Hydrogeology of Republic of Congo
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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 This information is outdated.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.
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.
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Koppen Geiger Climate Zones -
Average Annual Precipitation -
Average Temperature
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.
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Soil
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Land cover
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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).
| 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).
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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