A modeling approach for evaluating and predicting the impacts of land use land cover changes on groundwater recharge in Walga Watershed, Upper Omo Basin, Central Ethiopia
Barsisa Tola, Gaddissa Deyassa
Abstract
Walga watershed, Upper Omo basin, Ethiopia (2349 km2). This research aimed to understand and predict the impacts of LULC changes on groundwater recharge in Walga watershed. Thus, the historical LULC changes in Walga watershed was assessed from Landsat: 4–5 TM, 7 ETM + and 8 OLI-TIRS (1990, 2006, and 2021), through Hybrid classification of unsupervised and supervised scheme using Erdas Image 2015, while future LULC was predicted using CA–Markov chain analysis approach in QGIS-MOLUSCE plugin. The LULC change impact scenarios on groundwater recharge was assessed using SWAT model. The evaluation of LULC changes pointed out that Walga watershed has undergone high intensity of LULC changes (1990–2021) due to anthropogenic activities and predicted to instantly change in the coming (2021–2035). The hydrological assessments indicate that groundwater recharge was declined over the last three decades by 20.84 mm and predicted to decline in future (2021–2035) by 6.17 mm. This implies that the declined recharge was linked to LULC changes over time with deforestation and agricultural land expansion. This means due to changes in agriculture (+26.3 %, +15.4 %), mixed forest (−3.7, −2.3 %), rangelands (−23.8 %, −8.8 %), grazing land (−2.6 %, −2.0 %), and urban (+1.14 %, +0.46 %) during (1990–2021) and (2021–2035). These outcomes provide baseline information for decision makers concerning LULC and groundwater for better planning and management strategies in the watershed.