Simulating the Influence of Rainfall Variability on Discharge in the Upper River Yala Basin, Kenya

https://doi.org/10.51867/ajernet.6.1.10

Authors

Keywords:

Annual Low Flow, Climate variability, SWAT Model, Watershed

Abstract

Climate variability is significantly altering river flows globally, increasing the risk of floods and droughts. Projections indicate both rising and declining flows across various regions, influenced by the impacts of climate variability and land use changes. Research has shown that climate change, land use, and pollution exacerbate water scarcity for half the global population, impacting ecosystems, especially in vulnerable regions. This study focuses on the Upper Yala River in Kenya, exploring climate variability's influence on discharge in various Land Use contexts using the SWAT model. Existing research highlights the significance of land use, hydrological indicators, and climate data, establishing a framework to analyze stream flow trends. The study analyzed climate and stream flow data from 1990-2020 using the SWAT model for hydrological assessment and predictions for the years 2024 to 2040 was done. The research was guided by Water Balance Theory and employed a descriptive and analytical design. Data collection included meteorological data from weather stations, hydrological data from gauging stations, and land use and land cover (LULC) data from remote sensing and satellite imagery. The Soil and Water Assessment Tool (SWAT) was used to simulate river discharge and assess the impacts of climate variability, integrating climate, land use, soil type, and topographic data. Data analysis involved descriptive statistics to summarize discharge data, correlation analysis to link rainfall variability and discharge patterns, and performance metrics like the Nash-Sutcliffe Efficiency (NSE) and Coefficient of Determination (R²) to validate the model. Statistical techniques identified long-term trends in climate and streamflow, focusing on inter-seasonal and inter-annual variations. The Upper Yala River Basin experiences significant inter-seasonal and inter-annual streamflow variations, primarily influenced by rainfall fluctuations. A strong correlation between simulated and observed discharge data for the Upper Yala River Basin was demonstrated. The mean observed discharge was 48.69 m³/s, with maximum and minimum values of 163.09 m³/s and 0.328 m³/s, and a standard deviation of 34.28 m³/s. In contrast, the simulated discharge had a mean of 53.56 m³/s, with maximum and minimum values of 174.41 m³/s and 0.360 m³/s, and a standard deviation of 37.87 m³/s. The minimal differences between the observed and simulated values underscore the model's effectiveness in accurately reflecting the impacts of rainfall variability on river flow dynamics. The study concluded that in the Upper River Yala watershed, rainfall variability accounted for 94.2% of the variations in river discharge quantity. The study recommends enhancing climate monitoring by adding weather stations and stream gauges in the basin and utilizing remote sensing for tracking land use and vegetation changes. Improved data availability from these measures will enable better discharge predictions and inform water management decisions to mitigate climate impacts on the river basin and surrounding communities.

Author Biographies

Dr. Veronica Mwikali Kiluva, Masinde Muliro University of Science and Technology, Kenya

Department of Disaster Preparedness and Engineering Management

Dr. Wekulo Saidi Fwamba, Masinde Muliro University of Science and Technology, Kenya

Department of Disaster Preparedness and Engineering Management

Dimensions

Abbas, M., Zhao, L., & Wang, Y. (2022). Perspective impact on water environment and hydrological regime owing to climate change: A review. Hydrology, 9(11), 203. https://doi.org/10.3390/hydrology9110203 DOI: https://doi.org/10.3390/hydrology9110203

Arnold, J. G., Srinivasan, R., Muttiah, R. S., & Williams, J. R. (1998). Large area hydrologic modeling and assessment: Part I. Model development. Journal of the American Water Resources Association, 34(1), 73-89. https://doi.org/10.1111/j.1752-1688.1998.tb05961.x DOI: https://doi.org/10.1111/j.1752-1688.1998.tb05961.x

Bai, Y., Zheng, H., Ouyang, Z., Zhuang, C., & Jiang, B. (2019). Impacts of land use and climate change on water-related ecosystem services in Kentucky, USA. Science of the Total Environment, 6(4), 133 https://doi.org/10.1016/j.scitotenv.2019.133640 DOI: https://doi.org/10.1016/j.scitotenv.2019.133640

Bhatti, A. Z., Farooque, A. A., Krouglicof, N., Li, Q., Peters, W., Abbas, F., & Acharya, B. (2021). An overview of climate change induced hydrological variations in Canada for irrigation strategies. Sustainability, 13(9), 4833. https://doi.org/10.3390/su13094833 DOI: https://doi.org/10.3390/su13094833

Bismark, M. B., Wilson, A. A., Mexoese, N., & Samuel, A. K. (2021). Comparing farmers' perceptions of climate variability with meteorological and remote sensing data: Implications for climate-smart agriculture technologies in Ghana. American Journal of Environmental Science and Engineering, 5(4), 104-112. https://doi.org/10.11648/j.ajese.20210504.14 DOI: https://doi.org/10.11648/j.ajese.20210504.14

Chakilu, G. G., Sándor, S., & Zoltán, T. (2020). Change in stream flow of gumara watershed, upper blue nile basin, ethiopia under representative concentration pathway climate change scenarios. Water, 12(11), 3046. https://doi.org/10.3390/w12113046 DOI: https://doi.org/10.3390/w12113046

Collins, D. B. (2020). New Zealand river hydrology under late 21st century climate change. Water, 12(8), 2175. https://doi.org/10.3390/w12082175 DOI: https://doi.org/10.3390/w12082175

Domínguez-Tuda, M., & Gutiérrez-Jurado, H. A. (2021). Global analysis of the hydrologic sensitivity to climate variability. Journal of Hydrology, 3(8), 126. https://doi.org/10.1016/j.jhydrol.2021.126720 DOI: https://doi.org/10.1016/j.jhydrol.2021.126720

Gudmundsson, L., Leonard, M., Do, H. X., Westra, S., & Seneviratne, S. I. (2019). Observed trends in global indicators of mean and extreme streamflow. Geophysical Research Letters, 46(2), 756-766. https://doi.org/10.1029/2018GL079725 DOI: https://doi.org/10.1029/2018GL079725

Intergovernmental Panel on Climate Change (IPCC). (2014). Climate change 2014: Impacts, adaptation, and vulnerability. Part A: Global and sectoral aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press.

Jared, O. O (2018). Simulation of water supply and demand in Yala (Doctoral dissertation, Masinde Muliro University of Science and Technology).

Kay, A. L. (2021). Simulation of river flow in Britain under climate change: Baseline performance and future seasonal changes. Hydrological Processes, 35(4), 141. https://doi.org/10.1002/hyp.14137 DOI: https://doi.org/10.1002/hyp.14137

Khan, A. J., Koch, M., & Tahir, A. A. (2020). Impacts of climate change on the water availability, seasonality, and extremes in the Upper Indus Basin (UIB). Sustainability, 12(4), 1283. https://doi.org/10.3390/su12041283 DOI: https://doi.org/10.3390/su12041283

Kibret, K., Seleshi, Y., & Fekadu, S. (2020). Rainfall and temperature variability influences river flow patterns in western Kenya: A case study of the Upper Yala River Basin. Water, 12(5), 1372. https://doi.org/10.3390/w12051372 DOI: https://doi.org/10.3390/w12051372

Kitheka, J. U., Mwangi, S., & Mwendwa, P. K. (2019). The effects of rainfall variability and land use/land cover change in a small tropical river basin in Kenya. International Journal of Hydrology, 3(1), 307. https://doi.org/10.15406/ijh.2019.03.00163 DOI: https://doi.org/10.15406/ijh.2019.03.00163

Li, C., & Fang, H. (2021). Assessment of climate change impacts on the streamflow for the Mun River in the Mekong Basin, Southeast Asia: Using SWAT model. Catena, 2(1), 105. https://doi.org/10.1016/j.catena.2021.105199 DOI: https://doi.org/10.1016/j.catena.2021.105199

Mastrorillo, M., Rojas, C., & Pappenberger, F. (2016). The increasing frequency and intensity of extreme rainfall events in the African Great Lakes region. Hydrology and Earth System Sciences, 20(6), 2587-2602. https://doi.org/10.5194/hess-20-2587-2016

Mendez, M., Calvo-Valverde, L. A., Imbach, P., Maathuis, B., Hein-Grigg, D., Hidalgo-Madriz, J. A., & Alvarado-Gamboa, L. F. (2022). Hydrological response of tropical catchments to climate change as modeled by the GR2M model: A case study in Costa Rica. Sustainability, 14(24), 16938. https://doi.org/10.3390/su142416938 DOI: https://doi.org/10.3390/su142416938

Njogu, J. M., & Kitheka, J. U. (2017). Correlation between river discharge and rainfall in the upper Tana Catchment. Journal of Water Resource and Protection, 9(5), 617-628. https://doi.org/10.4236/jwarp.2017.95039

Odiero, J. (2019). Simulation of rainfall surface runoff-water quality effects on surface water bodies in mid-block of Yala (Doctoral dissertation, Masinde Muliro University of Science and Technology).

Olaka, L. A., Ogutu, J. O., Said, M. Y., & Oludhe, C. (2019). Projected climatic and hydrologic changes to Lake Victoria Basin rivers under three RCP emission scenarios for 2015-2100 and impacts on the water sector. Water, 11(7), 1449. https://doi.org/10.3390/w11071449 DOI: https://doi.org/10.3390/w11071449

Olale, K., Yenesew, A., Jamnadass, R., Sila, A., & Shepherd, K. (2019). A simple field-based method for rapid wood density estimation for selected tree species in Western Kenya. Scientific African, 5(1), 149. https://doi.org/10.1016/j.sciaf.2019.e00149 DOI: https://doi.org/10.1016/j.sciaf.2019.e00149

Paul, S., & Oppelstrup, J. (2020). Hydro-meteorological processes driving solute transport in Lake Victoria. Water Science, 34(1), 18-31.

https://doi.org/10.1080/11104929.2020.1722416 DOI: https://doi.org/10.1080/11104929.2020.1722416

Peters-Lidard, C. D., Rose, K. C., Kiang, J., Strobel, M. L., Anderson, M., Byrd, A., Kolian, M., Brekke, L., & Arndt, D. (2021). Indicators of climate change impacts on the water cycle and water management. Climatic Change, 165(1-2), 11-23. https://doi.org/10.1007/s10584-021-03057-5 DOI: https://doi.org/10.1007/s10584-021-03057-5

Pokhrel, Y., Felfelani, F., Satoh, Y., Boulange, J., Burek, P., Gädeke, A., & Wada, Y. (2021). Global terrestrial water storage and drought severity under climate change. Nature Climate Change, 11(3), 226-233. https://doi.org/10.1038/s41558-020-00972-w DOI: https://doi.org/10.1038/s41558-020-00972-w

Pörtner, H. O., Roberts, D. C., Adams, H., Adler, C., Aldunce, P., Ali, E., & Ibrahim, Z. Z. (2022). Climate change 2022: Impacts, adaptation and vulnerability (p. 3056). IPCC.

Pujiono, E., Prasetyo, B. D., Setyowati, R., & Kurniadi, R. (2021, October). Vulnerability assessment of water resources to climate variability in Noelmina watershed, Timor Island, Indonesia. In IOP Conference Series: Earth and Environmental Science (Vol. 874, No. 1, p. 012007). IOP Publishing. https://doi.org/10.1088/1755-1315/874/1/012007 DOI: https://doi.org/10.1088/1755-1315/874/1/012007

Quansah, J. E., Naliaka, A. B., Fall, S., Ankumah, R., & Afandi, G. E. (2021). Assessing future impacts of climate change on streamflow within the Alabama River basin. Climate, 9(4), 55. https://doi.org/10.3390/cli9040055 DOI: https://doi.org/10.3390/cli9040055

Rickards, L., Patel, P., & Vaidya, S. (2020). Climate change impacts on water resources in India's Upper Narmada Basin: Projections and implications for water stress. Science of the Total Environment, 742, 140460. https://doi.org/10.1016/j.scitotenv.2020.140460 DOI: https://doi.org/10.1016/j.scitotenv.2020.140460

Shamir, E., Tapia-Villaseñor, E. M., Cruz-Ayala, M. B., & Megdal, S. B. (2021). A review of climate change impacts on the USA-Mexico transboundary Santa Cruz River Basin. Water, 13(10), 1390. https://doi.org/10.3390/w13101390 DOI: https://doi.org/10.3390/w13101390

Shrestha, S., Bae, D. H., Hok, P., Ghimire, S., & Pokhrel, Y. (2021). Future hydrology and hydrological extremes under climate change in Asian river basins. Scientific Reports, 11(1), 17089. https://doi.org/10.1038/s41598-021-96656-2 DOI: https://doi.org/10.1038/s41598-021-96656-2

Sok, T., Ich, I., Tes, D., Chan, R., Try, S., Song, L., Ket, P., Khem, S., & Oeurng, C. (2022). Change in Hydrological Regimes and Extremes from the Impact of Climate Change in the Largest Tributary of the Tonle Sap Lake Basin. Water, 14(9), 1426. https://doi.org/10.3390/w14091426 DOI: https://doi.org/10.3390/w14091426

Tessema, N., Kebede, A., & Yadeta, D. (2021). Modelling the effects of climate change on streamflow using climate and hydrological models: The case of the Kesem sub-basin of the Awash River basin, Ethiopia. International Journal of River Basin Management, 19(4), 469-480. https://doi.org/10.1080/15715124.2020.1755301 DOI: https://doi.org/10.1080/15715124.2020.1755301

Thompson, J. R., Gosling, S. N., Zaherpour, J., & Laizé, C. L. R. (2021). Increasing risk of ecological change to major rivers of the world with global warming. Earth's Future, 9(6), 179 https://doi.org/10.1029/2020EF001795 DOI: https://doi.org/10.1029/2021EF002048

Thornthwaite, C. W. (1948). An approach toward a rational classification of climate. Geographical Review, 38(1), 55-94.

https://doi.org/10.2307/210739 DOI: https://doi.org/10.2307/210739

World Water Program. (2019). Water and climate change: Impacts on sectors such as energy, agriculture, health, and transportation. United Nations. https://www.unwater.org/publications

Zhang, Y., Li, X., Zeng, Z., & Li, C. (2020). Impact of climate change on water resource availability: A case study of the upper Yellow River Basin. Water Resources Management, 34(5), 1417-1428.

Published

2025-01-16

How to Cite

Miima, W. A., Kiluva, V. M., & Fwamba, W. S. (2025). Simulating the Influence of Rainfall Variability on Discharge in the Upper River Yala Basin, Kenya. African Journal of Empirical Research, 6(1), 99–112. https://doi.org/10.51867/ajernet.6.1.10