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A Review of Climate Change Impacts on Water Resources in East Africa

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Transactions of the ASABE. 58(6): 1493-1507. (doi: 10.13031/trans.58.10907) @2015
Authors:   Umesh Adhikari, A. Pouyan Nejadhashemi, Matthew R. Herman
Keywords:   Evaporation, Groundwater, Population growth, Runoff.

With one-third of the population living in drought-prone areas, Africa is considered the most vulnerable continent to climate change. This article reviews the impacts of population growth and climate change on water resources across eight East African countries, namely, Ethiopia, Kenya, Malawi, Mozambique, Rwanda, Uganda, Tanzania, and Zambia. Total population in the region is projected to exceed 800 million by 2060 and 1,150 million by 2090, compared to 286 million in 2012. Based on per capita water availability, six of the eight countries are either already water stressed or close to it. By the end of this century, per capita water availability will drop to water scarcity level in all the countries reviewed except Mozambique. ENSO is currently a dominant force that drives the climate in the region; however, future changes in this phenomenon are not well understood. Temperature projections show a 0.9°C to 3.4°C increase by the 2060s and 1.3°C to 5.5°C increase by the 2090s. However, precipitation projections are less certain in both the direction and magnitude of change, although the projections are more inclined toward positive change. For example, findings from an ensemble of models under the A2, A1B, and B1 scenarios projected a 15% reduction to a 48% increase in precipitation by 2090 in the countries studied. Projected runoff trends are largely dependent on precipitation variability and short-term rainfall distribution, which are highly uncertain in future climate scenarios. Although climate models are uncertain, runoff is generally predicted to increase in the eastern part of the region and decrease in the southern part. Glaciers and ice covers in the region are projected to disappear in next few decades; however, the impact of this disappearance on water resources in the region is predicted to be minimal. Evaporative demand is projected to increase with the increase in temperature and may reach as much as 53%, increasing water demand and moisture stress. Groundwater resources are more resilient than surface water resources; however, there is an overall lack of knowledge on how groundwater responds to climate change at the local scale. In order to mitigate the impact of climate change on water resources, water conservation and development of irrigation facilities have been recommended.

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