Geo-information-Based Soil Erosion Modeling for Sustainable Agriculture Development in Khadokhola Watershed, Nepal

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Geo-spatial technology as an emerging geo-information science was attempted to estimate the potential and actual soil loss and its correlative interpretation with land system units and land use and cover types in an agricultural watershed, Khadokhola, Eastern Region of Nepal. Among several empirical and physically based soil erosion models, widely used RKLS and Revised Universal Soil Loss Equation (RUSLE) were employed to estimate the potential and actual soil loss in the present investigation, respectively. Forty years of rainfall, topographic contour, and soil map were basically used as source of information for in-depth investigation. Khadokhola watershed originated from Chure/Siwalik range was found highly sensitive or prone to soil erosion. A total of 253.1 and 27.9 million tons soil was potentially and actually estimated annually being lost from Khadokhola watershed. Erosion rates were found highly correlated with the slope of land system units. 64.41% of the total potential soil loss was mainly contributed only by land system unit 8 with the spatial coverage of 17% of the watershed area. This unit was characterized by steeply to very steeply sloping hilly and mountainous terrain having dominant slope greater 20°. Such land system unit was also found highest proportion of soil loss among the averages. Subsequently, degraded forest was investigated contributing significantly as of 64% total potential soil loss. Agriculture as a lifeline of livelihood of rural communities, spatially concentrated in 74.31% of the watershed area, was contributing significantly as of 28% of the total potential soil loss and 65% of actual total soil loss in the study area. Similarly degraded bush land and scattered tree areas contributed 34,162 and 21,994 tons/ha/year on a potential average, respectively. Undulating erosional alluvial fan upper piedmont and steeply to very steeply sloping hilly and mountainous terrain having soil loss highest must be given higher priorities for soil conservation and optimum land use planning required for sustainable agricultural development. Lower percentage of actual soil to the potential loss indicated the fact of contribution of crop management and erosional control practice factor in reducing soil erosion in existing situation.