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Groundwater in Africa: Harnessing the hidden sea for climate adaptation.
A DFID-funded study provides new information on the extent and potential of groundwater as a way to support development and help buffer the impact of climate change.
In 2010 we commissioned a consortium led by the British Geological Survey to study the vulnerability of groundwater to climate change in Africa. The aim of the study was to improve our understanding of the twin impacts of climate change and increasing demand on groundwater resources on the continent. The study finished in 2011 and the reports are available online.
The study has produced the first set of quantitative continent wide maps of groundwater availability for Africa by utilising existing maps and studies, and undertaking targeted field studies in Nigeria, Tanzania, Uganda and Ethiopia. A paper describing the maps was published in the journal Environmental Research Letters on April 20. This paper is open access and the full text can be downloaded.
These maps are the first of their kind for Africa and show the wide variation in groundwater resources across the continent. A key finding was that many countries usually considered water scare have large volumes of groundwater underlying them, but the poor accessibility of the groundwater means that countries still suffer from economic water scarcity.
The research indicates that for much of the populated parts of Africa it is possible to access groundwater using boreholes and handpumps for drinking water if accompanied by appropriate investigations using suitable expertise. The development of available groundwater will certainly help improve water security but the research emphasises the need for careful planning of groundwater development. However, building strategies that depend on the availability of widespread higher reliable yields from groundwater (for example for commercial irrigation) is likely to be problematic.
Resilience of the resource to climate change
The study team concluded that groundwater in Africa possesses a high resilience to climate change and should be central to adaptation strategies. Shallow groundwater in the continent has a residence time of several decades (measured by the age of the water in the aquifers) and so is a useful buffer against short-term climate variability and particularly drought.
The study also looked at the occurrence of higher yielding groundwater supplies in basement rock areas in humid Uganda and semi-arid Tanzania. The study concluded that aquifers in semi-arid environments are recharged episodically in association with extreme climate events that happen only a few times (or sometimes only once or twice) every decade and that high yielding supplies in basement rocks areas exist only in particular conditions, where alluvial sediments over the basement rocks, giving enhanced groundwater storage. This suggests that for these aquifers, the more frequent extreme events likely as a consequence of climate change may in fact not be as problematic for groundwater recharge as has previously been thought.
Detailed analysis of data on water use in Ethiopia found that both wealth and the seasonality of water access are important drivers of domestic and productive water use, probably due to higher collection times in the dry season and the labour shortages faced by poor households.
How will these findings be used?
The findings of this study are of particular use in developing policy and planning for climate change adaptation. But to achieve this, support to better management of groundwater, including improved detailed mapping, and a better understanding of resource sustainability and water quality is required at a country level. As a follow-on, we are planning to support a similar study in South Asia and groundwater also forms a central element in the design of a new water research programme being developed by RED.