An index based approach to identify and prioritize critical areas for reclamation using SWAT model

Erosion by water leads to considerable impacts on natural ecosystems and is accelerated in regions with high land use changes. In this study, through applying the K-means clustering approach on the output of SWAT model, the critical areas with respect to water erosion for Farsan Basin was prioritized for Best Management Practices (BMPs). Based on the results of SWAT model, three pollutant indicators were developed: i) contaminat Load per Unit Area Impact Index (LUAII), ii) contaminates Concentrating Impact Index (CII) and iii) the contaminat Load Impact Index (LII). The basin was divided into 26 sub-basins and according to the clustering results; the southern sub-basins which are situated on sloped areas (more than 25 degrees) were classified as high priority areas for management practice based on all indices. Sub-basins that are located in west, south west and south east have medium priority. These sub-basins are very sensitive to land use change including decreasing rangeland and increasing farming area. Among all sub-basins, those which are placed around two major streams are in stable condition because of low slope and low land use change. Finally, using the results of pollution indicators, we showed it was possible to reduce sediment and nutrient waste through implementing best management methods.