Detection and modeling of streamflow variations in the Abay (upper Blue Nile) basin, Ethiopia

ABSTRACT Streamflow studies support water resource management and flood/drought analysis, yet single-station or single-method approaches are often inadequate. This study analyzed trends and shifts in mean annual, annual maximum, and 7-day average minimum streamflow at 29 stations in the Abay Basin, using Mann–Kendall and Pettit tests. The Kessie watershed, showing significant change, was modeled using the HBV-Light model. Twelve years (2002–2013) were used for calibration and validation, including a 1-year warm-up. Simulations under 2002 and 2013 land use and land cover (LULC) conditions yielded average streamflows of 384.57 and 397.05 mm/year, respectively, compared to an observed average of 315.16 mm/year. LULC changes led to a 141.69 mm/year streamflow increase. These findings provide valuable insight for water management planning.