Assessment of soil erosion on hillslopes (a case study carried out in the Ashan drainage basin, Iran)

The objective of this study is to determine the rate of soil erosion on slopes of differing steepness and its effects on agricultural land and pastures in the drainage basin around Ashan. Exogenous factors like water and wind and endogenous elements such as erodibility of the soil have key roles in erosion and the results of this study will help in the management of soil and soil conservation programs. Soil erosion in the drainage basin around Ashan has accelerated and because of this it is important to determine the erodibility of the soil. In this study, the soil on four different hill slopes was sampled and after drying, soil size distribution and soil texture and the organic content of forty samples, and the k-factor (erodibility) using the USLE equation, were determined. According to the results of the ANOVA test there are strong relationships between the variables, which is illustrated by box plots. The results indicate that erodibility is significantly (p < 0.05) associated with the type of land use and landforms. The highest levels of erosion were recorded on the back-slope and the least at the summit and on the toe-slope. Discriminant function analysis was used to determine the discriminatory power of the erodibility factor associated with the different uses of land and landform components. According to the DFA results, the K factors indicate the use of the land and landforms were the most significant factors, with significances of 0.000 and 0.002, respectively.