Continental hydrogeological maps of Africa

Africa Groundwater Atlas >> Resource pages >> Groundwater and Hydrogeological Maps of Africa >> List of National Scale Groundwater Maps in Africa

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This page provides information on groundwater and hydrogeological maps that cover the whole continent of Africa. Here are two lists providing summary information, first on continental scale maps that cover Africa alone, and then on global scale maps that include Africa. Below this are more details of selected key maps. The maps are all listed in reverse order of age, with newest maps first.

If you know of maps that aren't described here but should be, please let us know! Email us: AfricaGWAtlas@bgs.ac.uk

List of Maps covering Africa alone

This lists maps that cover the whole continent of Africa, but no other area. They are listed in reverse order of age.

Map Title	Date	Scale	Editors	Publishing Organisation	Format	Where to find
Groundwater resources map of Africa	2018			BGR / WHYMAP	Paper , pdf	Scanned image, with marginalia, viewable online
Transboundary aquifers of Africa	2018			IGRAC and UNESCO-IHP	GIS; pdf	Available to view in Online map portal; pdf
Groundwater (aquifer) productivity for Africa	2012	nominal 1:20 million	MacDonald et al	BGS	xyz tab-delimited text file (easily convertible to raster/grid in GIS)	Download digital map
Groundwater storage for Africa	2012	nominal 1:20 million	MacDonald et al	BGS	xyz tab-delimited text file (easily convertible to raster/grid in GIS)	Download digital map
Depth to groundwater for Africa	2012	nominal 1:20 million	MacDonald et al	BGS	xyz tab-delimited text file (easily convertible to raster/grid in GIS)	Download digital map
Groundwater resources map of Africa	2008			WHYMAP	Scanned pdf map	Scanned pdf map
Carte hydrogeologique de l’Afrique	2008	1:10 million	Jean Jaques Seguin et al	BRGM		Project webpage
Hydrogeological map of Africa	1992	1:5 million	Safar Zitoun, M. & Nouiouat, A.C	Organisation Africaine de Cartographie et de Télédétection (OACT)		Scanned image available to view in WHYMAP/WHYMIS portal
Major Hydrogeological Formations (after Geological Map of Africa, 1:5,000,000)	1988	1:5 million		United Nations		Scanned image available to view in WHYMAP/WHYMIS portal

List of Maps of the World that include Africa

This lists global maps that include Africa. They are listed in reverse order of age.

Map Title	Date	Scale	Editors	Publishing Organisation	Format	Where to find
World Karst Aquifer Map	2017			WHYMAP	Vector shapefile; webmap service; view online; pdf poster; printed map	Download shapefile or poster pdf; web map service; view online on WHYMAP Viewer; for a printed copy contact whymap@bgr.de
Global transboundary aquifer (TBA) maps	2009, 2012, 2014, 2015, 2017			IGRAC and UNESCO-IHP	Shapefile; view online; printed map on poster	IGRAC online portal
Global Groundwater vulnerability to floods & droughts	2015	1: 25 million		WHYMAP	Vector shapefile; webmap service; view online; pdf poster; printed map	Download shapefile or poster pdf; web map service; view online on WHYMAP Viewer; for a printed copy contact whymap@bgr.de
Groundwater and river basins of the world	2012			WHYMAP	Vector shapefile; webmap service; view online; pdf poster; printed map	Download shapefile or poster pdf; web map service; view online on WHYMAP Viewer; for a printed copy contact whymap@bgr.de
Groundwater resources of the world	2008	1:25 million & 1:40 million		WHYMAP	Vector shapefile; webmap service; view online; pdf poster; printed map	Download shapefile or poster pdf; web map service; view online on WHYMAP Viewer or IGRAC online portal; for a printed copy contact whymap@bgr.de

Details of selected continental scale maps of Africa

Groundwater Resources Map of Africa

BGR/UNESCO. 2018. Groundwater Resources Map of Africa. 1:12,500,000. BGR Hannover / UNESCO Paris.

What the map shows

The map shows the current status on groundwater resources mapping in Africa, and is presented with accompanying marginalia including hydrogeological cross sections, transboundary aquifer maps, and information from regional hydrogeological studies.

The map of groundwater resources shows a background of country political borders, with a number of overlaid hydrogeological themes:

• Hydrogeological/aquifer categories. Three categories are distinguished: major groundwater basins; areas with complex hydrogeological structure; areas with local and shallow aquifers.
• Recharge zones. Five zones are distinguished: very high, high, medium, low and very low, ranging from over 300 mm/year to zero.
• Special groundwater features, including known areas of saline groundwater, natural groundwater discharge areas in arid regions, areas of known groundwater over abstraction, and areas of groundwater mining.
• Additional hydrological features (major rivers and lakes) and selected cities including those largely dependent on groundwater

How the map was developed

The map was developed within WHYMAP (the World-wide Hydrogeological Mapping and Assessment Programme), a joint consortium programme whose objective is to summarise groundwater information on a global scale in map form. The first edition of the map was published in 2008. A second edition was produced for the 7th Africa Water Week in Libreville, Gabon, in 2018. It contains hydrogeological sections of regional aquifers as well as regional and transboundary hydrogeological surface information on the composition of geological units and their respective groundwater yield. Recharge was estimated for WHYMAP by University of Frankfurt, derived from the global hydrological model WaterGAP, the Global Runoff Data Centre (GRDC), the Global Precipitation Climatology Centre (GPCC), as well as numerous international experts and institutes. The map legend uses the International Standard Legend for Hydrogeological Maps (SLHyM) and a harmonisation methodology developed on the basis of the International Hydrogeological Map of Europe (IHME1500).

Purpose, uses and limitations of the map

The map was designed to be used as a planning tool to support the long term sustainable development and management of groundwater resources in Africa. The information on the map supports integrated management of water resources at regional level, and allows for further specific analysis, such as assessing the potential vulnerability of groundwater resources to pollution or to changes in groundwater recharge due to global climate change.

Links

An image of the 2018 edition of the printed map, with marginalia, is available to view at WHYMAP.

An image of the 2008 edition of the printed map is available to view at WHYMAP.

Quantitative Digital Groundwater Maps of Africa

British Geological Survey. 2012. Quantitative groundwater maps for Africa. 1:20,000,000 (nominal scale).

What the maps show

• Aquifer productivity: estimated relative aquifer productivity, based on typical potential yields of properly located and constructed boreholes. 6 categories ranging from Very High (>20 l/s) to Very Low (<0.1 l/s).
• Groundwater storage: 6 categories based on water depth in mm, from 0 to >50,000 mm.
• Depth to groundwater: 6 categories from <7 to >250 m.

How the maps were developed

The three maps each show a different aspect of the spatial distribution of key hydrogeological and groundwater properties:

• aquifer productivity (the potential for groundwater abstraction);
• groundwater storage; and
• depth to groundwater level.

The maps were developed in GIS and designed to be made available digitally for use in GIS. They were developed using a continental scale geological basemap at 1:5,000,000 scale originally published by UNESCO (Furon and Lombard, 1964) and digitised and made available through the USGS (Persits et al., 1997).

Some geological units were subdivided using more detailed information from regional and national geological maps and from geological studies: Precambrian basement rocks were subdivided into three categories (metasedimentary, craton and mobile belts); and sedimentary rocks were subdivided into major sedimentary basins. The resulting new digital basemap was attributed with hydrogeological information extracted from available regional, national and sub-national hydrogeological maps across Africa, which were scanned and georeferenced for use in GIS. Further detailed information used to refine this initial hydrogeological characterisation was extracted from a literature review of 250 published journal papers and reports on groundwater studies in Africa; and from a database of water borehole yields in basement rocks across Africa. Final drafts of the maps were peer reviewed by experts in African groundwater.

The hydrogeological parameters used in the maps were selected in part to reflect the availability of data. Key quantitative hydrogeological properties (including transmissivity, effective porosity and groundwater level) are scarce in much of Africa. These were subsititude by various proxy data, which have been shown to be effective surrogates in data poor areas elsewhere (e.g. Graham et al., 2009):

• typical borehole yields of effectively sited boreholes. This was interpreted as aquifer productivity, and used as surrogate for transmissivity.
• A qualitative assessment of the groundwater flow and storage characteristics of different aquifers. This was used as a proxy for effective porosity.

Interim internal maps were also produced in GIS showing aquifer flow and storage type (with 5 categories: intergranular, fracture, mixed intergranular and fracture, karst, and fracture/weathered), and aquifer saturated thickness (with 4 categories from <25 m to >250 m).

Purpose, uses and limitations of the maps

These maps were developed primarily to highlight areas in Africa that are more likely to be resilient to climate change, and areas where sufficient groundwater resources may be available to help adaptation to climate change. They were developed using the best available data at a continental scale for Africa. An assessment of confidence levels for the maps was made based on the availability and spatial distribution of the hydrogeological maps and reviewed groundwater studies from which hydrogeological information was obtained. For much of eastern and southern Africa, both good quality national hydrogeological maps and information from many individual groundwater studies are available. The lack of good quality hydrogeological maps in North and West Africa is compensated for by the availability of many individual studies, which vary from local to regional scale. In Central Africa, however, both maps and study information are scarce.

Links

The maps are available as three separate digital, GIS-enabled files that can be freely downloaded from BGS.

More information on the development of the map can be seen at BGS

and in this article:

MacDonald, A M, Bonsor, H C, Ó Dochartaigh, B E, Taylor, R G. 2012. Quantitative maps of groundwater resources in Africa. Environmental Research Letters 7, 024009.

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