Incorporating return period in the assessment of rainfall erosivity of India using high temporal resolution satellite precipitation product

This study presents a novel approach that combines the standard procedure of frequency analysis with the rainfall erosivity factor (R factor) calculation method from the revised universal soil loss equation (RUSLE) handbook to estimate and map the R factor for various return periods using high spatiotemporal resolution precipitation product. The 0.1 degrees 30-minute interval or half-hourly IMERG (Integrated Multi-satellitE Retrievals for Global precipitation measurement) precipitation data is utilized to generate the rainfall erosivity map of India for different return periods. Return level values of 2, 5, 10, 25, 50, and 100-year return periods are evaluated using the cumulative distribution function of best-fitted distribution, and a spatially distributed map of each return period is prepared. These maps will offer liberty to the stakeholders and policymakers to decide on the level of risk they are willing to take. Moreover, the high spatial resolution gridded data will minimize the probable error of interpolated maps in areas with a limited number of stations or no stations. In traditional practice, the average annual rainfall erosivity is considered for computing soil loss. However, this study has revealed that the average annual rainfall erosivity fell between return levels of 2 and 5-year return periods in around 94% of the studied area, highlighting the underestimation of rainfall erosivity.