Detectability of rainfall characteristics over a mountain river basin in the Himalayan region from 2000 to 2015 using ground- and satellite-based products

Spatial variability in catchment processes is crucial for hydrologic and water resources planning and management. The spatial density of ground-based rain gauge (GRG) observations is often limited. These limitations are more pronounced in the Himalayan region. The rainfall variability is one of the primary factors affecting the water-energy cycle and is often poorly captured by the GRG observations in mountain terrain. This study evaluates the applicability of four satellite-based products (i.e., CHIRPS, MSWEP, PERSIANN, and TMPA) in capturing the rainfall characteristics across a mountain river basin in the Himalayan region. We used rainfall observations from 44 GRG locations located at different physiographic and hydroclimatic areas as a reference for systematic comparison. The comparison was able to discriminate and highlight the benefits and pitfalls of selected satellite-based rainfall estimates (SREs) and rank them based on performance metrics for rugged topography. Monotonic trends based on both ground- and satellite-based products were computed. This study finds that SREs did not well capture short-duration rainfall extremes. Different SREs exhibit a different level of performance (under- to overestimation) for both rainfall frequency and amount. A general tendency of the south to north (S–N) decreasing rainfall amount and their temporal variations are well captured in the study area by the SREs. This study reinforces the idea that several SREs are applicable for water balance and hydrologic regime analysis with local bias correction for analyzing hydroclimatic extremes.