DOI: 10.26650/ijegeo.1861107 ISSN: 2148-9173

Effect of Climate Variability on Rainfall Dynamics in a River Basin: Implications for Sustainable Water Resources Utilization

Joel Aholi, Mary Makokha, Kennedy Obiero
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This study examines the influence of climate variability and land use/land cover (LULC) changes on rainfall dynamics and hydrological responses within the Zaaba River watershed in western Kenya. Long-term daily rainfall and discharge data (1991–2020) were analyzed using Mann–Kendall trend tests and Sen’s slope estimator to determine temporal variability and trends. Spatial analysis of LULC changes was conducted using Landsat imagery (2001, 2011, and 2020) through supervised classification techniques in GIS. Results indicate a slight but statistically significant increasing trend in seasonal (MAM and OND) and annual rainfall, suggesting potential increases in water availability alongside heightened flood risks. However, substantial LULC transformations were observed, including a decline in agricultural and riparian vegetation and a marked expansion of built-up areas. These changes have altered watershed hydrological processes by reducing infiltration and evapotranspiration while increasing surface runoff and river discharge variability. Correlation analysis reveals that both rainfall variability and anthropogenic land transformations signif icantly influence streamflow patterns. The combined effects of climate variability and LULC change have increased the vulnerability of water resources and agricultural systems within the basin. The study highlights the need for integrated watershed management strategies, including vegetation restoration, sustainable land use planning, and adaptive water resource management, to enhance resilience to climate variability and ensure sustainable water utilization.

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