Spatio-temporal Assessment of Soil Erosion in Assam using RUSLE– GIS and Climate Change Projections under RCP 4.5

AbstractThis study presents a state-wide, decadal assessment of soil erosion in Assam using the Revised Universal Soil Loss Equation (RUSLE) integrated with Geographic Information System (GIS) tools on the Google Earth Engine (GEE) platform. Land use/land cover, soil texture, topography, and rainfall erosivity factors were combined to evaluate spatial and temporal variations in soil loss from 2013 to 2022, with extensions to future projections under the RCP 4.5 climate change scenario. Results reveal pronounced spatial heterogeneity, with persistent “very high” erosion hotspots (>40 t ha-1 yr-1) concentrated along the Brahmaputra river corridor and the southern–eastern hill districts (Karbi Anglong, Dima Hasao), while forested northern Assam remains relatively stable. Interannual variability in mean soil loss (˜5.3–9.2 t ha-1 yr-1) was closely linked to rainfall fluctuations: widespread hotspots emerged during high-rainfall years (2014 2022), whereas rain-deficit years (2018–2019 2021) showed marked contractions of severe erosion zones. The Tinsukia case study further confirmed the vulnerability of upper Assam, revealing broader high-risk extents compared to earlier localized assessments. Climate projections under RCP 4.5 indicate a steady increase in mean annual soil loss from ~19.8 t ha-1 yr-1 in 2021 to ~31.2 t ha-1 yr-1 by 2050, with progressive expansion of high and very high erosion zones across central Assam and the Brahmaputra valley. The findings highlight the strong influence of rainfall extremes, deforestation, cropland expansion, and urbanization on soil erosion in Assam. By linking observed variability with climate change projections, the study provides a robust evidence base for hotspot-focused erosion control and climate-resilient land and water management in the state.