Hydrogeology of Angola

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Africa Groundwater Atlas >> Hydrogeology by country >> Hydrogeology of Angola


The textual information on this page was taken from the references listed at the bottom of this page. This information may be outdated. If you have more recent information on the hydrogeology of Angola, please get in touch.


Compilers

Dr Kirsty Upton and Brighid Ó Dochartaigh, British Geological Survey, UK

Please cite this page as: Upton and Ó Dochartaigh, 2016.

Bibliographic reference: Upton, K, and Ó Dochartaigh, B É. 2016. Africa Groundwater Atlas: Hydrogeology of Angola. British Geological Survey. Accessed [date you accessed the information]. http://earthwise.bgs.ac.uk/index.php/Hydrogeology_of_Angola

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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 Terms of use for more information.

Geographical setting

Angola. Map developed from USGS GTOPOPO30; GADM global administrative areas; and UN Revision of World Urbanization Prospects. For more information on the datasets used to develop the map see the geography resource page

General

Angola is in central-southern Africa. There is a lowland coastal strip between 35 and 180 km wide that ranges from 300 to 500 m in elevation. Away from this, most of the country is formed of high plateaus from about 1000 to 1800 m in elevation, with the highest point at 2620 m. Hills and mountains rise inland from the coast into a major escarpment. Extending eastwards and south-eastwards from the escarpment is a large area of high plateau (planalto).


Estimated population in 2013* 21 471 618
Rural population (% of total) (2013)* 57.5%
Total surface area* 1 246 700 sq km
Agricultural land (% of total area) (2012)* 47.5%
Capital city Luanda
Region Central Africa
Border countries Namibia, the Democratic Republic of the Congo, Zambia
Annual freshwater withdrawal (2013)* 708.8 million cubic metres
Annual freshwater withdrawal for agriculture (2013)* 20.8%
Annual freshwater withdrawal for domestic use (2013)* 45.3%
Annual freshwater withdrawal for industry (2013)* 33.9%
Rural population with access to improved water source (2012)* 34.3%
Urban population with access to improved water source (2012)* 67.6%

* Source: World Bank


Climate

Most of Angola has a dry season from May to October and a rainy season from February to April, with transitional rains from November to January. The south of the country, and along parts of the coastal strip, are semi-arid, with less than 400 mm/year of rain. The far north sees rainfall throughout much of the year, with more than 1400 mm/year of rain. The climate is greatly influenced by prevailing winds from the west and south-west.

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 on the datasets used to develop these maps and graphs see the climate resource page.


Average monthly precipitation for Angola showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall Average monthly temperature for Angola showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature Quarterly precipitation over the period 1950–2012 Monthly precipitation (blue) over the period 2000–2012 compared with the long- term monthly average (red)


Surface water

The centre and north of Angola have many perennial rivers. In the south there are only three perennial rivers: the Cunene, Kuando and Cubango (which flows to the Okavango) rivers.

The Zambezi River and several tributaries of the Congo River have their sources in Angola. Many rivers originate in the central uplands, but take quite different flow paths. Some flow more or less due westerly to the Atlantic, providing water for irrigation and the potential for hydroelectric power in the dry coastal strip. Two of the largest rivers, the Cuanza and the Cunene, take a more indirect route to the Atlantic, the Cuanza flowing north and the Cunene flowing south before turning west. navigable. The Kwango and other rivers flow north from the high plateau to join the Kasai River (one of the largest tributaries of the Congo). Some rivers flow south into the Zambezi River system and from there to the Indian Ocean; others to the Okavango River (called the Cubango River in Angola) and thence to the Okavango Swamp in Botswana.


Major surface water features of Angola. Map developed from World Wildlife Fund HydroSHEDS; Digital Chart of the World drainage; and FAO Inland Water Bodies. For more information on the datasets used to develop the map see the surface water resource page

Soil

Soil Map of Angola, from the European Commission Joint Research Centre: European Soil Portal. For more information on the map see the soil resource page

Land cover

In the far south and south-west of Angola, land cover is dominated by desert or sparse savannah or grassland vegetation. This gives way northwards to shrubland and then to a mix of shrubland then to deciduous forest, which covers much of the rest of the country.


Land Cover Map of Angola, from the European Space Agency GlobCover 2.3, 2009. For more information on the map see the land cover resource page


Geology

This section provides a summary of the geology of Angola. More information is available in the report‘Groundwater in Eastern, Central and Southern Africa’ (UN 1989) (see References section, below).

The geology map shows a simplified version of the geology at a national scale (see the Geology resources page for more details).

Geology of Angola at 1:5 million scale. Developed from USGS map (Persits et al., 2002). For more information on how the map was developed see the geology resources page
Geological environments
Key formations Period Lithology
Unconsolidated/Semi-consolidated
Alluvium Quaternary Unconsolidated alluvial sediments infilling valleys.
Tertiary–Quaternary Kalahari Group Loosely consolidated sandstones and unconsolidated sands and silts, covering much of the eastern part of the country. Up to 600 m thick.
Consolidated sedimentary
Cretaceous–Tertiary Up to 150 m thickness of Aptian-Maastrichtian age sedimentary rocks, often argillaceous sandstones with marine and evaporitic deposits. Overlain by up to 1200 m thickness of Paleocene to Pliocene age sedimentary rocks.
Karoo Supergroup Carboniferous–Jurassic Argillaceous limestones, sandstones and shales at the edge of Congo Basin. Up to 500 m thick. Intruded by dolerites.
Volcanic rocks
Mesozoic
Precambrian
Bembé System Late Precambrian–Lower Cambrian Metasedimentary rocks: schist-limestones overlain by metasandstones, metaconglomerates and quartzites
Oendolongo System Precambrian Metasedimentary rocks: quartzitic metasandstones
Crystalline basement Archaean Crystalline igneous and metamorphic rocks, largely granites, gneisses and gabbros, part of the African craton. Often quartz veins.


Hydrogeology

This section provides a summary of the hydrogeology of the main aquifers in Angola. More information is available in the report‘Groundwater in Eastern, Central and Southern Africa’ (UN, 1989) (see References section, below).

The hydrogeology map shows a simplified version of the type and productivity of the main aquifers at a national scale (see the Hydrogeology Map resource page for more details).

A hydrogeological map of Angola at 1:1 500 000 scale was published by Hidroprojecto Consultores de Hidraulica e Salubridade SA (1990) (see Reference section, below).

Angola is also included in the overview hydrogeological map developed by the Southern African Development Community (SADC) (2010) (see Reference section, below).

Hydrogeology of Angola at 1:5 million scale. For more information on how the map was developed see the hydrogeology map resource page


Unconsolidated

Named aquifers Period General description Water quality
Alluvium Quaternary Variable groundwater potential, depending on the lithology (whether dominated by permeable sands and gravels or low permeability fine-grained deposits), thickness and lateral extent.

Sedimentary - Intergranular flow

Named aquifers Period General description Water quality
Kalahari Group Tertiary–Quaternary The water table in the Kalahari Group is shallower in the north and becomes deeper towards the south, where the Kalahari Group is typically completely dry (Groundwater Consultants Bee Pee (Pty) Ltd, SRK Consulting (Pty) Ltd, 2002).

Sedimentary - Intergranular and fracture flow

Named aquifers Period General description Water quality
Cretaceous–Tertiary Argillaceous sandstones along the coast have proved to be productive aquifers. Groundwater can be relatively highly mineralised, sometimes associated with salt-bearing formations.
Karoo Supergroup Carboniferous–Jurassic These can form productive aquifers. Groundwater can be relatively highly mineralised


Basement

Named aquifers Period General description Water quality
Crystalline basement and metasedimentary rocks Precambrian (locally Lower Cambrian) Form local aquifers, generally with low productivity, where fractured and/or weathered. The best groundwater potential is in zones of quartz veins and basic rocks; contact zones between crystalline rocks of different texture and composition; zones of fractured granitogneiss; and contact zones between metavolcanic and quartz-schist rocks.

Generally low productivity aquifers with low borehole yields, but some boreholes have shown up to 30 m³/hour in fractured gabbros. One study showed that borehole yield was directly related to the direction of tectonic structures (fracture orientation). For example, where fractures are in a NE-SW direction, yields are less than 3 m³/hour; and where fractures are in a N-S direction, yields are more than 8.5 m³/hour (United Nations, 1989).


Groundwater status

Only limited research has been conducted concerning groundwater and no national resource estimates have been completed. However, based on the presently identified potential and the limited level of existing development, it is safe to assume that only a very small portion of national groundwater resources are being used (Groundwater Consultants Bee Pee (Pty) Ltd, SRK Consulting (Pty) Ltd, 2002).

Although not presently monitored or evaluated, there has been a reported decline in water quality in the coastal part of Namibe Province, most likely related to salt water intrusion. However, other urban and rural water supply schemes using groundwater in the coastal belt have not reported saltwater intrusion (Groundwater Consultants Bee Pee (Pty) Ltd, SRK Consulting (Pty) Ltd, 2002).

Groundwater use and management

Groundwater use

Most urban centres are supplied from surface water, but the provincial capitals of Malange, Bengucia, Lubango and Namibe, as well as the urban centres of Tobwa and Lobito rely on groundwater to a greater or lesser extent. In general, groundwater use is concentrated in southern and coastal areas where conditions are more arid and surface water is less available. Additionally, groundwater is being increasingly developed for local systems to augment urban supply in the rapidly growing peri-urban areas, particularly Luanda (Groundwater Consultants Bee Pee (Pty) Ltd, SRK Consulting (Pty) Ltd, 2002).

Rural areas largely rely on groundwater, from boreholes, hand-dug wells and springs. In areas where existing water supply systems are no longer working or have not been developed, surface water is more widely used (Groundwater Consultants Bee Pee (Pty) Ltd, SRK Consulting (Pty) Ltd, 2002).

Another major use of groundwater is for livestock in the southern provinces. Water supply for livestock watering is co-ordinated by the Ministry of Agriculture, and groundwater is supplied through boreholes and wells equipped with either manual or powered submersible pumps. In a 1973 survey there were 943 boreholes and 319 wells supporting such systems. The present number is not available, but based on recent figures available from Cunene Province, where 125 out of 607 systems are functioning, the current number of operable systems is likely to be less than in 1973. However, individual farmers and ranchers also commonly construct boreholes and wells in these southern areas (Groundwater Consultants Bee Pee (Pty) Ltd, SRK Consulting (Pty) Ltd, 2002).

Groundwater management and monitoring

The National Directorate for Water (DNA) are responsible for aspects of water supply and water resources.

In 2002 there was no formal institution responsible for data collection related to groundwater. However, since 1996, DNA have carried out annual field surveys of the operational status of water supply systems, including boreholes and hand-dug wells, to assess the level of water supply coverage. During these field campaigns, data collected includes the location of boreholes and hand-dug wells; the number of users of each borehole or well; the borehole/well depth; the rest water level; the type and mark of pump; the name of a responsible person; and the maintenance record over the previous year. This field information is kept in paper form in the DNA archive for future use, and used to compile annual reports summarising the total number of water point sources by province and a summary of their operational status. In 2002 there were records of over 3600 groundwater points (Groundwater Consultants Bee Pee (Pty) Ltd, SRK Consulting (Pty) Ltd, 2002).

Another institution collecting data related to groundwater is the company Hidromina, which maintains a digital database with basic information generated by boreholes they have drilled. In 2002, this database held records of over 2500 boreholes (Groundwater Consultants Bee Pee (Pty) Ltd, SRK Consulting (Pty) Ltd, 2002).

Transboundary aquifers

Angola shares a number of aquifers with other countries. These include (Altchenko and Vilholth, 2013):


- the Northern Kalahari/Karoo Basin, shared with Botswana, Namibia and Zambia

- Cuvelai–Etosha Basin, shared with Namibia

- the Coastal Sedimentary Basin (Cunene River) aquifer, shared with Namibia

- the Lower Congo Precambrian Dolomite aquifer and the Congo River Coastal Sedimentary aquifer, both shared with the Democratic Republic of the Congo.


For further information about transboundary aquifers, please see the Transboundary aquifers resources page


References

The following references provide more information on the geology and hydrogeology of Angola.

These, and others, can be accessed through the Africa Groundwater Literature Archive

Altchenko, Y, and Vilholth, K G. 2013. Transboundary aquifer mapping and management in Africa: a harmonised approach. Hydrogeology Journal, Vol.21, Issue 7, 1497–1517.

Groundwater Consultants Bee Pee (Pty) Ltd, SRK Consulting (Pty) Ltd. 2002. Compilation of the hydrogeological map atlas for the SADC region: Situation Analysis Report Annex A - Angola. SADC Water Sector Coordinating Unit.

Hidroprojecto Consultores de Hidraulica e Salubridade SA. 1990. Mapa Hidrogeologico de Angola. Scale 1:1,500,000. Lisboa & MacDonald & Partners Ltd Cambridge.

SADC. 2010. Technical Assistance to the SADC - 'SADC Hydrogeological Mapping Project' (9 ACP RPR 39-89); Final Report. Southern African Development Community European Development Fund, HGM-1, March 2010; a technical report to the Southern African Development Community (SADC) and Cooperating Partners: European Union and GTZ.

United Nations. 1989. Groundwater in Eastern, Central and Southern Africa: Angola. United Nations Department of Technical Cooperation for Development, Natural Resources/Water Series, No.19, ST/TCD/6.

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