Sub-Watershed wise Assessing and Prediction on Soil Erosion in Phewa Lake Using Geo-Spatial Tools

This paper assessed and predicted on soil erosion in Phewa Lake sub-watershed wise using Geo-spatial tool-based soil erosion modeling approach with LULC change detection to quantify the influence of changing LULC on erosion risk. Four LULC maps were generated for a 15-year period (1995 through 2010) at 5-year intervals to assess LULC change and to predict the projected 2020 LULC scenario. Revised Morgan, Morgan & Fenny (RMMF) soil erosion model was used and to predict soil erosion loss & erosion risk. The result of the study revealed that weighted average soil loss for the whole watershed were 19.20, 24.90, 28.50, 34.10 and 42.17 t/ha/yr for the year 1995, 2000, 2005, 2010 and predicted 2020, respectively. The result of prioritization of sub-watersheds concluded that out of 5 sub-watersheds, 2 sub-watersheds (Mid and South Flowing) are under Very high (Class I) soil conservation priority class with weighted average soil loss (> 50 t/ha/yr) predicted for the years 2010, and 2020. Andheri and Harpan sub-watersheds are categorized as High priority class (Class II, average soil loss-25 to 50 t/ha/yr.) and Medium priority class (Class-III, average soil loss-15 to 25 t/ha/yr), respectively.