Spatiotemporal variability in rainfall erosivity over Eastern India: Historical trend and future projection

Abstract

The spatiotemporal variability in annual rainfall and rainfall erosivity (R factor) is a crucial factor in assessing seasonal soil erosion dynamics and regional water resource management, since it has a substantial impact on complex interactions involving the water, soil, and surroundings under the variable climate regime of Eastern India. We analyzed the daily historical rainfall dataset received from India Meteorological Department (IMD; 1969-2022) across five meteorological subdivisions: Arunachal Pradesh (AP), Assam-Meghalaya (AM), Nagaland-Manipur-Mizoram-Tripura (NMMT), Sub-Himalayan West Bengal and Sikkim (SHWBS), and Gangetic West Bengal (GWB) of the Eastern India. Sub-district level projections of the downscaled bias corrected eight CMIP5 and five CMIP6 output on future global climate model projections was compared in Mid Future (MF) (2040-2069) and Far Future (FF) (2070-2099) timescale using the CORDEX-SA framework. Significant uncertainties existed in model simulations when validated against historical observations. In contrast to the observed spatiotemporal variability in declining in both annual rainfall and R factor over past five decades in IMD ground observations, the variable rising trend was evident particularly under high carbon scenarios of CMIP-6 over AP and AM subdivision in FF time scale. Thus, our finding emphasized the rising risk of soil erosion and shifts in hydrological cycle, which may have a negative impact on local agro-ecosystems. The projected rise in rainfall erosivity suggests that rainfall may increase kinetic energy, increasing the risk of soil erosion and anticipate future climate impacts towards the need to set up future research priorities in soil water conservation research, adaptation of climate resilient technologies and water resource management planning for different stakeholders involved in the agroecosystem research at Eastern India region.