Statistical evaluation of multi-satellite precipitation products: Performance, uncertainty, and sensitivity analysis against ground observations and climatic trends in the Omo-Gibe transboundary basin, Ethiopia

Study region The Omo-Gibe River Basin in south-western Ethiopia is a hydrological significant East African basin characterized by complex terrain, high climatic variability, and sparse rain-gauge coverage. These constraints increase reliance on gridded precipitation datasets, yet their catchment-scale reliability, uncertainty, and trend consistency remain insufficiently evaluated. Study focus This study evaluates five widely used satellite- and reanalysis-derived precipitation datasets (CHIRPS, PERSIANN-CDR, CFSR, ERA5, and ERA5-Land) against long-term rain-gauge observations across the Omo-Gibe River Basin (1990–2020). Station-based gridded precipitation extracted from Climate Engine was evaluated at daily, monthly, and seasonal scales using statistical (CC, RMSE, ME, Bz) and categorical (POD, FAR, CSI) metrics, with uncertainty and precipitation trends assessed using Sen’s slope and the Mann–Kendall and modified Mann–Kendall tests. New hydrological insights for the region CHIRPS showed the highest overall agreement with observations (CC up to 0.85; Bz: 0.97–1.07), while CFSR exhibited the largest biases ((Bz: 0.47–2.16). and ERA5-Land consistently outperformed ERA5. Monthly estimates were less accurate (RMSE up to 78 mm/day), though categorical scores improved seasonally. Significant positive trends were found for CHIRPS (Z = 1.8) and ERA5-Land (Z = 1.7). Precipitation uncertainty and trends were strongly controlled by topography and seasonality, highlighting the importance of terrain-specific validation for reliable hydro climatic analyses and water-resources management in data-scarce mountain basins.