Sang Catherine C, Olago Daniel O
Department of Environmental Planning, Sustainability and Geoinformatics, University of Eldoret, 30100 Eldoret, Kenya.
Department of Earth and Climate Sciences, Institute for Climate Change and Adaptation, University of Nairobi, 00100 Nairobi, Kenya.
Discov Water. 2025;5(1):51. doi: 10.1007/s43832-025-00251-9. Epub 2025 Jul 9.
Water insecurity, driven by urbanization, population growth, land use and climate change, poses a global challenge. This study examines water supply and demand trends in the Mbagathi-Stony Athi sub-catchments, highlighting urbanization's impact in a semi-arid context. Using GIS, and the WEAP model, various scenarios were simulated. Results show annual rainfall increased insignificantly ( = 0.61) from 1981 to 2019. By 2063, rainfall is projected to rise by 12.43% (RCP 4.5) and 21.02% (RCP 8.5). Mean temperature increased by 0.88 °C (1981-2019) and is projected to rise by 1.70 °C (RCP 4.5) and 1.75 °C (RCP 8.5) by 2063. Land use analysis (2000-2019) showed a 53.67% increase in built-up areas and a 99.32% decline in wetlands. Between 2000 and 2019, the annual supply, demand, and unmet demand increased by 171.64%, 147.56%, and 73%, respectively. Land use changes between 2000 and 2019, particularly the increase in shrublands and decline in bare land, contributed to a 25.51% decrease in surface runoff and a 3.55% rise in total annual evapotranspiration. Future projections indicate surface runoff decreases of up to 4.47% under RCP 4.5 and increases of 9.38% under RCP 8.5. Potential evapotranspiration is projected to rise by 23.39% (reference), 16.44% (RCP 4.5), and 11.19% (RCP 8.5). Water demand will increase across all scenarios, peaking at 184% under high urbanization, while unmet demand will rise by up to 162.47% under irrigation expansion. Water scarcity is expected to worsen due to climate change, population growth, and land use shifts. These findings inform sustainable water resource management in development corridors.
由城市化、人口增长、土地利用和气候变化导致的水资源不安全构成了一项全球性挑战。本研究考察了姆巴加蒂-斯托尼阿西子流域的供水和需求趋势，突出了城市化在半干旱环境中的影响。利用地理信息系统（GIS）和水资源评价与规划（WEAP）模型，模拟了各种情景。结果显示，1981年至2019年期间年降雨量增长不显著（=0.61）。到2063年，预计降雨量将分别上升12.43%（代表性浓度路径4.5）和21.02%（代表性浓度路径8.5）。平均温度在1981年至2019年期间上升了0.88摄氏度，预计到2063年将分别上升1.70摄氏度（代表性浓度路径4.5）和1.75摄氏度（代表性浓度路径8.5）。土地利用分析（2000年至2019年）显示建成区面积增加了53.67%，湿地面积减少了99.32%。2000年至2019年期间，年供水量、需求量和未满足的需求量分别增加了171.64%、147.56%和73%。2000年至2019年期间的土地利用变化，特别是灌丛地增加和裸地减少，导致地表径流量减少了25.51%，年总蒸发散量增加了3.55%。未来预测表明，在代表性浓度路径4.5下地表径流量最多减少4.47%，在代表性浓度路径8.5下增加9.38%。潜在蒸发散预计将分别上升23.39%（参考值）、16.44%（代表性浓度路径4.5）和11.19%（代表性浓度路径8.5）。在所有情景下，需水量都将增加，在高度城市化情况下达到峰值184%，而在灌溉扩张情况下未满足的需求量将上升高达162.47%。由于气候变化、人口增长和土地利用变化，预计水资源短缺情况将恶化。这些研究结果为发展走廊的可持续水资源管理提供了参考。
