Himalayan watersheds in Nepal record high soil erosion rates estimated using the RUSLE model and experimental erosion plots

The rising unpredictability in the food supply chain in many parts of the world is related to soil loss and poor agricultural output. The Revised Universal Soil Loss Equation (RUSLE), widely used for estimating soil loss, was applied in the western mid-hills in Nepal, with steep slopes and fragile geology. This region is at high risk for rapid soil erosion and mass wasting. To estimate soil loss, this study utilized the RUSLE model with experimental erosion plots in the Aadhikhola and Tinahukhola watersheds, capturing real-time erosion in the field. The annual soil loss for the Aadhikhola watershed is estimated at similar to 41.4 tons ha(-1) yr(-1). In contrast, in the Tinahukhola watershed, soil loss is low (similar to 24.1 tons ha(-1) yr(-1)). Although annual rainfall showed an increasing trend in both watersheds, the change in soil loss was statistically insignificant. The high erosion rates from the experimental plots in both watersheds support the model outputs. Results from the experimental plots recorded the rate of soil erosion for different land use as: irrigated agricultural land > rainfed agricultural land > forests. The trends highlight the role of human activities in enhancing soil erosion in these mountainous terrains in terms of medium to long-term perspectives. Therefore, sustainable agriculture practices in these terrains must investigate alternate ways to decrease soil erosion to support people's livelihoods.

Automated summary

The rising unpredictability in the food supply chain is related to soil loss and poor agricultural output. The Revised Universal Soil Loss Equation (RUSLE) was applied in the western mid-hills in Nepal to estimate soil loss in areas with steep slopes and fragile geology. The results showed high erosion rates in these areas, indicating the significant role of human activities in enhancing soil erosion and the need for sustainable agriculture practices.