Surface Runoff and Watershed Yield to Increase Due to Climate Change: Implications for Water Resources Management in Water-Stressed Kibwezi Catchment in Kenya
Year: 2025
Type: preprint
Abstract: Global climate change poses a significant challenge to ecosystems and human livelihoods, with the Kibwezi watershed already facing severe land degradation and water scarcity. This study applied the Soil and Water Assessment Tool Plus (SWAT+) to assess the impacts of climate change on surface runoff and water yield for near- (2010-2039), mid- (2040-2069) and end-century (2070-2100) periods, relative to a 1972-2005 baseline. Climate projections were derived from three Regional Circulation Models (RACMO22T, RCA4 and CLMcom-CCLM) under RCP 4.5 and RCP 8.5 scenarios. Model calibration and validation against evapotranspiration data in 2010-2018 achieved good performance (NSE = 0.76 and 0.76, and R 2 = 0.87 and 0.79) for calibration and validation, respectively. Results show precipitation increases of 44.1-619.9% (RCP 4.5) and 50.1-954.7%, under RCP 8.5 during 2010-2100, while mean temperatures rise by 1.3-2.8 °C and 1.4-5.1 °C respectively. Seasonal projections indicate reduced precipitation in March-May (MAM), with significant increases in October-December (OND) and January-February (JF) and stability in June-September (JJAS). Surface runoff is projected to rise by 44.1-619.9% and 50.1-954.7% under RCP 4.5 and 8.5 respectively, with corresponding water yield increases of 43.4-610.3% and 48.9-937.5% during the 2010-2100 period. Monthly and seasonal patterns indicate significant increases during JF and OND, declines in MAM and little change in JJAS. These findings highlight the potential for intensified hydrological extremes in the Kibwezi watershed in the century, underscoring the need for targeted climate adaptation and water resource management strategies in dryland regions.
Language: English
Subfield: Water Science and Technology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4414870950