SOIL EROSION ASSESSMENT BY USING REVISED MORGAN-MORGAN FINNEY (RMMF) MODEL IN A GIS FRAMEWORK IN A MOUNTAIN WATERSHED OF NEPAL

Soil erosion poses a significant environmental concern and threatens natural resources, resulting in decreased productivity and quality of soil. In Nepal, soil erosion arises from both natural factors such as excessive rainfall, weak geology, earthquakes, and human activities including deforestation, overgrazing, intensive agriculture, and unplanned infrastructure construction. A research study titled ”Soil Erosion Assessment using the Revised Morgan, Morgan Finney (RMMF) Model in a GIS Framework” was conducted in the Manahari Khola Sub-watershed of the Makwanpur district. The primary objective of the study was to evaluate the extent of soil erosion under the current Land Use and Land Cover (LULC) conditions. To perform the model, essential databases such as LULC parameters, soil parameters, rainfall parameters, and Digital Elevation Model (DEM) were generated using Landsat Images, landform maps based on FAO guidelines, data from the Hydrology Department, and Google Earth. The software tools ArcGIS 10.8 and ILWIS 3.3 Academic were utilized. The results of the RMMF soil erosion modeling indicated varying levels of soil erosion risk, ranging from Very Low to Very High. It was observed that forest and bush areas experienced lower rates of soil erosion, while barren land showed higher erosion rates. Additionally, the erosion susceptibility map illustrated that forested regions had a very low risk of soil erosion, followed by low to moderate risk in agricultural areas. Barren areas exhibited moderate to very high susceptibility to soil erosion. The study emphasized the need for proper conservation of cutting and cliff areas as well as barren land within the watershed due to their high to very high potential for soil erosion risk. Recommendations for the future included afforestation in barren areas, implementation of conservation farming practices in agricultural regions, and adoption of appropriate road stabilization measures.