Editing Hydrogeology of Burkina Faso

[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Hydrogeology by country | Hydrogeology by country]] >> Hydrogeology of Burkina Faso

==Authors==

'''Youssouf Koussoubé''', Université de Ouagadougou, Burkina Faso

'''Kirsty Upton''', '''Brighid Ó Dochartaigh''', British Geological Survey, UK

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

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

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==Geographical setting==

[[File:Burkina Faso_Political.png | right | frame | Burkina Faso. Map developed from USGS GTOPOPO30; GADM global administrative areas; and UN Revision of World Urbanization Prospects. For more information on the datasets used in the map see the [[Geography | geography resource page]]]] 

===General===

Much of Burkina Faso is a largely flat plain with an average altitude of 400 m above sea level, which is cut into by valleys and flood plains. 

{| class = "wikitable"
|-
|Estimated population in 2013* || 16 934 839
|-
|Rural population (% of total) (2013)* || 71.8%
|-
|Total surface area* || 273 600 sq km
|-
|Agricultural land (% of total area) (2012)* || 44.1%
|-
|Capital city || Ouagadougou
|-
|Region || Western Africa
|-
|Border countries || Benin, Cote d'Ivoire, Ghana, Mali, Niger, Togo  
|-
|Annual freshwater withdrawal (2013)* || 818 million cubic metres
|-
|Annual freshwater withdrawal for agriculture (2013)* || 51.4%
|-
|Annual freshwater withdrawal for domestic use (2013)* || 45.9%
|-
|Annual freshwater withdrawal for industry (2013)* || 2.7%
|-
|Rural population with access to improved water source (2012)* || 75.8%
|-
|Urban population with access to improved water source (2012)* || 97.5%
|}

<nowiki>*</nowiki> Source: World Bank


===Climate===

Burkina Faso can be divided into three climate zones, with rainfall decreasing from south to north. There is a distinct dry season during winter months, and wet season during summer months. 

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]].
<gallery widths="375px" heights=365px mode=nolines>
File:Burkina Faso_ClimateZones.png |Koppen Geiger Climate Zones 
File:Burkina Faso_ClimatePrecip.png |Average Annual Precipitation
File:Burkina Faso_ClimateTemp.png |Average Temperature
</gallery>



[[File: Burkina Faso_pre_Monthly.png| 255x124px| Average monthly precipitation for Burkina Faso showing minimum and maximum (light blue), 25th and 75th percentile (blue), and median (dark blue) rainfall]] [[File: Burkina Faso_tmp_Monthly.png| 255x124px| Average monthly temperature for Burkina Faso showing minimum and maximum (orange), 25th and 75th percentile (red), and median (black) temperature]] [[File: Burkina Faso_pre_Qts.png | 255x124px | Quarterly precipitation over the period 1950-2012]] [[File: Burkina Faso_pre_Mts.png|255x124px | Monthly precipitation (blue) over the period 2000-2012 compared with the long term monthly average (red)]] 
 

===Surface water===

The centre, south and west of Burkina Faso are drained by tributaries of the Volta system, including the Nakambe, Mouhoun and Comoé rivers. The north and east are drained by rivers of the Niger basin. Many of the smaller rivers are ephemeral, drying during the dry season. There are a number of natural lakes. Many valleys are dammed to store wet season rainfall: in 2001 there were approximately 2000 reservoirs with a total storage volume estimated at 2.66 billion cubic metres (Obuobie and Barry, 2012)


{|
|-
|


| [[File: Burkina Faso_Hydrology.png | frame |

Major surface water features of Algeria. 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 | surface water resource page]]]]
|}

===Soil===
{|
|-
| [[File: Burkina Faso_soil.png | frame | Soil Map of Burkina Faso, from the European Commission Joint Research Centre: European Soil Portal. For more information on the map see the [[Soil | soil resource page]]]]  

|
|}

===Land cover===
{|
|-
|

| [[File: BurkinaFaso_LandCover.png | frame | Land Cover Map of Burkina Faso, from the European Space Agency GlobCover 2.3, 2009. For  For more information on the map see the [[Land cover | land cover resource page]]]]
|}



==Geology==

This section provides a summary of the geology of Burkina Faso. More detail can be found in the references listed at the bottom of this page. Many of these references can be accessed through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].

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

A higher resolution map at 1:1 000 000 scale is published by the Ministere des Mines, des Carrieres et de l'Energie (Castaing et al., 2003a, 2003b).

[[File:BurkinaFaso_Geology3.png | centre | thumb| 500 px| Geology of Burkina Faso 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 | geology resource page]]]]

{| class = "wikitable"
|+ Geological environments
|Key formations||Period||Lithology||Structure
|-
!colspan="4"|Unconsolidated
|-
|Alluvium
||Quaternary
||Detrital deposits: dominantly alluvium in river valleys; some lake deposits.
||
|-
|Laterite
||Quaternary
||Iron-rich, hardened tropical soil
||
|-

!colspan="4"|Continental Terminal
|-
|
||Cenozoic 
||The Continental Terminal sequence unconformably overlies Proterozoic to Palaeozoic sedimentary dolomites and other formations in the Gondo plain in the north of the country. It consists largely of fluviatile and lacustrine deposits. In the north-west, it comprises a layer of alternating clays and sands 40 m thick; and in the easy, a conglomerate-sandstone succession (Castaing et al., 2003b).
||
|-

!colspan="4"| Proterozoic to Palaeozoic (meta)sedimentary
|-
|Bandiagara and Koutiala sandstones, Toun Schists, Bobo Sandstone, Gobinangou Sandstone
||Proterozoic (Late Precambrian) to Palaeozoic
||These are consolidated, indurated sedimentary rocks, sometimes metamorphosed, which unconformably overlie basement rocks. They occur along the north-west and north, and in the extreme south-east of the country. They include sandstone-quartzites and conglomerates at the base, which are overlain by largely sandstone formations, interbedded with schists and rare dolomitic limestones in the west of the country. At the top of the sequence are mixed formations including argillaceous schists, quartzitic sandstones, interbedded limestones and dolomites, breccias, and marbled conglomerates. In the south-east are sandstone facies (e.g. the Gobinangau Sandstone) with pelitic schists and calcareous and phosphated strata. 
||
|-
!colspan="4"| Crystalline basement
|-
|Birimian volcano-sedimentary and plutonic rocks; Eburnean granitoid rocks.
||Precambrian
||Basement complext of Archaean and Birimian age, consisting of belts of Birimian volcano-sedimentary and plutonic rocks intruded by large batholiths of Eburnean granitoid rocks. It includes basalt, andesite, rhyolite, rhyodacite, dacite, felsic tuffs, gabbro, diorite, granites, gneisses, shales, schists, quartzites and greenstones (Castaing et al., 2003b). 
||Two major north-north-east-trending sinistral shear zones divide the Basement rocks into three domains: eastern, central and western, with variably north-east or north to north-north-east-trending  structural features (Castaing et al., 2003b). 
|}

==Hydrogeology==

This section provides a summary of the hydrogeology of the main aquifers in Burkina Faso.  More information is available in the references listed at the bottom of this page. Many of these references can be accessed through the [http://www.bgs.ac.uk/africagroundwateratlas/index.cfm Africa Groundwater Literature Archive].

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

 [[File:BurkinaFaso_Hydrogeology3.png| center | thumb| 500px|| Hydrogeology of Burkina Faso at 1:5 million scale. For more information on how the map was developed see the [[Hydrogeology Map | Hydrogeology map]] resource page]]
Geology is the main control on aquifer productivity and groundwater potential. 

====Unconsolidated====
{| class = "wikitable"
|Named aquifers||General description||Water quantity issues||Water quality issues||Recharge
|-
|Alluvium  
||Alluvial deposits in river valleys and floodplains can have high permeability and storage capacity, where they are dominated by coarse-grained sand and gravel. Alluvium can be up to 60 m thick. Where they are underlain by permeable bedrock - e.g. sandstones or weathered basement - groundwater in the alluvial deposits is often in hydraulic continuity with groundwater in the underlying bedrock aquifer. It may also be in hydraulic continuity with river water in nearby rivers. The water table in alluvium is often shallow, less than 10 m below the ground surface (Obuobie and Barry, 2012). 


||Alluvial deposits are not continuous and therefore form local aquifers. They can be exploited by shallow wells and by deeper boreholes. 
|| 
||Recharge is by direct rainfall infiltration and leakage from rivers, and is strongly seasonal. 
|}

==== Sedimentary - intergranular flow====
{| class = "wikitable"
|Named aquifers||General description||Water quantity issues||Water quality issues||Recharge
|-
|Continental Terminal
||This aquifer has variable lithology and irregular structure. The upper layers comprise mudstones and sandstones. Sandstones form aquifer layers, which are generally in hydaulic continuity with the underlying older dolomitic limestone. Where they are overlain by unconsolidated alluvial aquifers, groundwater in the sandstone can be in hydraulic continuity with groundwater in the alluvium. The aquifer is largely unconfined.

The Continental Terminal aquifer ranges in thickness from 10 m thick at its edges, up to 100 m thick in the centre of the aquifer in the plain of Gondo. 

The water table can range from 10 m to more than 90 m below the ground surface. Borehole depths typically range from 40 m to 120 m.

Relatively high yields of at least 10 m³/hour may be obtainable from deep boreholes into sandstone layers (Obuobie and Barry, 2012). Data from the Burkina national borehole database indicate that average yields may be over 30 m³/hour. 
||
||
||Recharge is by direct rainfall infiltration and is strongly seasonal.
|}

==== Sedimentary - fracture flow====
{| class = "wikitable"
|Named aquifers||General description||Water quantity issues||Water quality issues||Recharge
|-
|Proterozoic to Palaeozoic (meta)sedimentary rocks
||Sandstones, dolomites and limestones form generally low productivity aquifer layers, which range from 50 to 1000 m thick. Dolomitic limestones form the best aquifers (BGS, 2002). The permeability of the upper aquifer layers has sometimes been enhanced by weathering (Obuobie and Barry, 2012). In some places they can be overlain by up to 60 m of alluvium, and groundwater is often in hydraulic continuity with the unconfined upper bedrock aquifer layers, with the water table ranging from 10 m to 60 m below the ground surface. The upper aquifer layers are typically unconfined. 

Lower aquifer formations can be confined if overlain by dolerite intrusions or clayey layer. In confined aquifer layers, borehole water levels are typically less than 5 m below the ground surface, and in some cases are artesian.

In the Bobo Diaoulasso area, fractured and weathered schists and dolomites form a 10-30 m thick weathered aquifer, in which average borehole yields of 0.5 to 5 m³/hour and transmissivity values of between approximately 15 and 50 m²/day have been recorded (Obuobie and Barry, 2012). 

The Gres and Intracambrian aquifers in the Bobo Dioulasso area are thought to be particularly productive aquifers. They are thought to be around 100 m thick and to have a transmissivity of approximately 120 to 415 m²/day and a specific capacity of 1 m³/hour/m (Obuobie and Barry, 2012). 

Yield data from the Burkina national borehole database indicates average borehole yields of around 4.5 m³/hour. 

||The aquifer is used for water supply in rural and urban areas (70% of abstraction from the aquifer); and also for mineral water and other commercial/industrial use (25%) and other uses.
|| 
||Most recharge to the aquifer is thought to occur from seasonal rainfall infiltration by preferential flow through fractures (Obuobie and Barry, 2012). 
|}

====Crystalline basement====
{| class = "wikitable"
|Named aquifers||General description||Water quantity issues||Water quality issues||Recharge
|-
|Granites, gneisses, schists, quartzites and greenstones.
||Basement rocks form discontinous aquifers. Groundwater storage and flow occur only where the rock is fractured and/or weathered. 

The upper part of the aquifer can be weathered to a depth of 10 m to 80 m. This weathered zone may be in hydraulic continuity with overlying alluvial aquifers (see Unconsolidated, above). The water table in the weathered zone can lie between 5 m and 30 m below the ground surface. Boreholes are typically from 40 m to 80 m deep. Groundwater in the weathered zone aquifer is typically unconfined.

Fractured bedrock, sometimes underlying and associated with, weathered zones, also forms an aquifer in the basement rocks. Fractured aquifer zones can range from 10 m to 80 m thick, and the water table can range from 20 m to 60 m below the ground surface. Boreholes abstracting from this aquifer are between 40 and 150 m deep.

Average borehole yields are around 2 m³/hour (Obuobie and Barry, 2012; yield data from the Burkina national borehole database).

||Groundwater from crystalline basement aquifers is dominantly used for rural water supplies (70%), with other uses being for mineral water and other commercial/industrial use (25%) and a small amount of abstraction for agriculture (2%).
||Groundwater is thought to be generally of Ca-Mg-HCO<sub>3</sub> type (BGS 2002). Arsenic has been identified as a problem in some areas, particularly associated with zones of gold mineralisation in Birimian (Lower Proterozoic) volcano-sedimentary rocks (Smedley et al., 2007).
||Recharge occurs from rainfall infiltration and is typically low. Indirect recharge in local depressions can be important (Obuobie and Barry, 2012). 
|}

==Groundwater Status==

===Groundwater quantity===

Average recharge rates are estimated at 5 mm/year in the drier north and 50 mm/year in the south, but local estimates range up to 250 mm/year (Obuobie and Barry 2012). 


===Groundwater quality===

Generally, groundwater in Burkina Faso is of suitable quality for drinking water supplies, although there are local problems. Naturally occuring arsenic has been identified as a problem in some areas, particularly associated with zones of gold mineralisation in Birimian (Lower Proterozoic) volcano-sedimentary rocks (Smedley et al. 2007). Pollution from nitrate is thought to be common in shallow groundwater sources, derived from domestic waste as well as agricultural sources, often highest in areas of high housing density (BGS 2002). Groundwater in some areas of northwest Burkina Faso has high salinity (BGS 2002). 

==Groundwater use and management==

=== Groundwater use===

Groundwater in Burkina Faso is used mainly for domestic water supply, particularly in small towns and rural areas; the city of Bobo Diolasso also relies on groundwater. Groundwater supplies around 15% of water supply to the capital Ouagadougou, but is particularly important in the dry season. Some groundwater is used for small scale market garden irrigation, for example supporting dry season cultivation in the south. It is also used for for livestock watering. Industry is the smallest user of groundwater in the country (Obuobie and Barry 2012). 

Groundwater abstraction is mainly from boreholes and wells. Most boreholes are fitted with pumps: typically mechanised in urban areas, and hand pumps in rural areas. 


=== Groundwater management===

The Ministere de l'Environment et de L'Eau (MEE) is the government department with responsibility for sustainable use of groundwater and surface water resources in Burkina Faso. Different MEE departments are responsible for different aspects of domestic, agricultural and industrial use of water and for energy production.

The National Council for Water is responsible for ensuring implementation of laws governing surface and groundwater management (Obuobie and Barry 2012). The Water Management Policy Act (2001) provided for state ownership of all water resources (with limited exceptions) and established a permit regime for water abstraction for non-domestic uses (Obuobie and Barry 2012). 

The national organisation with responsibility for water supply is the Office National de l’Eau et de l’Assainissement (ONEA).

There is a national borehole database which currently stores information about more than 15,000 boreholes. The database includes detailed information about borehole location (coordinates and village/region); depth; whether the borehole was successful; the geology; and the borehole yield.

=== Transboundary aquifers===

There are no major transboundary aquifers in Burkina Faso. 

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


==References==

The following references provide more information on the geology and hydrogeology of Burkina Faso.
These, and others, can be accessed through the [http://www.bgs.ac.uk/africagroundwateratlas/searchResults.cfm?title_search=&author_search=&category_search=&country_search=BF&placeboolean=AND&singlecountry=1 Africa Groundwater Literature Archive].


'''Useful websites'''

Bureau des Mines et de la Geologie du Burkina. http://www.bumigeb.bf/index.htm


===Geology: key references===

Castaing C, Le Metour J et Billa M (Coordonnateurs). 2003a. Carte géologique et minière du Burkina Faso à 1/1 000 000. Projet SYSMIN 7 ACP BK 074: Cartographie géologique au Burkina Faso; Ministere des Mines, des Carriers et de l'Energie; Direction des Etudes et de la Planification; financé par l'Union Européenne.

Castaing C, Billa M, Milési J P, Thieblemont D, Le Metour J, Egal F, Donzeau M (Coordonnateurs). 2003b. Notice explicative de la carte géologique et minière du Burkina Faso à 1/1 000 000. Projet SYSMIN 7 ACP BK 074: Cartographie géologique au Burkina Faso; Ministere des Mines, des Carriers et de l'Energie; Direction des Etudes et de la Planification; financé par l'Union Européenne.

Hottin G et Ouédraogo OF. 1975. Notice explicative de la carte géologique à 1/1 000 000 de la
- IWACO ·1989· Etude du bilan du Burkina Faso. Rapport intermédiaire de la deuxième phase 1987-1990. Tome 2 : inventaire des ressources en eau

Sattran V et Wenmenga U. 2002. Géologie du Burkina Faso (Czech Edition), 10 dec 2002, République de Haute-Volta, Edition BRGM, 56p

===Hydrogeology: key references===

BGS. 2002. Groundwater Quality: Burkina Faso. British Geological Survey. http://www.wateraid.org/~/media/Publications/groundwater-quality-information-burkina-faso.pdf

Ministère de l'eau. 1993. Notice explicative de la carte hydrogéologique du Burkina Faso échelle 1:5OO.OOO, feuille Ouagadougou - DEP du Ministètre de l'eau, Assistance technique : IWACO B.V., Financement: Burkina FasolPays-Bas, 4Sp. + cartes

Ministère de l'eau. 1988. Rapport de fin de projet : travaux et résultats hydrogéologiques - projet d'hydraulique villageoise Yatenga II, CCE, FED, Convention n034981BF, 48 p+annexes

Ministère de l'eau. 1990. Etude des ressources en eau souterraine du Yatenga - CIEH, série hydrogéologie, 138p.

Ministère de l'environnement et de l'eau. 1998. Politique et stratégies en matière d'eau 126p.

Obuobie E and Barry B. 2012. Burkina Faso, in Groundwater Availability and Use in Sub-Saharan Africa; a review of fifteen countries. Pavelic P et al. (Eds). International Water Management Institute, Sri Lanka. 

Smedley PL, Knudsen J and Maiga D. 2007. Arsenic in groundwater from mineralised Proterozoic basement rocks of Burkina Faso. Applied Geochemistry 22, 1074-1092. 

UN. 1988. Burkina Faso, in Ground water in North and West Africa. Natural Resources/Water Series No. 18, ST/TCD/5. Department of Technical Co-operation for Development and Economic Commission for Africa. 

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