/clastic rock alternations is 282.55 t · h · yr⁻¹, and clastic rock is 500 t · ha · yr⁻¹. (2) After the correction of the soil loss tolerance, the average annual amount of soil loss in the study area is 3.08 t · ha · yr⁻¹, which is 41.12 % of the model. The predicted value of soil erosion is nearly the same as the observed value after modification. (3) It is necessary to reconsider the risk assessment model of soil erosion applicable to karst areas. This paper proposes an idea to estimate soil erosion based on the allowable loss of soil, which is more scientifically and accurately to reflect the soil erosion status of the study area compared with the traditional way. This study provides a corresponding reference for the formulation of soil and water conservation policies in China and the world's karst regions.