Hydrological responses to historical and predicted land use/land cover changes in the Welmel watershed, Genale Dawa Basin, Ethiopia: Implications for water resource management

Study region: Welmel watershed, Genale-Dawa Basin, Ethiopia. Study focus: This study aimed to analyze the hydrological impacts of land use/land cover (LULC) changes in the Welmel watershed for 1990-2020 and to predict the LULC change impact on the hydrological status in the year 2050. The hybrid land use classification technique for classifying Landsat images; Cellular-Automata Markov (CA-Markov) for prediction of the 2035 and 2050 LULC; and the Soil and Water Assessment Tool (SWAT) for hydrological modeling were employed in the analyses. New hydrological insights for the region: The findings revealed that from 1990 to 2020, significant alterations in the hydrological regime occurred due to historical LULC changes in the Welmel watershed, which are expected to continue in the 2035 and 2050 periods. Forest cover loss and expansion of agricultural areas, which occurred from 1990 to 2020, have resulted in increased annual flow (6.18%), wet seasonal flow (10.21%), and surface runoff (25.32%), and reduced dry seasonal flow (6.34%), groundwater flow (17.17%, and evapotranspiration (0.36%). The 2035 and 2050 LULC indicate further increased annual flow, wet seasonal flow, and surface runoff, and reduced dry seasonal flow, groundwater flow, and evapotranspiration. The study also stated the hydrological impacts of the LULC changes at the sub-watershed scales. More noticeable changes in hydrological components have been observed at the sub-watershed scale, mainly associated with the uneven spatial distribution of LULC changes. The findings provide valuable insights for policymakers, water resource managers, and local communities in formulating strategies to enhance water resource management practices in the Welmel watershed and similar regions. It could also be for researchers and Academia who can be benefited and it can be used to supplement global goals like Sustainable Development Goal 6 (SDG 6): ensure the availability and sustainable management of water and sanitation for all.