Hydrogeology of Republic of Congo

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Africa Groundwater Atlas >> Hydrogeology by country >> Hydrogeology of the Republic of the Congo


Most of the textual information on this page was taken from the chapter on the Congo in the report ‘Groundwater in Eastern, Central and Southern Africa’ (UN 1989). This information is outdated. If you have more recent information on the hydrogeology of the Republic of the Congo, please get in touch.


Compilers

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

Geographical Setting

The Republic of the Congo lies on the equator. Parts of the country are relatively low lying plain areas, including the Congo Basin, the Niari valley and the coastal plain. Hills and plateaus surround the Congo Basin, and occur in other areas including the northwest and the central part of the country (including the Bateké plateaus), rising to over 800 m. The Mayombe range of mountains and the Chaillu massif also rise to over 800 m.

Map of the Republic of the Congo (For more information on the datasets used in the map see the geography resources section)

General

Estimated Population in 2013* 4,447,632
Rural Population (% of total) (2013)* 35.5%
Total Surface Area* 341,500 sq km
Agricultural Land (% of total area) (2012)* 31.0%
Capital City Brazzaville
Region Central Africa
Border Countries Gabon, Cameroon, Central African Republic, Democratic Republic of the Congo
Annual Freshwater Withdrawal (2013)* 46 Million cubic metres
Annual Freshwater Withdrawal for Agriculture (2013)* 8.7%
Annual Freshwater Withdrawal for Domestic Use (2013)* 69.6%
Annual Freshwater Withdrawal for Industry (2013)* 21.7%
Rural Population with Access to Improved Water Source (2012)* 38.8%
Urban Population with Access to Improved Water Source (2012)* 95.7%

* Source: World Bank


Climate

In the north of the country the climate is equatorial and rain occurs throughout the year, with two slightly less rainy periods from December to February and in July. The centre of the country is a sub-equatorial zone, with two distinct wetter seasons in March/April and October/November. The southwest is a wet tropical zone, with a rainy season that lasts from about October to May, and a dry season from June to September. Total rainfall everywhere is relatively high, at least 1000 mm/year and up to 3000 mm/year in the wettest zones.

Effective precipitation is also high, estimated for the years 1955 to 1970 at between 750 and 1250 mm/year in the coastal basin; 200 to 750 mm/year in the Niari valley and the Congo Basin; and 1000 to 1250 mm/year over the central plateaus.


Average monthly precipitation for the Republic of the Congo showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall Average monthly temperature for the Republic of the Congo 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)

For further detail on the climate datasets used see the climate resources section.

Surface water

There are many major rivers in the Republic of the Congo, in two main basins: the Congo River in the centre and north (which extends over several countries), and the Kouilou-Niari in the southwest. There are also small coastal basins, and the upper part of the Nyanga and Ogouué basins. Most are perennial, owing to the high rainfall and groundwater baseflow.


Surface Water Map of the Republic of the Congo (For more information on the datasets used in the map see the surface water resources section)

Soil

Soil Map of the Republic of the Congo (For map key and more information on the datasets used in the map see the soil resources section)

Land cover

Land Cover Map of the Republic of the Congo (For map key and more information on the datasets used in the map see the land cover resources section)


Geology

This section provides a summary of the geology of the Republic of the Congo. More information is available in the report Groundwater in Eastern, Central and Southern Africa: Congo (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).

Republic of Congo Geology.png
Geological Environments
Key Formations Period Lithology
Quaternary unconsolidated
River alluvium and coastal deposits Quaternary
Cenozoic
Cenozoic Found in the coastal plain and the central Bateké plateaus.
Mesozoic
Seen along the banks of the Congo River and its tributaries in Pool and in northern Likouala.
Precambrian
Precambrian Granitic basement rocks are seen in the Chaillu massif and in western Sangha. Metamorphic, deformed formations seen in the Mayombe mountains and also in the Niari valley, where there are also sub-horizontal sedimentary formations.


Hydrogeology

This section provides a summary of the hydrogeology of the main aquifers in the Republic of the Congo. More information is available in the report Groundwater in Eastern, Central and Southern Africa: Congo (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 Aquifer properties resource page for more details).

Republic of Congo Hydrogeology.png Hydrogeology Key.png


Unconsolidated

Named Aquifers Period General Description Water quality

Sedimentary - Intergranular Flow

Named Aquifers Period General Description Water quality

Sedimentary - Intergranular & Fracture Flow

Named Aquifers Period General Description Water quality

Sedimentary - Fracture Flow

Named Aquifers Period General Description Water quality

Basement

Named Aquifers Period General Description Water quality


Groundwater Status

Groundwater quantity

Groundwater quality

Groundwater use and management

Groundwater use

Groundwater management

In the 1980s, several government agencies were involved in water supply, including the Ministry of Planning (responsible for coordinating drinking water supply); the Department of Agricultural Engineering and Farm Machinery (DGRMA) (responsible for hydro-agricultural development, and also involved in village water supply drilling projects); the National Water and Energy Corporation (SNDE) (responsible for urban water supply); and the Ministry of Energy and Water Supply (established in 1984 and responsible for coordinating the study, exploitation and management of the country's water resources).

Until the late 1980s at least, there had been only a few groundwater studies, including the development of a groundwater supply for the town of Pointe-Noire in the 1950s; a number of local drinking and industrial water supply projects; some studies related to dam construction; and a [water resources planning map of Gabon and Congo published by BRGM and the Comite Interafricain d'Etudes Hydrauliques (CIEH)

Groundwater monitoring

Transboundary aquifers

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 the Republic of the Congo. They can also be accessed through the Africa Groundwater Literature Archive

CIEH/BRGM. 1982. Notice explicative de la carte de planification des ressources en eau du Gabon et du Congo. Serie hydrogeologie de Comite Interafricain d'Etudes Hydrauliques (CIEH), 116 pp, Ouagadougou, Burkina Faso.

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

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Africa Groundwater Atlas >> Hydrogeology by country >> Hydrogeology of the Republic of the Congo