Prioritizing of the Sub-Watersheds using the Soil Loss Cost Approach (A Case Study; Selj-Anbar Watershed, Iran)

Aims The present study has used results of the application of Revised Universal Soil Loss Equation (RUSLE) in integrated with the economic cost of soil loss to prioritize sub-watersheds of Selj-Anbar Watershed in Mazandaran Province, northern of Iran. Materials and Methods Overlay of five input layers of RUSLE model, viz., rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), cover and management (C) and support and conservations practices (P) factors has been done in Geographical Information system (GIS) platform for the study watershed. Then, the soil loss and sedimentation cost have assessed using soil nutrient depletion analysis. In this method, monetary value to the depleted nutrients based on the cost of purchasing an equivalent amount of used chemical fertilizer in the watershed was assigned. Findings The average soil loss and sediment rates of 4.92 and 1.98 t ha-1, respectively was obtained for the study watershed. In addition, the direct and indirect costs caused by soil loss during the five-year period in the Selj-Anbar Watershed were obtained 4.32×105 and 6.40×105 US$ which was totally equal to 10.98×105 US$. The highest (5.59×104 US$) and lowest (1.16×104 US$) annual cost of soil loss was estimated in the sub-watersheds S1-1-1 and S1-1-2, respectively. Conclusion Spatial distribution of soil loss and erosion cost could provide a basis for comprehensive and sustainable watershed management. The sub-watersheds with high soil erosion and cost rates deserve superior priority for implementation of conservation activities.