Water erosion prediction using Revised Universal Soil Loss Equation and GIS: A case study of Gorganrud Basin

Document Type: Research Paper

Authors

1 University of Payam-e-noor, Kerman, Iran.

2 Gorgan University of Agricultural Science and Natural Resources, Gorgan, Iran.

Abstract

Soil erosion and sedimentation processes can be considered as serious eco-environmental
problems. This study aimed to estimate the basin-wide erosion using the Revised Universal
Soil Loss Equation (RUSLE). The soil erosion parameters included rainfall erosivity map
generated from the rainfall data, soil erodibility extracted from the soil map, land cover and
management map produced from supervised classification of Landsat ETM+ data, and a
Digital Elevation Model (DEM) to generate the slope length and steepness factor (LS)
maps. Support practice map was assumed as 1 as there were no significant conservation
practices. Then, the six thematic layers were integrated based on RUSLE model in GIS
environment, and the spatial distribution of soil loss in the Gorganrud Basin was achieved.
The distribution of erosion risk was 42.5% for low, 30.33% for moderate, and 27.17% for
severe classes. The highest amount of erosion occurred in the northwest to northeast and
eastern regions with lithological units including loess, young terraces and alluvial deposits
and agricultural use despite the fact that LS factors in these areas were less than 10. In the
central and southern parts of the basin, in spite of the high values of LS factor (15–55),
these areas depicted low to moderate erosion potential. This is supposed to be due to the
dense forest coverage in the region that decreases the energy of rain droplets. The soil
erosion risk map can be used for rapid assessment of the effects of environmental changes
and watershed management interventions.

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