Streamflow monitoring challenges and data quality assessment in the Awash River Basin, Ethiopia

ABSTRACT Ethiopia's Awash River Basin (ARB) data scarcity and quality concerns limit effective planning and research. This study evaluated 15 streamflow gauging stations through a two-week field inspection following World Meteorological Organization (WMO) protocols, combined with observer feedback and four statistical homogeneity tests. This study also conducted analysis of streamflow trends using daily data from 15 gauging stations over the period of 1965–2015 using Mann–Kendall test and Sen's slope estimator. Field assessments revealed outdated equipment, inadequate site conditions, and low observer satisfaction, often leading to errors in water–level measurement. Homogeneity analysis showed that approximately 25%, 40%, and 33% of the stations in the Upper, Middle, and Lower Awash Basins, respectively, exhibit inhomogeneous data records, undermining long-term hydrological analyses. The study found a statistically significant increasing trend in annual streamflow in the Middle Awash Basin, while upper and lower basins showed insignificant trends. These findings highlight significant spatial variability in data reliability across the basin. The study concludes that upgrading gauging networks with telemetry, improving rating-curve updates, and enhancing observer support are urgent priorities. Strengthening institutional coordination and capacity building will be critical to ensure reliable streamflow records, thereby improving hydrological forecasting and sustainable basin-wide water resources management.