Assessing Soil Erosion Risk in Nepal’s Mountain Watershed using the
Revised Morgan-Morgan Finney (RMMF) Model and GIS Analysis
Abstract
Soil erosion represents a significant environmental challenge,
threatening natural resources and diminishing soil productivity and
quality. In Nepal, this issue is exacerbated by both natural factors,
such as excessive rainfall, weak geology, and earthquakes, and human
activities, including deforestation, overgrazing, intensive agriculture,
and poorly planned infrastructure construction. This research was
conducted in the Manahari Khola Sub-watershed of the Makwanpur district.
The primary aim was to evaluate the extent of soil erosion under current
Land Use and Land Cover (LULC) conditions. Essential data sets,
including LULC parameters, soil properties, rainfall data, and Digital
Elevation Models (DEMs), were generated using Landsat images, FAO
guideline-based landform maps, data from the Hydrology Department, and
Google Earth. The analysis was carried out using ArcGIS 10.8 and ILWIS
3.3 Academic software. The RMMF soil erosion modeling results indicated
a range of soil erosion risks, from Very Low to Very High. Forested and
bush areas showed lower rates of soil erosion, while barren lands
exhibited significantly higher erosion rates. The erosion susceptibility
map further demonstrated that forested regions had a very low risk of
soil erosion, agricultural areas had low to moderate risk, and barren
lands faced moderate to very high susceptibility. The study underscored
the necessity for effective conservation measures, particularly in
cutting and cliff areas and barren lands, due to their high erosion
potential. Recommendations for future action include afforestation of
barren areas, implementation of conservation farming practices in
agricultural zones, and adoption of appropriate road stabilization
measures to mitigate soil erosion risks.