Comparative assessment of soil erosion modelling approaches in a Himalayan watershed

Abstract

The quantitative estimate of soil erosion, in space and time, is valuable information to initiate land degradation measures at a watershed level. In this study, two models, Morgan Morgan Finney (MMF) and universal soil loss equation (USLE), were used in GIS environment to assess the soil erosion, as a function of land use/land cover, soil and topography in a mountainous watershed in the Kashmir Himalayan region, India. The two modelled soil erosion estimates were validated using the available land degradation maps of the area in order to determine their efficacy for soil erosion modelling. The results from the two models showed some similarity between the two soil erosion estimates. However, keeping in view the soil deposition being taken into consideration by MMF (47.33% of watershed area), the disagreement with the USLE soil estimates is understandable. USLE estimated 72.52% of watershed area under 0–1 kg m−2 year−1 while as the MMF model estimated only 41.27% of the watershed area in this category. In both the model results, almost equal area of the watershed has been classified with erosion > 10 kg m−2 year−1 category. Based on the model validation with the available land degradation data, the USLE estimates of soil erosion were found more reliable because of the good correlation with the land degradation maps. The erosion estimates worked out in this study, particularly the categories under very high, high, severe and very severe eroded areas, shall go a long way in framing up the strategies for mitigation and control of soil erosion in the mountainous Himalayan watershed.