Rainfall Erosivity Dynamics in a Tropical Basin: Integration of Rain Gauge Data and Satellite-Based Precipitation

This study assessed the spatial and temporal variability of rainfall erosivity (R factor) and its implications for potential soil loss in the Velhas River Basin, Minas Gerais, Brazil. Rainfall erosivity was estimated using data from 48 rain gauge stations and precipitation derived from CHIRPS product, processed in a cloud-based environment Google Earth Engine. Between 2014 and 2024, annual R values exhibited high variability, ranging from 3,900 to more than 9,000 MJ mm ha⁻¹ h⁻¹ yr⁻¹, with peak values recorded in the wettest year (2022) and the lowest values in 2014. Potential soil loss was estimated using the RUSLE model for the years of minimum and maximum erosivity, yielding values between 0.60 and 274.17 Mg ha⁻¹ yr⁻¹. The highest soil losses occurred in areas of exposed soil and agricultural land, whereas forest formations exhibited lower rates even under high rainfall erosivity conditions. The comparison between observed and estimated datasets revealed strong spatial and statistical agreement according to the Pearson correlation coefficient (r ≈ 0.999), although CHIRPS slightly underestimated extreme values. These results demonstrate the strong potential for integrating observed and remote sensing data in hydrosedimentological analyses at the basin scale.