Impact of land use and land cover change on streamflow dynamics within the Meki River watershed of the Ethiopian Rift Valley Basin

Land use and land cover (LULC) transformations alter watershed-scale streamflow by modifying how precipitation is partitioned into surface runoff and baseflow. This study investigates spatiotemporal LULC shifts in the Meki catchment, a critical feeder to Lake Ziway, over 24 years (1996–2020). By integrating multi-temporal Landsat imagery with the soil and water assessment tool (SWAT), we quantified the volumetric response of the basin to anthropogenic modifications. Supervised classification across eight categories revealed that agricultural land expanded by 31.27%, primarily replacing natural perennial cover. The classification achieved a robust kappa coefficient (K = 0.90) and an overall accuracy of 92.95%. Hydrological modeling, optimized via the SUFI-2 algorithm, showed that these LULC transitions caused a 42.6% increase in surface runoff and a 31.9% reduction in baseflow. This imbalance, marked by a 19.21% rise in wet-season flow and a 19.3% drop in dry-season discharge, suggests that reduced infiltration has compromised groundwater recharge and increased peak-flow flashiness. These findings provide a critical evidence base for sustainable water management in the fragile Ethiopian Rift Valley.