Quantitative Research on Gully Erosion and Sedimentation using Rain Erosion Indices, Morphometry and Linear Regression in the Harzand Chai Watershed

Due to the significant expansion of surface structures and geology sensitive to linear erosion factors and severe human intervention, moaterosion is one of the important factors in the loss of surface soils in the basin. Due to the importance of the issue of gully erosion in the basin, 35 samples of gully were selected in field work and some of their dimensions such as length, width, depth of the average slope of the gully were morphometric. Then, the correlation relationships of the parameters were determined through linear regression and their effects were analyzed. In order to determine the susceptibility of the basin to linear erosion, especially gully. Also soil moisture fluctuation (Ws) and hydrothermal coefficient (ET) indices as well as pH and electrical conductivity (Ec) of the basin soils were determined after sampling. Values ​​of hydrothermal coefficient of 2.524, (pH) and electrical conductivity of the samples between 6.3 and 8.2, respectively, indicate the susceptibility of soils to linear erosion. In total, the average rain erosion of the basin in terms of tons per hectare per year according to the results of the above formulas was 201.05 ton. Hec.y and the total annual soil erosion in the basin was estimated at 41121525 tons and 291 tons per hectare. The results show high rate of soil erosion and development of gully in the basin. Ultimately some approaches for decreasing and controlling of soil and gully erosion are suggested.