Spatiotemporal evaluation of precipitation and streamflow trends in the Upper Awash River Basin using multisource data (1990–2023)

In Ethiopia, it is challenging to understand long-term changes in the regional water cycle due to the quality and the accessibility of data, which are essential for effective water management. Therefore, we aim to assess the spatiotemporal trends and variability of precipitation based on in situ data from 19 rain-gauge stations and multisource auxiliary data (ERA5, Climate Hazards Group Infrared Precipitation with Stations (CHIRPS), and TerraClimate (TERRA)), and streamflow from eight stream gauges in the Upper Awash River Basin, Ethiopia, over 34 years (1990–2023). Moreover, innovative trend analysis, Mann–Kendall test, and Sen's slope were employed. Both precipitation and temperature have an impact on streamflow, which varies between 27.94 and 536.86 cumecs. Five distinct trends, including nonmonotonic positive, monotonic negative, monotonic positive, and trendless, are observed. Precipitation varies by elevation and shows divergent seasonal patterns with climate zones. ERA5 consistently outperformed with high Kling–Gupta efficiency (0.66–0.94) and correlation coefficient (CC; 0.84–0.97), low root mean square error, and minimal bias, making it ideal for basin-wide modeling. Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) performed satisfactorily well (CC = 0.63–0.98) but required calibration in semi-humid regions, while TERRA showed strong spatial variability with good performance in high-elevation areas. Our findings are crucial for planning and policymaking for adaptive water resource management, determining the best-performing data for the water budget studies, and hydrological modeling studies.