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[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Namibia
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[[Overview of Africa Groundwater Atlas | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Namibia
 
 
 
 
'''Much hydrogeological and groundwater information and many resources, including detailed maps, reports and other documents, are available for Namibia. This page provides a summary of hydrogeological understanding and groundwater resources in Namibia, and links to some of the many available resources.'''
 
 
 
[[File:CC-BY-SA_logo_88x31.png | frame | This work is licensed under a [https://creativecommons.org/licenses/by-sa/3.0/ Creative Commons Attribution-ShareAlike 3.0 Unported License]]]
 
 
 
Namibia is one of the most sparsely populated countries in Africa. Early inhabitants were San and other hunter-gatherer peoples, prior to the 14th century expansion of Bantu people into this region. In the late 19th century the region was colonised by Germany as South West Africa. Resistance to German rule was followed by the genocide of Herero and Namaqua people between 1904 and 1907, for which Germany formally apologised in 2004. South Africa took control of South West Africa after defeating German troops in World War I, and established a white minority rule similar to the South African apartheid system. In 1966, a resistance movement developed into armed struggle. In 1968 the United Nations declared South Africa’s continued occupation of Namibia illegal, but conflict continued throughout the 1970s and 80s. Independence from South Africa was achieved in 1990, after which the country saw a transition to multiparty democracy.
 
 
 
Their shared history means Namibia’s economy is closely linked to South Africa’s. A key economic activity is mining, particularly of diamonds (discovered in the early 20th century) and uranium, which contributes about 25% of export earnings, so that GDP is rather dependent on world commodity prices. Manufacturing and services, especially banking and tourism, are also important sectors. A fast-growing sector is wildlife conservancies, which support tourism and contribute to rural employment.  Although contributing less to GDP, agriculture – mostly subsistence livestock raising – is an important livelihood activity for about half the population. Agricultural land holdings are still relatively unequal, with the majority of agricultural land still owned by a minority of, mostly white, farmers carrying out mostly larger scale livestock raising, although land reform is underway.
 
 
 
Namibia is an arid country with low rainfall and high evapotranspiration. The only permanent rivers are along the northern and southern borders. Across the rest of the country surface waters are ephemeral after seasonal rainfall, with many of them dammed. Groundwater supplies most water supplies across the country, from springs and boreholes, and in rural areas also from hand dug wells. There are a number of large scale piped distribution schemes transferring both groundwater and surface water to urban areas. The first large scale desalination project in Africa was constructed in Wlotzkasbaken in 2010, to supply a uranium mine and nearby urban areas.
 
 
 
  
 
==Authors==
 
==Authors==
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'''Arnold Bittner''', SLR Environmental Consultants, Namibia
 
'''Arnold Bittner''', SLR Environmental Consultants, Namibia
  
'''Dr Kirsty Upton''', '''Brighid Ó Dochartaigh''', British Geological Survey, UK
+
'''Brighid Ó Dochartaigh''' & '''Kirsty Upton''', British Geological Survey, UK
 
 
'''Dr Imogen Bellwood-Howard''', Institute of Development Studies, UK
 
 
 
Please cite this page as: Christelis, Dierkes, Quinger, Matengu, Kirchner, Lohe, Bittner, Upton, Ó Dochartaigh and Bellwood-Howard, 2018.
 
 
 
Bibliographic reference: Christelis G, Dierkes K, Quinger M, Matengu B, Lohe C, Bittner A, Upton K, Ó Dochartaigh BÉ and Bellwood-Howard, I. 2018. Africa Groundwater Atlas: Hydrogeology of Namibia. British Geological Survey. Accessed [date you accessed the information]. http://earthwise.bgs.ac.uk/index.php/Hydrogeology_of_Namibia
 
 
 
==Terms and conditions==
 
 
 
The Africa Groundwater Atlas is hosted by the British Geological Survey (BGS) and includes information from third party sources. Your use of information provided by this website is at your own risk. If reproducing diagrams that include third party information, please cite both the Africa Groundwater Atlas and the third party sources. Please see the [[Africa Groundwater Atlas Terms of Use | Terms of use]] for more information.
 
  
 
==Geographical Setting==
 
==Geographical Setting==
  
[[File:Namibia_Political.png | right | frame | Namibia.Map developed from USGS GTOPOPO30; GADM global administrative areas; and UN Revision of World Urbanization Prospects. For more information on the map development and datasets see the [[Geography | geography resource page]].]]
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[[File:Namibia_Political.png | right | frame | Map of Namibia (For more information on the datasets used in the map see the [[Geography | geography resources section]])]]
  
 
===General===
 
===General===
 
 
{| class = "wikitable"
+
'''add wikitable'''
|-
 
|Capital city || Windhoek
 
|-
 
|Region ||  Southern Africa
 
|-
 
|Border countries || Angola, Zambia, Botswana, South Africa
 
|-
 
|Total surface area* || 824,290 km<sup>2</sup>  (82,429,000 ha)
 
|-
 
|Total population (2015)* || 2,459,000
 
|-
 
|Rural population (2015)* || 1,343,000 (55%)
 
|-
 
|Urban population (2015)* || 1,116,000 (45%)
 
|-
 
|UN Human Development Index (HDI) [highest = 1] (2014)*|| 0.6276
 
|}
 
 
 
<nowiki>*</nowiki> Source: [http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en FAO Aquastat]
 
 
 
  
 
===Climate===
 
===Climate===
  
A summary of the climate of Namibia is also available in the report [http://www.namhydro.com/downloads.html Groundwater in Namibia] (ed. Christelis & Struckmeier 2001 (2011)).
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<gallery widths="375px" heights=365px mode=nolines>
 
+
File:Namibia_ClimateZones.png |Koppen Geiger Climate Zones
[[File:Namibia_ClimateZones.png | 375x365px |Koppen Geiger Climate Zones]][[File:Namibia_ClimatePrecip.png | 375x365px |Average Annual Precipitation]][[File:Namibia_ClimateTemp.png | 375x365px |Average Temperature]]
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File:Namibia_ClimatePrecip.png |Average Annual Precipitation
 
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File:Namibia_ClimateTemp.png |Average Temperature
[[File:Namibia_pre_Monthly.png| 255x124px| Average monthly precipitation for Namibia showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall]] [[File:Namibia_tmp_Monthly.png| 255x124px| Average monthly temperature for Namibia showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature]] [[File:Namibia_pre_Qts.png | 255x124px | Quarterly precipitation over the period 1950-2012]] [[File:Namibia_pre_Mts.png|255x124px | Monthly precipitation (blue) over the period 2000-2012 compared with the long-term monthly average (red)]]
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</gallery>
  
More information on average rainfall and temperature for each of the climate zones in Namibia can be seen at the [[Climate of Namibia | Namibia climate page]].
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For further detail on these climate datasets, see the [[Climate | climate resources section]].
  
These maps and graphs were developed from the CRU TS 3.21 dataset produced by the Climatic Research Unit at the University of East Anglia, UK. For more information see the [[Climate | climate resource page]].
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A summary of the climate of Namibia is also available in the report [http://www.namhydro.com/downloads.html Groundwater in Namibia] (ed. Christelis & Struckmeier 2011).
  
 
===Surface water===
 
===Surface water===
{|
 
|-
 
|
 
Information on the hydrology of Namibia is available in the report [http://www.namhydro.com/downloads.html Groundwater in Namibia] (ed. Christelis & Struckmeier 2001 (2011)).
 
  
[[File:Namibia_Hydrology.png | frame | right |Major surface water features of Namibia. Map developed from World Wildlife Fund HydroSHEDS; Digital Chart of the World drainage; and FAO Inland Water Bodies. For more information on the map development and datasets see the [[Surface water | surface water resource page]].]]
 
  
 +
| [[File:Namibia_Hydrology.png | frame | Surface Water Map of Namibia. For more information on the datasets used in the map see the [[Surface water | surface water resources section]]]]
 
|}
 
|}
 +
 +
Information on the hydrology of Namibia is also available in the report [http://www.namhydro.com/downloads.html Groundwater in Namibia] (ed. Christelis & Struckmeier 2011).
  
 
===Soil===
 
===Soil===
 +
 
{|
 
{|
 
|-
 
|-
|
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| [[File:Namibia_soil.png | frame | Soil Map of Namibia. For more information on the datasets used in the map see the [[Soil | soil resources section]]]]
Information on soils in Namibia is also available in the report [http://www.namhydro.com/downloads.html Groundwater in Namibia] (ed. Christelis & Struckmeier 2001 (2011)).
 
 
 
 
 
[[File:Namibia_soil.png | frame | right | Soil Map of Namibia, from the European Commission Joint Research Centre: European Soil Portal. For more information on the map see the [[Soil | soil resource page]].]]
 
  
|}
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Information on soils in Namibia is also available in the report [http://www.namhydro.com/downloads.html Groundwater in Namibia] (ed. Christelis & Struckmeier 2011).
  
 
===Land cover===
 
===Land cover===
{|
 
|-
 
|
 
There are three main land cover types in Namibia: desert, savanna and woodland. The Namib Desert comprises most of the desert land cover class. Various types of savanna vegetation cover much of the country. Woodland, largely forest savanna, occurs across much of the more humid northeast and in perennial river valleys, and some ephemeral river valleys.
 
  
| [[File:Namibia_LandCover.png | frame | Land Cover Map of Namibia, from the European Space Agency GlobCover 2.3, 2009. For more information on the map see the [[Land cover | land cover resource page]].]]
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There are three main land cover types in Namibia: desert, savanna and woodland. The Namib Desert comprises most of the desert land cover class. Various types of savanna vegetation cover much of the country. Woodland, largely forest savanna, occurs across much of the more humid northeast and in perennial river valleys, and some ephemeral river valleys.  
|}
 
 
===Water statistics===
 
  
{| class = "wikitable"
+
[[File:Namibia LandCover.png]]
| || 1999 ||2000||2002||2012||2014||2015
 
|-
 
|Rural population with access to safe drinking water (%) || || ||  || || ||84.6
 
|-
 
|Urban population with access to safe drinking water (%) || || ||  || || ||98.2
 
|-
 
|Population affected by water related disease || No data || No data || No data || No data || No data || No data
 
|-
 
|Total internal renewable water resources (cubic metres/inhabitant/year) || || ||  || ||2,505 ||
 
|-
 
|Total exploitable water resources (Million cubic metres/year) || || ||  ||650|| ||
 
|-
 
|Freshwater withdrawal as % of total renewable water resources || || ||0.7063 || || ||
 
|-
 
|Total renewable groundwater (Million cubic metres/year) ||  || || || ||2,100 ||
 
|-
 
|Exploitable: Regular renewable groundwater (Million cubic metres/year) || || ||  ||300 || ||
 
|-
 
|Groundwater produced internally (Million cubic metres/year) || || ||  || ||2,100 ||
 
|-
 
|Fresh groundwater withdrawal (primary and secondary) (Million cubic metres/year) |||| ||125.3|| || ||
 
|-
 
|Groundwater: entering the country (total) (Million cubic metres/year) || No data || No data || No data || No data || No data || No data
 
|-
 
|Groundwater: leaving the country to other countries (total) (Million cubic metres/year) || No data || No data || No data || No data || No data || No data
 
|-
 
|Industrial water withdrawal (all water sources) (Million cubic metres/year) || ||14 || || || ||
 
|-
 
|Municipal water withdrawal (all water sources) (Million cubic metres/year)  || ||7.3 || || || ||
 
|-
 
|Agricultural water withdrawal (all water sources) (Million cubic metres/year) || || ||201 || || ||
 
|-
 
|Irrigation water withdrawal (all water sources) <sup>1</sup> (Million cubic metres/year) || || ||144|| || ||
 
|-
 
|Irrigation water requirement (all water sources) <sup>1</sup> (Million cubic metres/year) || || || 32 || || ||
 
|-
 
|Area of permanent crops (ha) || || ||  || ||9,000 ||
 
|-
 
|Cultivated land (arable and permanent crops) (ha) || || ||  || ||809,000 ||
 
|-
 
|Total area of country cultivated (%) || || ||  || ||0.9815 ||
 
|-
 
|Area equipped for irrigation by groundwater (ha) ||1,631 || ||  || || ||
 
|-
 
|Area equipped for irrigation by mixed surface water and groundwater (ha) || No data || No data || No data || No data || No data || No data
 
|}
 
 
 
These statistics are sourced from [http://www.fao.org/nr/water/aquastat/main/index.stm FAO Aquastat]. They are the most recent available information in the Aquastat database. More information on the derivation and interpretation of these statistics can be seen on the FAO Aquastat website.
 
 
 
Further water and related statistics can be accessed at the [http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en Aquastat Main Database].
 
 
 
<sup>1</sup> More information on [http://www.fao.org/nr/water/aquastat/water_use_agr/index.stm irrigation water use and requirement statistics]
 
  
 
==Geology==
 
==Geology==
  
An Atlas country geology map has not been developed for Namibia, as a higher resolution geology map, relevant to hydrogeology, is already available. The following summary of the geology of Namibia is based around 12 geological units that were defined according to their hydrogeological characteristics as part of the development of the Hydrogeological Map of Namibia (2001). This map, at 1 000 000 scale, was prepared as a Namibian – German technical cooperation project of the Department of Water Affairs and Forestry, Ministry of Agriculture, Water and Forestry; the Geological Survey of Namibia, Ministry of Mines and Energy; the Namibia Water Corporation and the Federal Institute for Geoscience and Natural Resources. The map is accompanied by a report [http://www.namhydro.com/downloads.html Groundwater in Namibia] (ed. Christelis & Struckmeier 2001 (2011)). More details on Namibia's hydrogeology can be found in the section below.
+
The following summary of the geology of Namibia is based around 12 geological units that were defined according to their hydrogeological characteristics as part of the development of the Hydrogeological Map of Namibia (2011). This map, at 1 000 000 scale, was prepared as a Namibian – German technical cooperation project of the Department of Water Affairs, Ministry of Agriculture, Water and Rural Development; the Geological Survey of Namibia, Ministry of Mines and Energy; the Namibia Water Corporation and the Federal Institute for Geoscience and Natural Resources. The map is accompanied by a report [http://www.namhydro.com/downloads.html Groundwater in Namibia] (ed. Christelis & Struckmeier 2011). More details on Namibia's hydrogeology can be found in the section below.  
 
 
Other geological maps are produced by the Geological Survey of Namibia. These include a simplified geological map of Namibia at 1:2 000 000 scale, a geological map of Namibia at 1:1 000 000 scale in 4 sheets (1980), and a series of geological map sheets at 1:250 000 scale covering parts of the country. More details are available from the [http://www.gsn.gov.na/mapping.htm Geological Survey of Namibia]. The 1:1 000 000 scale Geological Map of Namibia (1980) can be viewed through the [http://portal.onegeology.org/OnegeologyGlobal/ OneGeology portal].
 
 
 
More information on the geology of Namibia can be found in the References at the bottom of this page.
 
 
 
The following section provides a summary of the geology of Namibia from a hydrogeological perspective. In defining the 12 lithological (geological) units below, the main emphasis was on the groundwater potential of the rocks. Although stratigraphic relationships and spatial distribution were taken into consideration, some of the units include geological formations of more than one age or lithology.  
 
  
 +
Different geological maps are produced by the Geological Survey of Namibia. These include a simplified geological map of Namibia at 1:2 000 000 scale, a geological map of Namibia at 1:1 000 000 scale in 4 sheets, and a series of geological map sheets at 1:250 000 scale covering parts of the country. More details are available from the [http://www.gsn.gov.na/mapping.htm Geological Survey of Namibia]. Other more detailed information on the geology of Namibia can be found in the references that are given below: many of these are available through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].
  
[[File:Namibia_Geology2.png | center | frame| 700px | Hydrogeological lithological units in Namibia. The numbered units are described in the table below. Image courtesy of Christelis & Struckmeier 2001 (2011).]]
+
The following section provides a summary of the geology of Namibia from a hydrogeological perspective. In defining the 12 geological units below, the main emphasis was on the groundwater potential of the rocks. Although stratigraphic relationships and spatial distribution were taken into consideration, some of the units include geological formations of more than one age or lithology.  
  
 +
[[File:Namibia_Geology.png]]
  
 
===General Summary===
 
===General Summary===
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{| class = "wikitable"
 
{| class = "wikitable"
|+ Lithological / Hydrogeological Units
+
|+ Hydrogeological Units
|'''Unit Number'''||'''Lithological / Hydrogeological Unit'''||'''Key Formations'''||'''Period'''||'''General lithology and structure'''
+
|'''Unit Number'''||'''Hydrogeological Unit'''||'''Key Formations'''||'''Period'''||'''General lithology and structure'''
 
|-
 
|-
 
|1||Sand and gravel valley deposits||Alluvium ||Recent||Recent sedimentary infill of valleys, including the courses of some ephemeral rivers. Occasionally extensive.
 
|1||Sand and gravel valley deposits||Alluvium ||Recent||Recent sedimentary infill of valleys, including the courses of some ephemeral rivers. Occasionally extensive.
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|11||Metamorphic rocks, including quartize and marble bands, with granitic intrusions||||Neoproterozoic to Cambrian||Including many of the same formations as Unit 10, but also including granites which were intruded into Damaran metasedimentary rocks in a broad zone between Otjiwarongo and Okahandja and the coast, during mountain building processes between 650 and 450 Ma. Individual granite bodies that are too small to be shown separately on the hydrogeological map (as Unit 12) are included here with the surrounding metamorphic rocks.
 
|11||Metamorphic rocks, including quartize and marble bands, with granitic intrusions||||Neoproterozoic to Cambrian||Including many of the same formations as Unit 10, but also including granites which were intruded into Damaran metasedimentary rocks in a broad zone between Otjiwarongo and Okahandja and the coast, during mountain building processes between 650 and 450 Ma. Individual granite bodies that are too small to be shown separately on the hydrogeological map (as Unit 12) are included here with the surrounding metamorphic rocks.
 
|-
 
|-
|12||Granite, gneiss and old volcanic rocks||Epupa and Kunene complexes; Orange River Group; Vioolsdrif Suite; Elim Formation; Khoabendus Group; Rehoboth Sequence; Namaqualand Metamorphic Complex; Sinclair Sequence; Fransfontein Suite and Gamsberg Granite||Archaean to Jurassic||This unit includes a multitude of lithologies that almost covers the entire geological history of Namibia. Vaalian rocks comprise the gneisses of the Epupa Complex and the intrusives of the Kunene Complex. Early Mokolian rocks include gneisses and meta-volcanics of the old metamorphic complexes, metavolcanics of the Orange River Group, granites of the Vioolsdrif Suite, gneisses of the Elim Formation and meta-volcanics and gneisses of the Khoabendus Group. Middle to late Mokolian rocks of this unit are the meta-volcanics of the Rehoboth Sequence, the gneisses of the Namaqualand Metamorphic Complex, the meta-volcanics of the Sinclair Sequence, the granites of the Fransfontein Suite, as well as the younger granites, for example the Gamsberg Granite. The unit also comprises a range of syn- to post- tectonic granites which intruded Damaran sedimentary rocks during the Damaran Orogeny. Complex igneous intrusions with ages of about 135 Ma occur in a zone extending northeast from the coast north of Swakopmund. Some of them are extremely complex layered intrusions and contain rhyolite, grano phyre, granite, syenite, foyaite, gabbro, dunite, pyroxenite and carbonatite. They are not related to any orogeny and are interpreted as resulting from a hot mantle plume.
+
|12||Granite, gneiss and old volcanic rocks||Epupa and Kunene complexes; Orange River Group; Vioolsdrif Suite; Elim Formation; Khoabendus Group; Reheboth Sequence; Namaqualand Metamorphic Complex; Sinclair Sequence; Fransfontein Suite and Gamsberg Granite||Archaean to Jurassic||This unit includes a multitude of lithologies that almost covers the entire geological history of Namibia. Vaalian rocks comprise the gneisses of the Epupa Complex and the intrusives of the Kunene Complex. Early Mokolian rocks include gneisses and meta-volcanics of the old metamorphic complexes, metavolcanics of the Orange River Group, granites of the Vioolsdrif Suite, gneisses of the Elim Formation and meta-volcanics and gneisses of the Khoabendus Group. Middle to late Mokolian rocks of this unit are the meta-volcanics of the Rehoboth Sequence, the gneisses of the Namaqualand Metamorphic Complex, the meta-volcanics of the Sinclair Sequence, the granites of the Fransfontein Suite, as well as the younger granites, for example the Gamsberg Granite. The unit also comprises a range of syn- to post- tectonic granites which intruded Damaran sedimentary rocks during the Damaran Orogeny. Complex igneous intrusions with ages of about 135 Ma occur in a zone extending northeast from the coast north of Swakopmund. Some of them are extremely complex layered intrusions and contain rhyolite, grano phyre, granite, syenite, foyaite, gabbro, dunite, pyroxenite and carbonatite. They are not related to any orogeny and interpreted as a result of a hot mantle plume.
 
|}
 
|}
  
 
==Hydrogeology==
 
==Hydrogeology==
  
An Atlas country hydrogeology map has not been developed for Namibia, as a higher resolution hydrogeological map is already available. The hydrogeology of Namibia is described in detail in the report [https://www.bgr.bund.de/EN/Themen/Wasser/Projekte/abgeschlossen/TZ/Namibia/groundwater_namibia.pdf?__blob=publicationFile&v=3 Groundwater in Namibia] (Christelis & Struckmeier 2001/2011), which accompanies the Hydrogeological Map of Namibia. The following section provides a summary. Readers wishing more detailed information should consult the detailed report ([https://www.bgr.bund.de/EN/Themen/Wasser/Projekte/abgeschlossen/TZ/Namibia/groundwater_namibia.pdf?__blob=publicationFile&v=3 Christelis & Struckmeier 2001/2011)]) and/or the references given below, many of which are available through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].  
+
The hydrogeology of Namibia is described in detail in the report [http://www.namhydro.com/downloads.html Groundwater in Namibia] (ed. Christelis & Struckmeier 2011), which accompanies the Hydrogeological Map of Namibia. The following section provides a summary. Readers wishing more detailed information should consult the detailed report (ed. Christelis & Struckmeier 2011) and/or the references given below, many of which are available through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].  
  
 
The aquifers of Namibia have been classed according to whether they are consolidated (hard rock) or unconsolidated; according to the type of porosity and permeability they show (porous/intergranular or fractured, fissured or karstified); and according to how much groundwater resource potential they have. They have also been qualified according to the presence of saline or otherwise poor quality groundwater. The hydrogeological map, shown below, shows the distribution of these aquifer types across the country. General properties of each of the main aquifer types are given in the table below.  
 
The aquifers of Namibia have been classed according to whether they are consolidated (hard rock) or unconsolidated; according to the type of porosity and permeability they show (porous/intergranular or fractured, fissured or karstified); and according to how much groundwater resource potential they have. They have also been qualified according to the presence of saline or otherwise poor quality groundwater. The hydrogeological map, shown below, shows the distribution of these aquifer types across the country. General properties of each of the main aquifer types are given in the table below.  
  
Namibia is also covered by the SADC hydrogeological map and atlas (2010), available through the [https://ggis.un-igrac.org/ggis-viewer/viewer/sadcgip/public/default SADC Groundwater Information Portal].
+
[[File:simple-hgcl-map.png]] | 500x195px]]
 
 
[[File:Namibia_Hydrogeology2.png | center | frame | 200px| Hydrogeological map of Namibia. Image courtesy of Christelis & Struckmeier 2001 (2011)]]
 
  
  
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||Recharged by river leakage when ephemeral Kuiseb River flows
 
||Recharged by river leakage when ephemeral Kuiseb River flows
 
|-
 
|-
|Cuvelai-Etosha Basin (Unit 1 and 2), including Ohangwena Aquifer System (Unit 2)
+
|Ohangwena Aquifer System (Unit 1)
 +
||
 +
||
 +
||
 +
|-
 +
|Cuvelei-Ethosa Basin (Unit 1 and ?)
 
||This is a three layered system dominated by unconsolidated sand with some sandstones, with an average aquifer thickness of 220 m. It has a high primary porosity with no secondary porosity, and high horizontal connectivity. The average transmissivity value is 220 m²/day. The average piezometric level is 30 m below ground level, and the aquifer is mostly confined, but in some parts is unconfined. Typical borehole depth is 100 to 250 m.  
 
||This is a three layered system dominated by unconsolidated sand with some sandstones, with an average aquifer thickness of 220 m. It has a high primary porosity with no secondary porosity, and high horizontal connectivity. The average transmissivity value is 220 m²/day. The average piezometric level is 30 m below ground level, and the aquifer is mostly confined, but in some parts is unconfined. Typical borehole depth is 100 to 250 m.  
 
||About 35% of the deep aquifer has groundwater that is unsuitable for drinking water.
 
||About 35% of the deep aquifer has groundwater that is unsuitable for drinking water.
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|-
 
|-
 
|}
 
|}
 +
 +
Key sources of more information on some these aquifers are:
 +
 +
''Cuvelai-Ethosa Basin:''
 +
 +
Falk L and Christelis G. 2012. Groundwater for the North of Namibia (Cuvelai-Etosha Basin)- Exploration of Ohangwena two Aquifer and Preliminary Isotope study. Department of Water Affair and Forestry/BGR
  
 
====Fractured, Fissured or Karstified Aquifers====
 
====Fractured, Fissured or Karstified Aquifers====
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||The aquifer is recharged mainly by direct infiltration of rainfall over areas of quartzite outcrop. A new system of artificially recharging the Windhoek aquifer has recently been tested. Treated water from Von Bach Dam is pumped into the Windhoek production boreholes and stored underground to reduce water losses from evaporation. Many years of abstraction have lowered the water table, creating enough open pore space to allow infiltration of up to 50 Mm³ of water when the dams are sufficiently full.
 
||The aquifer is recharged mainly by direct infiltration of rainfall over areas of quartzite outcrop. A new system of artificially recharging the Windhoek aquifer has recently been tested. Treated water from Von Bach Dam is pumped into the Windhoek production boreholes and stored underground to reduce water losses from evaporation. Many years of abstraction have lowered the water table, creating enough open pore space to allow infiltration of up to 50 Mm³ of water when the dams are sufficiently full.
 
|-
 
|-
|Caprivi Aquifer (Nata Karoo Sub-basin) (Units 5 and 2)
+
|Caprivi Aquifer (Nata Karoo Sub-basin) (Units 5 and 6?)
 
||The Caprivi aquifer underlies the unconsolidated Kalahari Sequence (see above)and has an average thickness of 82 m. The formation has high primary porosity, and high vertical and horizontal connectivity. The average transmissivity is 193 m²/day.  
 
||The Caprivi aquifer underlies the unconsolidated Kalahari Sequence (see above)and has an average thickness of 82 m. The formation has high primary porosity, and high vertical and horizontal connectivity. The average transmissivity is 193 m²/day.  
  
Groundwater levels are generally shallow. The aquifer is confined. Variable borehole yields from less than 1 to more than 20 m³/hour occur. Borehole depths vary from 50 to 150 m.
+
Groundwater levels are generally shallow. The aquifer is confined. Variable borehole yields from zero to more than 20 m³/hour are seen. Borehole depths vary from 50 to 150 m.
 
||About 60% of the shallow aquifer is unsuitable for drinking water.
 
||About 60% of the shallow aquifer is unsuitable for drinking water.
 
||Total mean annual recharge is 15 Mm³
 
||Total mean annual recharge is 15 Mm³
Line 323: Line 222:
 
!colspan="4"|Fractured, Fissured or Karstified Aquifers with Moderate Potential
 
!colspan="4"|Fractured, Fissured or Karstified Aquifers with Moderate Potential
 
|-
 
|-
|Eiseb Aquifer (Northern Kalahari / Karoo Basin)  (Unit 2)
+
|Eiseb Aquifer (Northern Kalahari / Karoo Basin)  (Units 5 and 6?)
 
||This aquifer is a 2 layer system with both shallow Kalahari unconsolidated sedimentary sands (see above), and deeper Karoo consolidated sedimentary rocks, which may hold some potential for increased amounts of water, although this is still uncertain. The presence of a palaeo channel that contains abundant groundwater within a largely surrounding water scarce area is an example of the groundwater potential. The average aquifer thickness is around 130 m. The aquifer is mainly confined, although parts are unconfined. The average transmissivity values are 150 m²/day. Typical borehole depths are between 120 and 180 m.
 
||This aquifer is a 2 layer system with both shallow Kalahari unconsolidated sedimentary sands (see above), and deeper Karoo consolidated sedimentary rocks, which may hold some potential for increased amounts of water, although this is still uncertain. The presence of a palaeo channel that contains abundant groundwater within a largely surrounding water scarce area is an example of the groundwater potential. The average aquifer thickness is around 130 m. The aquifer is mainly confined, although parts are unconfined. The average transmissivity values are 150 m²/day. Typical borehole depths are between 120 and 180 m.
 
||About 20% of the aquifer contains groundwater that is unsuitable for drinking water.
 
||About 20% of the aquifer contains groundwater that is unsuitable for drinking water.
 
||Mean annual recharge is 10 Mm³/annum
 
||Mean annual recharge is 10 Mm³/annum
 
|-
 
|-
|SE Kalahari Karoo Basin (Units 5 and 9)
+
|SE Kalahari Karoo Basin (Units 5 and 6?)
 
||The aquifer is dominated by sandstones and shales, overlain by unconsolidated Kalahari sediments. Dolerite sills and dykes occur, more frequently towards the central parts of the basin, and sometimes enhance the level of fracturing within the sedimentary rock. The sandstones are characterized by a high primary porosity, and by secondary porosity fractures. There is a high horizontal connectivity while the vertical connectivity is generally low. The average transmissivity values are relatively low although the variation is relatively large within the system. The average transmissivity is 20 m²/day.
 
||The aquifer is dominated by sandstones and shales, overlain by unconsolidated Kalahari sediments. Dolerite sills and dykes occur, more frequently towards the central parts of the basin, and sometimes enhance the level of fracturing within the sedimentary rock. The sandstones are characterized by a high primary porosity, and by secondary porosity fractures. There is a high horizontal connectivity while the vertical connectivity is generally low. The average transmissivity values are relatively low although the variation is relatively large within the system. The average transmissivity is 20 m²/day.
 
||
 
||
||Mean annual recharge is around 135 Mm³.
+
||
 
|-
 
|-
 +
|}
 +
 +
Key sources of more information on these aquifers are:
 +
 +
''Windhoek Aquifer:''
 +
 +
Environmental Engineering Services. 2009. Artificial Recharge of the Windhoek Aquifer as best option for supply augmentation to the Central Area of Namibia. Draft Report, Department of Water Affairs and Forestry (unpublished).
 +
 +
''Caprivi Aquifer (Nata Karoo Sub-basin):''
 +
 +
Margane A, Roland B, Schildknecht F and Wierenga A. 2005. Groundwater investigation in the Eastern Caprivi Region - Main Hydrogeological report. Technical report, Department of Water Affairs and Foresty/BGR
 +
 +
 +
''The Eiseb Aquifer (Northern Kalahari / Karoo Basin):''
 +
 +
Margane A. 2004. Investigation of Groundwater Resources and Airborne-Geophysical Investigation of Selected Mineral Targets in Namibia-Groundwater investigation in the Eiseb Graben, Evaluation of Pumping Test. Department of Water Affairs (DWA), Namibia/Federal Institute for Geosciences and Natural Resources (BGR)
 +
 +
 +
''SE Kalahari Karoo Basin:''
 +
 +
Pacific Consultants International. 2002. The Study on the groundwater potential evaluation and management plan in the Southeast Kalahari (Stampriet) artesian basin in the Republic of Namibia. Japan International Cooperation Agency (JICA) and Department of Water Affairs and Forestly (DWAF)
 +
 +
Margane A, Roland B, Schildknecht F and Wierenga A. 2005. Groundwater investigation in the Eastern Caprivi Region - Main Hydrogeological report. Technical report, Department of Water Affairs and Foresty/BGR
 +
 +
====Rock Bodies With Little Groundwater Potential====
 +
{| class = "wikitable"
 +
|Named Aquifers||General Description||Water quantity issues||Water quality issues||Recharge
 +
|-
 +
|Aquitards / Rock Bodies with Generally Low but Locally Moderate Potential||G ||||||
 +
|-
 +
|Aquicludes / Rock Bodies with Very Low and Limited Potential|| || || ||
 
|}
 
|}
  
Line 361: Line 291:
 
==Groundwater-Surface Water Interaction==
 
==Groundwater-Surface Water Interaction==
  
Groundwater-surface water interaction is strong along the perennial rivers at the northern and southern borders (Kunene and Okavango in the north, Orange in the south), but this is not widely accounted for by the basin management bodies.
+
Groundwater-surface water interaction is strong along the perennial rivers at the northern and southern borders (Kunene and Kavango in the north, Orange in the south), but this is not widely accounted for by the basin management bodies.
  
 
Recharge of alluvial aquifers, especially in the coastal basins, depends on high run-off events in ephemeral rivers, which tend to occur at 4 to 8 year intervals.
 
Recharge of alluvial aquifers, especially in the coastal basins, depends on high run-off events in ephemeral rivers, which tend to occur at 4 to 8 year intervals.
Line 369: Line 299:
 
Many farm or earth dams exist in the country - estimates are up to 1000 - which are partly used to recharge groundwater to improve yields of water supply boreholes.
 
Many farm or earth dams exist in the country - estimates are up to 1000 - which are partly used to recharge groundwater to improve yields of water supply boreholes.
  
The potential for storing surface water in, for example, the Windhoek Aquifer, is not currently fully utilised. Managed Aquifer Recharge (MAR) could be key to dealing with increasing future demand. This will particularly be true in the case of an increase of extreme climatic events, as predicted  in numerous climatic models.
+
The potential for storing surface water in, for example, the Windhoek Aquifer, is not currently utilised. Managed Aquifer Recharge (MAR) could be key to dealing with increasing future demand. This will particularly be true in the case of an increase of extreme climatic events, as predicted  in numerous climatic models.
  
 
In the Caprivi aquifer (Nata Karoo Sub-basin), although recharge occurs predominantly through direct precipitation, some recharge from rivers also occurs along the major drainage channels within the northern parts of the aquifer.
 
In the Caprivi aquifer (Nata Karoo Sub-basin), although recharge occurs predominantly through direct precipitation, some recharge from rivers also occurs along the major drainage channels within the northern parts of the aquifer.
  
In the Cuvelai-Etosha Basin, some recharge from the Okavango River system in Angola is probably occurring.
+
In the Cuvelai-Ethosa Basin, some recharge from the Okavango River system in Angola is probably occurring.
  
 
In the Eiseb Aquifer (Northern Kalahari / Karoo Basin) the majority of recharge occurs through surface runoff.
 
In the Eiseb Aquifer (Northern Kalahari / Karoo Basin) the majority of recharge occurs through surface runoff.
  
In the southeast Kalahari Karoo Basin, although the main recharge mechanism is through direct precipitation over depressions situated on the northwestern edge of the basin, a certain amount of recharge also occurs through major rainfall event runoff in the ephemeral rivers that flow across the aquifer system.
+
In the southeast Kalahari Karoo Basin, although the main recharge mechanism is through direct precipitation, a certain amount of recharge also occurs through major rainfall event runoff in the ephemeral rivers that flow across the aquifer system.
  
 
===Groundwater dependent ecosystems===
 
===Groundwater dependent ecosystems===
Line 383: Line 313:
 
Groundwater dependent ecosystems occur in west-flowing rivers and at river mouths. Riverine vegetation is dependent on shallow, fresh to brackish groundwater from alluvial aquifers, in an otherwise arid environment with saline groundwater. Animals such as the world renown ‘desert elephant’ also depend on that groundwater resource.
 
Groundwater dependent ecosystems occur in west-flowing rivers and at river mouths. Riverine vegetation is dependent on shallow, fresh to brackish groundwater from alluvial aquifers, in an otherwise arid environment with saline groundwater. Animals such as the world renown ‘desert elephant’ also depend on that groundwater resource.
  
In the Cuvelai-Etosha Basin, shallow groundwater and groundwater dependent ecosystems cover around 5% of the area.
+
In the Cuvelai-Ethosa Basin, shallow groundwater and groundwater dependent ecosystems cover around 5% of the area.
  
 
Groundwater in Coastal Basins often feeds estuaries along the coastline, forming prominent ecosystems, such as at Sandwich Harbour south of Walvis Bay, and the Orange River estuary on the border with South Africa.
 
Groundwater in Coastal Basins often feeds estuaries along the coastline, forming prominent ecosystems, such as at Sandwich Harbour south of Walvis Bay, and the Orange River estuary on the border with South Africa.
Line 451: Line 381:
 
• Borehole hand pump
 
• Borehole hand pump
  
• Improved spring discharge
+
• Improved spring
  
 
===Groundwater Management and Monitoring===
 
===Groundwater Management and Monitoring===
Line 457: Line 387:
 
The main institutions involved in groundwater management are:
 
The main institutions involved in groundwater management are:
  
- the Department of Water Affairs and Forestry, Directorate Resource Management. General observation/management
+
- the Department of Water affairs and Forestry, Directorate Resource Management. General observation/management
 
+
- the Department of Water affairs and Forestry, Directorate Rural Water Supply and Sanitation. Coordination for rural usage
- the Department of Water Affairs and Forestry, Directorate Rural Water Supply and Sanitation. Coordination for rural usage
 
 
 
 
- NamWater. For bulk supply
 
- NamWater. For bulk supply
  
Line 472: Line 400:
 
• The Namibia Water Corporation Act, Act No 12 of 1997
 
• The Namibia Water Corporation Act, Act No 12 of 1997
  
• The Namibia Water Resources Management Act No 24 of 2004 – which was never commenced, and was subsequently revised (see next item)
+
• The Namibia Water Resources Management Act No 24 of 2004 – which was never commenced
  
• The Revised Namibia Water Resources Management Act, which was gazetted in December 2013
+
• The Revised Namibia Water Resources Management Act, whcih was gazetted in December 2013
  
 
New institutions with a role in groundwater management are:
 
New institutions with a role in groundwater management are:
  
• The Water Regulator - currently performed through the Department of Water Affairs
+
• The Water Regulator
  
• The Water Advisory Council - not as yet established
+
• The Water Advisory Council
  
 
• The Basin Management Committees
 
• The Basin Management Committees
  
• The Water Tribunal - not as yet established
+
• The Water Tribunal
  
 
• Water Point Committees
 
• Water Point Committees
  
A particularly practical groundwater management activity is the delineation of groundwater control areas, which include the most highly productive aquifers, to promote the use of groundwater resources on a long-term sustainable basis.
+
A particular practical groundwater management activity is the delineation of groundwater control areas, which include the most highly productive aquifers, to promote the use of groundwater resources on a long-term sustainable basis.
  
 
====Groundwater Monitoring====
 
====Groundwater Monitoring====
Line 498: Line 426:
 
Monitoring data have in the past been stored in the Geohydrology Division filing system, but a National Groundwater Database (GROWAS) has been designed to be the main storage facility for groundwater monitoring data, and is under improvement.
 
Monitoring data have in the past been stored in the Geohydrology Division filing system, but a National Groundwater Database (GROWAS) has been designed to be the main storage facility for groundwater monitoring data, and is under improvement.
  
==Transboundary aquifers==
+
=== Transboundary aquifers===
  
 
A number of transboundary aquifers occur in Namibia, the main ones of which are:
 
A number of transboundary aquifers occur in Namibia, the main ones of which are:
Line 504: Line 432:
 
• The Caprivi Aquifer (Nata Karoo Sub-basin)
 
• The Caprivi Aquifer (Nata Karoo Sub-basin)
  
• The Cuvelai-Etosha Basin
+
• The Cuvelai-Ethosa Basin
  
 
• The Eiseb Aquifer (Northern Kalahari / Karoo Basin
 
• The Eiseb Aquifer (Northern Kalahari / Karoo Basin
Line 511: Line 439:
  
 
All were included in the Transboundary Waters Assessment Programme (TWAP) carried out by GEF/UNESCO. More information about TWAP can be found on the [[Transboundary aquifers | Transboundary aquifers resources page]].
 
All were included in the Transboundary Waters Assessment Programme (TWAP) carried out by GEF/UNESCO. More information about TWAP can be found on the [[Transboundary aquifers | Transboundary aquifers resources page]].
 
The Department of Water Affairs and Forestry (DWAF), with BGR, carried out a project on the [https://www.bgr.bund.de/EN/Themen/Wasser/Projekte/abgeschlossen/F+E/Kalahari/kalahari_projektbeschr_en.html hydrogeology and sedimentology of the Kalahari Sediments of the Cuvelai-Etosha Basin]. More information can be found on the [[Namibia Groundwater Projects]] page.
 
 
==Groundwater Projects==
 
 
Information on major groundwater projects in Namibia, including links to project results and outputs, can be found on the [[Namibia Groundwater Projects]] page.
 
 
The [http://www.namhydro.com/index.html '''Namibian Hydrogeological Association'''], a non-profit network of groundwater professionals, maintains a website with details of members and the main groundwater projects they have worked on.
 
 
==References==
 
 
Many of the references listed on this page, and others relating to the hydrogeology of Namibia, can be accessed through the [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=listResults&title_search=&author_search=&category_search=&country_search=ZM&placeboolean=AND&singlecountry=1 Africa Groundwater Literature Archive].
 
 
Key report:
 
Christelis G and Struckmeier W (Editors). 2001 (2011). [http://www.bgr.bund.de/EN/Themen/Wasser/Projekte/abgeschlossen/TZ/Namibia/groundwater_namibia.pdf?__blob=publicationFile Groundwater in Namibia: an explanation to the Hydrogeological Map]. Ministry of Agriculture, Water and Rural Development, Namibia. (First edition December 2001; unrevised second edition January 2011).
 
 
 
Many of the project reports listed below can be accessed via the project details in the [[Namibia Groundwater Projects]] page.
 
 
''Cuvelai-Etosha Basin:''
 
 
Falk L and Christelis G. 2012. Groundwater for the North of Namibia (Cuvelai-Etosha Basin)- Exploration of Ohangwena two Aquifer and Preliminary Isotope study. Department of Water Affairs and Forestry/BGR
 
 
 
''Windhoek Aquifer:''
 
 
Environmental Engineering Services. 2009. Artificial Recharge of the Windhoek Aquifer as best option for supply augmentation to the Central Area of Namibia. Draft Report, Department of Water Affairs and Forestry (unpublished).
 
 
 
''Caprivi Aquifer (Nata Karoo Sub-basin):''
 
 
Margane A, Roland B, Schildknecht F and Wierenga A. 2005. Groundwater investigation in the Eastern Caprivi Region - Main Hydrogeological report. Technical report, Department of Water Affairs and Foresty/BGR
 
 
 
''The Eiseb Aquifer (Northern Kalahari / Karoo Basin):''
 
 
Margane A. 2004. Investigation of Groundwater Resources and Airborne-Geophysical Investigation of Selected Mineral Targets in Namibia-Groundwater investigation in the Eiseb Graben, Evaluation of Pumping Test. Department of Water Affairs (DWA), Namibia/Federal Institute for Geosciences and Natural Resources (BGR)
 
 
 
''SE Kalahari Karoo Basin:''
 
 
Pacific Consultants International. 2002. The Study on the groundwater potential evaluation and management plan in the Southeast Kalahari (Stampriet) artesian basin in the Republic of Namibia. Japan International Cooperation Agency (JICA) and Department of Water Affairs and Forestly (DWAF)
 
 
 
''General online resources''
 
 
[https://ggis.un-igrac.org/ggis-viewer/viewer/sadcgip/public/default SADC Groundwater Information Portal]
 
 
[http://www.sadc.int/themes/natural-resources/water/ General information on surface water and groundwater resources in SADC]
 
  
  
Return to
 
[[Overview of Africa Groundwater Atlas | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]]
 
  
 
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