EVALUATION OF CLIMATE AND LAND USE LAND COVER CHANGE ON SURFACE WATER RESOURCES ON BALEDWEYNE WATERSHED, SHABELE RIVER BASIN, SOMALIA

Abstract

Climate change and land use/land cover (LULC) changes significantly threaten global water resources, impacting socio-economic systems. This study aimed to evaluate the effects of climate and LULC changes on the availability of surface water resources in the Baledweyne watershed. This study utilized bias-corrected outputs from three climate models (MIROC-6, MIROC-ES2L, and CMCC-ESM2) for the baseline period (1997–2022) and projected scenarios for the 2050s and 2080s under shared socio-economic pathways (SSPs) 2.6 and 8.5 LULC changes were assessed using downloaded satellite Landsat images, which were classified with the spatial analysis tool employing the supervised classification method. Classified 1997, 2008, and 2017 LULC maps were used to evaluate their impact on surface water availability. The LULC prediction was used in the Cellular Automata–Artificial Neural Network (CA–ANN) model, incorporated in the MOLUSCE plugin of QGIS. The Soil and Water Assessment Tool (SWAT) was used within the ArcGIS interface to simulate and analyze climate and LULC changes. Results indicated an increase in agricultural land by 58% and urbanization by 6.23%, alongside decreases in rangeland by 3.93% and forest land by 6.66%. The model demonstrated good performance during calibration and validation, showing strong agreement between simulated and observed streamflow, with calibration metrics of R² = 0.89, NSE = 0.83, and PBIAS values of 15 and -0.5. Under SSP1 2.6, an average rainfall increase of 22.79% was predicted for the mid-term and 8.23% for the long-term. In contrast, SSP5 8.5 projected an average rainfall increase of 23.4% in the mid-future and 2.79% in the long term. The mid-term maximum and minimum temperatures were projected to increase by 2.8°C to 2.1°C under SSP1 2.6 and by 3.1°C to 2.9°C under SSP5 8.5. In the long term, increases were projected to be 3.1°C to 1.6°C for SSP1 2.6 and 2.8°C to 1.6°C for SSP5 8.5. Additionally, the analysis indicated an increase of surface runoff by 6.38% in the mid-term and 7.52% in the long-term, while Evapotranspiration also increased by 3.05% in the mid-term and by 11.1 % in the long-term. The impact of future climate change resulted in a positive change in water availability in all seasons associated with increased precipitation. These changes can significantly affect the watershed, requiring careful management to mitigate negative impacts.