Editing Africa Groundwater Atlas Hydrogeology Maps

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Aquifer type is defined in terms of the hydrogeological environment, or the geological characteristics that largely control the nature of groundwater flow and storage in the aquifer. Each aquifer is defined as belonging to one of four main [[ Overview of Groundwater in Africa | '''hydrogeological environments''']] seen across Africa, with subdivisions of some of the categories (see table, below). These are a useful way of classifying aquifers, as each group has typical aquifer characteristics, and groundwater in each group behaves in similar ways.  
 
Aquifer type is defined in terms of the hydrogeological environment, or the geological characteristics that largely control the nature of groundwater flow and storage in the aquifer. Each aquifer is defined as belonging to one of four main [[ Overview of Groundwater in Africa | '''hydrogeological environments''']] seen across Africa, with subdivisions of some of the categories (see table, below). These are a useful way of classifying aquifers, as each group has typical aquifer characteristics, and groundwater in each group behaves in similar ways.  
  
A key feature of the aquifer type classification is the dominant '''aquifer flow and storage type''' - the way that groundwater flows through, and is stored in, aquifers: e.g. in weathered zones; as intergranular (or matrix) flows through pores; or through fractures; or through karstic (solution-enhanced) features.   
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The key feature of the aquifer type classification is the dominant way that groundwater flows through, and is stored in, aquifers: e.g. in weathered zones; as intergranular (or matrix) flows through pores; or through fractures; or through karstic (solution-enhanced) features.   
  
 
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The Atlas country hydrogeology maps were developed in ArcGIS by modifying and attributing a digital Africa-wide geology map at 1:5 million scale, using available hydrogeological and geological information.  
 
The Atlas country hydrogeology maps were developed in ArcGIS by modifying and attributing a digital Africa-wide geology map at 1:5 million scale, using available hydrogeological and geological information.  
  
The 1:5 million scale geology map was originally published by UNESCO (Furon and Lombard 1964), and was digitised by, and is made available through, the USGS (Persits et al., 2002). It can be accessed and downloaded in shapefile format via the USGS (details in References).
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The 1:5 million scale geology map was originally published by UNESCO (Furon and Lombard 1964), and was digitised by, and is made available through, the USGS (Persits et al., 2002). It can be accessed and downloaded in shapefile format via the USGS (details in References). The digitised geology map includes some linework defining coasts that was created using Esri© data, used with permission of Esri©.
  
The country maps are a further development of the Africa-wide [http://www.bgs.ac.uk/research/groundwater/international/africanGroundwater/maps.html '''quantitative groundwater maps'''] that were produced by BGS in 2012 ([http://nora.nerc.ac.uk/id/eprint/17892/ MacDonald et al. 2012]). The country maps use the hydrogeological understanding captured in the Africa-wide maps, and incorporate additional geological and hydrogeological information from individual countries. They reflect current understanding of national geology and hydrogeology, given the scale of the geological base map linework and the availability of geological and hydrogeological information and, where possible, they reflect different national approaches to geological and hydrogeological categorisation.
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The country maps are a further development of the Africa-wide [http://www.bgs.ac.uk/research/groundwater/international/africanGroundwater/maps.html '''quantitative groundwater maps'''] that were produced by BGS in 2012 ([http://nora.nerc.ac.uk/id/eprint/17892/ MacDonald et al. 2012]). The country maps use the hydrogeological understanding captured in the Africa-wide maps and incorporate additional geological and hydrogeological information from individual countries. They reflect the current understanding of national geology and hydrogeology, given the scale of the geological base map linework and availability of geological and hydrogeological information and, where possible, they reflect different national approaches to geological and hydrogeological categorisation.
  
Where possible, the maps have been validated in collaboration with hydrogeologists from the relevant countries who are co-authors on the relevant country pages of the Africa Groundwater Atlas (co-authors are referenced on the relevant Atlas country page and in the [http://earthwise.bgs.ac.uk/index.php/List_of_Authors List of Authors]).
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Where possible, the maps have been validated in collaboration with hydrogeologists from the relevant countries who are co-authors on the relevant country pages of the Africa Groundwater Atlas (co-authors are referenced on the relevant Atlas country page and on this page http://earthwise.bgs.ac.uk/index.php/List_of_Authors).
  
 
====Limitations of the Atlas country hydrogeology maps====
 
====Limitations of the Atlas country hydrogeology maps====
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==More Information==
 
==More Information==
 
Furon R and Lombard J. 1964. [http://unesdoc.unesco.org/images/0009/000920/092086mo.pdf Explanatory note: Geological Map of Africa (1/5,000,000) / Note explicative: carte geologique de l'Afrique (1/5,000,000)]. UNESCO and the Association for African Geological Surveys (ASGA). UNESCO, Paris, 1964.
 
  
 
MacDonald AM, and Davies J. 2000. [http://nora.nerc.ac.uk/501047/ A brief review of groundwater for rural water supply in sub-Saharan Africa]. British Geological Survey Technical Report, WC/00/033, 30pp.  
 
MacDonald AM, and Davies J. 2000. [http://nora.nerc.ac.uk/501047/ A brief review of groundwater for rural water supply in sub-Saharan Africa]. British Geological Survey Technical Report, WC/00/033, 30pp.  
  
MacDonald AM, Bonsor HC, Ó Dochartaigh BÉ and Taylor RG. 2012. [http://nora.nerc.ac.uk/17892/ Quantitative maps of groundwater resources in Africa]. Environmental Research Letters, Vol. 7(2). doi:10.1088/1748-9326/7/2/024009  
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MacDonald AM, Bonsor HC, Ó Dochartaigh BÉ and Taylor RG. 2012. Quantitative maps of groundwater resources in Africa. Environmental Research Letters, Vol. 7(2). http://nora.nerc.ac.uk/17892/ doi:10.1088/1748-9326/7/2/024009  
  
 
MacDonald AM, Ó Dochartaigh BÉ, Bonsor HC, Davies J, and Key R. 2010. [http://nora.nerc.ac.uk/501779/ Developing quantitative aquifer maps for Africa]. British Geological Survey Internal Report, IR/10/103.
 
MacDonald AM, Ó Dochartaigh BÉ, Bonsor HC, Davies J, and Key R. 2010. [http://nora.nerc.ac.uk/501779/ Developing quantitative aquifer maps for Africa]. British Geological Survey Internal Report, IR/10/103.
  
Persits F, Ahlbrandt T, Tuttle M, Charpentier R, Brownfield M, and Takahashi K. 2002. [http://pubs.usgs.gov/of/1997/ofr-97-470/OF97-470A/ Map showing geology, oil and gas fields and geologic provinces of Africa, Ver 2.0]. USGS Open File report 97-470 A.
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See also the [http://www.bgs.ac.uk/research/groundwater/international/africangroundwater/maps.html Quantitative groundwater maps for Africa] project webpage.  
 
 
USGS. 2002. [https://certmapper.cr.usgs.gov/geoportal/catalog/search/resource/details.page?uuid=%7BC7E34C48-9BD9-45C6-AD08-E549CFB3715A%7D Surficial geology of Africa (geo7_2ag)]. Shapefile for download. Accessed 11 March 2019.
 
 
 
See also the [http://www.bgs.ac.uk/research/groundwater/international/africangroundwater/maps.html '''BGS Quantitative groundwater maps for Africa'''] project webpage.  
 
  
  

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