Assessment of soil erosion risk using RUSLE model, SATEEC system, remote sensing, and GIS techniques: a case study of Navroud watershed

Soil erosion is a major environmental threat to soil health, natural resources, and sustainable agriculture. Appropriate knowledge of dynamic factors affecting soil erosion is crucial for effective decision-making in watershed management and soil conservation practice. The present study aimed to assess the spatial-temporal distribution of annual soil loss (SL) and sediment yield (SY) in the Navroud watershed from the years 2000 to 2018 using remotely-sensed data, GIS-integrated RUSLE Model, and the GIS-based SATEEEC model. For this purpose, models' factors including rainfall erosivity factor (R), crop management factor (C), soil erodibility factor (K), and topographic factor (LS) were prepared. In addition, to boost the performance of the models, the R factor was modified by applying the effect of the snowmelt-runoff erosivity factor (SR). Long-term suspended sediment load records were used to validate the models' results at the outlet of the watershed. RUSLE model showed that mean annual SL rates in the Navroud basin ranged from 0 to over 100 ton ha(-1) year(-1) with average values of 5.39 and 14.95 ton ha(-1) year(-1) using the R factor and total rainfall-runoff erosivity (TR) factor as the sum of R and SR factors, respectively. However, for the SATEEC model, SL ranged from 0 to 144 and 0 to 461 with slightly higher average values of 6.2, and 16.76 ton ha(-1) year(-1) using the R factor and TR factor, respectively. In general, the performance of the RUSLE and SATEEC models was low (R-2 = 0.39-0.44, NSE = - 0.05, 0.15) when the R factor was used as the only erosive factor in simulating SL. However, a notably better estimation of SL and SY was observed when the TR factor was used instead of the R factor (R-2 = 0.77-0.75, NSE = 0.33-0.36). It can be concluded that RUSLE showed slightly better results than SATEEC in the Navroud watershed, and also the use of the SR factor in calculating the erosive factor has led to a notable improvement in the models' simulation. In conclusion, these findings highlight not only the need to consider the SR factor in the models' simulation, especially in mountainous regions but these results can also assist in the implementation of effective conservation practices to reduce soil erosion risk in the Navroud watershed.