Performance of rainfall and soil moisture satellite products on a small catchment in Central Italy

Reliable rainfall and soil moisture data is crucial to investigate hydrogeological processes at the catchment scale (runoff, soil erosion, infiltration, etc.). The present study aims to evaluate the performance of several high-resolution satellite products (IMERG GPM, SM2RAIN, Copernicus Sentinel-1 SSM1km, and SMAP L2_SM_SP) that can support hydrological studies in areas with a lack of ground-based data. The analysis was carried out in a small low permeability catchment in Central Italy (Tatarena basin), equipped with three rain gauge stations. The basin is scarcely anthropized and can be considered representative of many catchments with different soil cover, from forest to farming. The satellite rainfall products were analysed using probability plots, the double mass method, statistical tests and three categorical scores. Satellite soil moisture data were tested with the Hydrological Consistency Index, aiming to verify the consistency between soil moisture satellite data and precipitation. The results show that the IMERG GPM rainfall dataset performs better than SM2RAIN at different time scales. Despite some uncertainties, the Copernicus Sentinel-1 SSM1km proved to be the best-performing soil moisture satellite dataset. Results may be useful for using satellite data to understand runoff processes in poorly instrumented basins.