Evaluating The Impacts Of Land Use And Climate Variability On Water Availability In Hargeisa Watershed, Somaliland

Abstract

Hargeisa, Somaliland, faces a critical water crisis driven by rapid urbanization and a volatile climate. This study provides the first comprehensive hydrological assessment for the region, aiming to quantify the impacts of historical land use change (2000–2024) and past climate patterns (1995–2024) on water availability, and to identify the resulting socio economic impacts on the community. To overcome the challenge of an ungauged watershed, a regionalization approach was employed using the Soil and Water Assessment Tool (SWAT+). The model was successfully calibrated and validated against a physically similar gauged watershed, achieving satisfactory performance (Calibration: R²=0.55, NSE=0.52; Validation: R²=0.53, NSE=0.50). This successful validation provided a scientifically sound foundation for quantifying the drivers of water scarcity. The climate analysis revealed a statistically significant warming trend (Tmax increased by 0.037°C/year and Tmin by 0.025°C/year), while precipitation showed high inter-annual variability but no significant long-term trend. The study integrated these hydrological simulations with an analysis of satellite-derived land use maps and socio-economic data from a survey of 134 residents. The findings reveal a profound landscape transformation: fueled by population growth, urban areas expanded by 377%, primarily converting natural grasslands. Hydrological simulations show this has critically impaired the watershed's ability to store water, increasing surface runoff by 24.1% while reducing groundwater percolation by 25%. This provides a direct scientific explanation for the hardship reported by 75% of residents, who find their water supply insufficient. The study concludes that Hargeisa’s water crisis is a direct consequence of uncontrolled urban expansion, a condition significantly worsened by the region’s inherent climate variability. This research provides a crucial, data-driven foundation for policy, highlighting the urgent need for integrated water management strategies, such as protecting groundwater recharge zones and implementing urban rainwater harvesting, to ensure Hargeisa's future water security.