Published in Scientific Papers. Series A. Agronomy, Vol. LXI, Issue 1
Written by Farrokh ASADZADEH, Maryam RAHMATI, Hossein ASGARZADEH
Soil erosion by water is a serious environmental problem all over the world, particularly in semi-arid regions like Iran, where agricultural water quality and productivity potential of soils have been decreased as a direct consequence of this process. Therefore, the development of a model assessing soil erosion potential and proportional risk maps, would help to protect soil and water resources. Among the empirical models, Universal Soil Loss Equation (USLE) is a widely accepted model developed for soil erosion prediction. The aim of this study was to assess erosion risk by integrating the USLE model and GIS techniques in Roze-Chay catchment, northwest Iran. The map of the USLE factors was produced as follow: rainfall erosivity factor (R) map was interpolated from data point taken from the meteorological stations; Soil erodibility factor (K) map was created by determining the particle size distribution and organic carbon of the 98 soil samples from the study area; Topographic factor (LS) was derived from digital elevation model (DEM); Croppingmanagement factor (C) was computed from NDVI values derived from Landsat-TM data. Assuming no erosion control practices in the catchment, Conservation practice factor (P) was set to be a unit, in calculations. The results showed that the annual average soil loss for the Roze-Chay catchment was 57 Mg.ha−1.ya−1 in 2015. The erosion risk map showed that, 33.6% of the total area has a low erosion risk with annual average soil loss of less than 10 Mg.ha−1.ya−1, but the area of 265 km2 (≈ 59%) in the catchment showed high to highly severe erosion risk, which should be protect by appropriate conservation practices. The high erosion risk of the catchment can be related to the topography and low levels of the vegetation cover. The developed soil erosion risk map can be used to highlight the erosion risk areas and therefore, assist the farmers and decision makers in implementing suitable conservation program to control soil erosion.
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