Charting the groundwater resource
Around 70% of Africa’s people depend on water stored in soil and rocks, i.e., groundwater, for their drinking water. This situation is not limited to the countryside, but is also the case in rapidly growing urban areas. Groundwater is the foundation of water security and climate resilience across the continent. This is why IWMI will be working closely with member states of the African Ministers’ Council on Water (AMCOW) to identify knowledge gaps together, and then set about filling those gaps and sharing information with key stakeholders across the continent.
For example, the Groundwater for Resilience in Africa Network (GRAN) is pulling together the Africa Groundwater Atlas, an online tool that makes it easier to access information on the groundwater resources of 51 African countries. The Atlas can be used for groundwater assessments, planning sustainable development, training programs and anything that requires open access to information on groundwater.
A paper in the highly-respected scientific journal Nature further exemplifies the kind of evidence and advice IWMI and partners can offer AMCOW and others. Most climate models predict that Africa will become drier as a result of climate change, and that has understandably prompted concern about the recharge of aquifers. Together with a large number of colleagues, we investigated long-term data series from 14 areas across sub-Saharan Africa, looking for patterns in rainfall and recharge.
Some areas were as one might expect; the level of groundwater rises and falls in sync with rainfall, at least above a certain minimum amount of rain. In others, such as the humid tropics, there is constant recharge every year, effectively independent of rainfall. A third group, mostly in arid areas, was particularly interesting; groundwater levels are not related to average rainfall over the year. Rather, sporadic intense precipitation, occurring perhaps only once in a decade, recharges the aquifers.
This information can help to plan for climate change. The first type of aquifer might deplete more rapidly if, as predicted, rainfall generally declines. The second type might not be affected by a drier climate. Importantly, the third type might not be affected by climate change over a medium-term perspective, because although total precipitation is predicted to decline with climate change, climate models also predict a greater frequency and intensity of extreme weather events, which would maintain aquifers in these arid areas.
Much remains to be done to understand patterns of groundwater use and recharge in detail. At a local scale, IWMI and partners have been working to empower concerned citizens to contribute to knowledge generation and management. A project funded by the Danish International Development Agency (Danida) is centered on the Hout catchment in the Limpopo River Basin of the Republic of South Africa. Groundwater has been a valuable resource since the 1960s supporting the livelihoods of multiple farmers, and from space, parts of the catchment can be seen as a green oasis in an otherwise arid landscape.
Local people are concerned that water use is becoming unsustainable, partly as a result of climate change. We are training citizen scientists to measure groundwater levels, streamflow and rainfall, and to upload their observations via a smartphone app. The data will help us to understand water in the Hout catchment, for example, through modelling, and return information to the community so that they can jointly decide how best to use the limited, but highly valuable, shared groundwater resources.
The Groundwater Solutions Initiative for Policy and Practice (GRIPP) partnership, led by the International Water Management Institute (IWMI), will strengthen, expand and connect current groundwater initiatives. View full list of partners.
'My Citizen Science' is an online application tool to promote citizen (volunteer)-collected water resources data from the Hout catchment, Limpopo River Basin, Republic of South Africa. The application has been built in association with IWMI, Pretoria, South Africa, as a part of the Danida-funded project Enhancing Sustainable Groundwater Use in South Africa (ESGUSA).