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'Huge' water resource exists under Africa
Scientists say the notoriously dry continent of Africa is sitting on a vast reservoir of groundwater. They argue that the total volume of water in aquifers underground is 100 times the amount found on the surface. The team have produced the most detailed map yet of the scale and potential of this hidden resource. Writing in the journal Environmental Research Letters, they stress that large scale drilling might not be the best way of increasing water supplies. Across Africa more than 300 million people are said not to have access to safe drinking water. Demand for water is set to grow markedly in coming decades due to population growth and the need for irrigation to grow crops.
In Africa, groundwater is the major source of drinking water and its use for irrigation is forecast to increase substantially to combat growing food insecurity. Despite this, there is little quantitative information on groundwater resources in Africa, and groundwater storage is consequently omitted from assessments of freshwater availability. Here we present the first quantitative continent-wide maps of aquifer storage and potential borehole yields in Africa based on an extensive review of available maps, publications and data. We estimate total groundwater storage in Africa to be 0.66 million km3 (0.36–1.75 million km3). Not all of this groundwater storage is available for abstraction, but the estimated volume is more than 100 times estimates of annual renewable freshwater resources on Africa. Groundwater resources are unevenly distributed: the largest groundwater volumes are found in the large sedimentary aquifers in the North African countries Libya, Algeria, Egypt and Sudan. Nevertheless, for many African countries appropriately sited and constructed boreholes can support handpump abstraction (yields of 0.1–0.3 l s−1), and contain sufficient storage to sustain abstraction through inter-annual variations in recharge. The maps show further that the potential for higher yielding boreholes ( > 5 l s−1) is much more limited. Therefore, strategies for increasing irrigation or supplying water to rapidly urbanizing cities that are predicated on the widespread drilling of high yielding boreholes are likely to be unsuccessful. As groundwater is the largest and most widely distributed store of freshwater in Africa, the quantitative maps are intended to lead to more realistic assessments of water security and water stress, and to promote a more quantitative approach to mapping of groundwater resources at national and regional level.
| Contact information |
A M MacDonald, British Geological Survey, West Mains Road, Edinburgh EH9 3LA, UK // Matt McGrath , Science reporter, BBC World Service
(email: amm@bgs.ac.uk) |
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| News type | Inbrief |
| File link |
http://iopscience.iop.org/1748-9326/7/2/024009/pdf/1748-9326_7_2_024009.pdf |
| File link local |
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| Source of information | BBC News |
| Subject(s) | HYDRAULICS - HYDROLOGY , INFORMATION - COMPUTER SCIENCES , MEASUREMENTS AND INSTRUMENTATION , METHTODOLOGY - STATISTICS - DECISION AID , NATURAL MEDIUM , RISKS AND CLIMATOLOGY , TOOL TERMS |
| Relation | http://iopscience.iop.org/1748-9326/7/2/024009/article |
| Geographical coverage | Africa, Egypt, Libya,Morocco, Algeria, Tunisia, Mauritania,Sudan, |
| Working language(s) | ENGLISH |
