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The hydrogeology maps in the Africa Groundwater Atlas
The hydrogeology maps for each country in this Atlas, at 1:5 million scale, have been developed from a series of quantitative groundwater maps for Africa that were developed by the British Geological Survey (described below). Key hydrogeological information was combined to produce a single map that shows both aquifer type (based on the geological environment and groundwater flow/storage type) and aquifer productivity (relative aquifer productivity, or groundwater potential). For some countries, the maps have been modified in collaboration with the Atlas co-authors of the relevant country pages, to ensure that they represent the hydrogeology at a national scale as well as possible.
Like all maps, these hydrogeology maps of Africa are a two-dimensional representation of the complex three-dimensional geological reality. The large scale of the original map line work (1:5 million scale) means that the maps provide a country-scale overview and do not show small or local scale detail. In most cases, the maps show the uppermost aquifer only - if there are other aquifers at depth, these are not shown. In some cases, where a major aquifer is overlain by unconsolidated sediments that don't form a major aquifer, the overlying sediments are not shown on the hydrogeology maps.
You can read more detail about the information shown by these maps, and how they were developed, on the Developing the Africa Groundwater Atlas Hydrogeology Map page.
Quantitative groundwater maps for Africa
The hydrogeology maps in this Atlas are based on Africa-wide maps that were originally developed by the British Geological Survey as part of the Quantitative Groundwater Maps for Africa project (MacDonald et al., 2010, 2012).
This project produced three new groundwater maps for Africa, based on a geology map of Africa at 1:5 million scale (Persits et al., 2002, Furon and Lombard 1964). The three groundwater maps are:
- Groundwater (aquifer) productivity
- Groundwater storage
- Depth to groundwater
These three maps can be freely downloaded in digital form as a 5 km resolution grid (xyz tab-delimited text file), which can be used in GIS. They are also available as high resolution PDF files. Download the Africa groundwater maps here.
More information on these Africa-wide maps can be seen in these documents:
MacDonald, A M, Bonsor, H C, Ó Dochartaigh, B É, and Taylor, R G. 2012. Quantitative maps of groundwater resources in Africa. Environmental Research Letters, 7 (2), 024009. 10.1088/1748-9326/7/2/024009
MacDonald, A M, Ó Dochartaigh, B É, Bonsor, H C, Davies, J, and Key, R. 2010. Developing quantitative aquifer maps for Africa. British Geological Survey Internal Report, IR/10/103.
Other hydrogeology maps for Africa
The World-wide Hydrogeological Mapping and Assessment Programme (WHYMAP) was launched in 2000 to provide summary information about global groundwater resources.
Several global and continental scale maps related to groundwater resources, groundwater basins, large aquifer systems, and transboundary aquifers are available to download (as pdf or image files) from the WHYMAP website.
These maps include a groundwater resources map of Africa; and scans of national hydrogeological maps across Africa through the WHYMIS application. These national maps are also indexed in the Africa Groundwater Literature Archive.
In 2008, BRGM published a hydrogeological map of Africa at a scale of 1:10 Million, the first of its kind at this scale. The map is produced as a hard copy and in GIS form. It was developed by combining two categories of data: groundwater reservoir (or aquifer) type; and the proportion of precipitation available to recharge to aquifers. BRGM used extensive data to develop the map, which distinguishes eleven major hydrographic units.
This map, at 1:5 Million scale, is not available digitally but is described in the report by Gilbrich and Struckmeier (2014).
Gilbrich, W H, and Struckmeier, W F. 2014. 50 Years of Hydro(geo)logical Mapping Activities. German Federal Institute for Geosciences and Natural Resources (BGR) and UNESCO International Hydrological Programme (UNESCO-IHP).