Modeling hydrological characteristics based on land use/land cover and climate changes in Muga watershed, Abay River Basin, Ethiopia

Land use/land cover changes and climate change can have profound effects on hydrology within watersheds. The Soil and Water Assessment Tool model was used to evaluate the individual and combined impacts of land use/land cover and climate on the hydrology of the Muga watershed. The model was calibrated and validated based on observed streamflow data. The calibrated and validated model demonstrated good performance, as indicated by Nash Sutcliff Efficiency values of 0.79 for calibration and 0.82 for validation. Similarly, the Percentage of Bias values of 8.2% for calibration and 9.3% for validation indicate a small overall bias in the model's predictions. According to the findings of this study, there is an overall increase in surface runoff (15.78% in 2022 and 15.28% in 2038) and water yield (1.22% in 2022; 0.83% in 2038), along with a reduction in lateral flow (8.55% in 2022; 7.0% in 2038), groundwater flow (9.21% in 2022; 10.0% in 2028), streamflow (5.8% in 2022; 3.3% in 2038), and evapotranspiration (1.54% in 2022; 0.95% in 2038), compared to the baseline year (1994). The land use/land cover changes in 2022 and projected for 2038 contributed to these alterations in hydrological parameters. The combined effect of land use/land cover and climate change on water balance is relatively higher than the impact of land use/land cover change scenario alone. The intensified rainfall contributes to the observed increase in surface runoff and water yield. Hence, the study is crucial to implementing sustainable land use practices and appropriate watershed management strategies. Climate change is a global concern affecting many landscape characteristics. Land use changes as an important variable in soil erosion are expected to change under projecting climatic scenarios. Evaluation of future soil erosion is crucial for devising appropriate interventions. Moreover, research results from such studies contribute to planning, decision-making, and policy development which could make possible sustainability of natural resources.