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Benin’s economy is heavily dependent on agriculture. Most of the population is employed in subsistence agriculture, and commercial agriculture for export is a key contributor to the economy, particularly cotton, which accounts for around 40% of GDP and 80% of official export receipts. Other agricultural products are also important economically, including wood. The service sector is the largest single contributor to GDP, driven by trade and transportation links with neighbouring countries, and tourism. Petrochemical exports were significant in the 1980s, when offshore reserves were extracted, but these operations declined in the 1990s, although Benin is exploring the possibility of revamping petrochemical production post 2020.  
 
Benin’s economy is heavily dependent on agriculture. Most of the population is employed in subsistence agriculture, and commercial agriculture for export is a key contributor to the economy, particularly cotton, which accounts for around 40% of GDP and 80% of official export receipts. Other agricultural products are also important economically, including wood. The service sector is the largest single contributor to GDP, driven by trade and transportation links with neighbouring countries, and tourism. Petrochemical exports were significant in the 1980s, when offshore reserves were extracted, but these operations declined in the 1990s, although Benin is exploring the possibility of revamping petrochemical production post 2020.  
  
Average annual rainfall in Benin is relatively high, but varies considerably by season as well as across the country. The south of Benin, in particular, has good surface water resources in perennial rivers, but groundwater is widely used across the country in rural and urban areas for domestic water supply. The capital Cotonou depends extensively on groundwater. Aquastat figures (see below) show relatively high rates of access to improved water sources, but Benin government figures, which use a different definition of access, show much lower rates: 57% in urban areas and 55% in rural areas in 2009.  
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Average annual rainfall in Benin is relatively high, but varies considerably by season as well as across the country. The south of Benin particularly has good surface water resources in perennial rivers. Groundwater is widely used in rural and urban areas for domestic water supply. Aquastat figures (see below) show relatively high rates of access to improved water sources, but Benin government figures, which use a different definition of access, show much lower rates: 57% in urban areas and 55% in rural areas in 2009.  
  
  
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==Geology==
 
==Geology==
 
 
This section provides a summary of the geology of Benin. More detail can be found in the references listed at the bottom of this page. Many of these references can be accessed through the [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=listResults&title_search=&author_search=&category_search=&country_search=BJ&placeboolean=AND&singlecountry=1 Africa Groundwater Literature Archive].
 
This section provides a summary of the geology of Benin. More detail can be found in the references listed at the bottom of this page. Many of these references can be accessed through the [https://www.bgs.ac.uk/africaGroundwaterAtlas/atlas.cfc?method=listResults&title_search=&author_search=&category_search=&country_search=BJ&placeboolean=AND&singlecountry=1 Africa Groundwater Literature Archive].
  
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===Groundwater status===
 
===Groundwater status===
 
 
Low yields from basement aquifers, which cover most of Benin, lead to difficulties with fresh water availability in medium to large cities.  
 
Low yields from basement aquifers, which cover most of Benin, lead to difficulties with fresh water availability in medium to large cities.  
  
 
Potable water supply is also an issue in parts of the coastal basin, where the saturated thickness of the shallow aquifers is not sufficient for large supplies. Where the shallow deposits are unable to sustain sufficient yields, boreholes are drilled deeper into the weathered basement below.
 
Potable water supply is also an issue in parts of the coastal basin, where the saturated thickness of the shallow aquifers is not sufficient for large supplies. Where the shallow deposits are unable to sustain sufficient yields, boreholes are drilled deeper into the weathered basement below.
  
Groundwater in shallow aquifers is often of poor quality due to contamination. Saline intrusion is a particular problem in the coastal aquifers. In the capital, Cotonou, groundwater is extensively abstracted, but studies have found that groundwater in the urban area contains levels of many contaminants above WHO guidelines, including lead, chromium, cadmium, zinc, coliforms and E.coli ([https://www.ajol.info/index.php/tjpr/article/view/14587 Erah and Akukieze 2002], [https://www.researchgate.net/publication/280839085_Groundwater_pollution_and_the_safe_water_supply_challenge_in_Cotonou_town_Benin_West_Africa Totin et al 2013).  
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Groundwater in shallow aquifers is often of poor quality due to contamination. Saline intrusion is a particular problem in the coastal aquifers.  
  
 
The Oueme River loses water to the permeable coastal sedimentary aquifer, and river flow depletion is therefore an issue in this river downstream of the contact between the Precambrian basement aquifer and the coastal sedimentary aquifer.  
 
The Oueme River loses water to the permeable coastal sedimentary aquifer, and river flow depletion is therefore an issue in this river downstream of the contact between the Precambrian basement aquifer and the coastal sedimentary aquifer.  
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For further general information about transboundary aquifers, please see the [[Transboundary aquifers | Transboundary aquifers resource page]]
 
For further general information about transboundary aquifers, please see the [[Transboundary aquifers | Transboundary aquifers resource page]]
  
==References==
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== References ==
 
 
 
The following references provide more information on the geology and hydrogeology of Benin.
 
The following references provide more information on the geology and hydrogeology of Benin.
  
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===Hydrogeology references===
 
===Hydrogeology references===
 
 
Key references are highlighted in '''bold'''.
 
Key references are highlighted in '''bold'''.
  
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'''Engalenc, M. 1978b'''. Méthode d’étude et de recherche de l’eau souterraine des roches cristallines de l’Afrique de l’Ouest. Rapport CIEH, 318 p. Ouagadougou. Haute-Volta.  
 
'''Engalenc, M. 1978b'''. Méthode d’étude et de recherche de l’eau souterraine des roches cristallines de l’Afrique de l’Ouest. Rapport CIEH, 318 p. Ouagadougou. Haute-Volta.  
 
Erah, P O and Akujieze, C N. 2002. [https://www.ajol.info/index.php/tjpr/article/view/14587 The Quality of Groundwater in Benin City: A baseline study on inorganic chemicals and microbial contaminants of health importance in boreholes and open wells]. Tropical Journal of Pharmaceutical Research, 1(2), 75-82.
 
  
 
'''Falola E, et Sotognon, F C. 2002'''. Impact de l’utilisation des intrants agricoles sur la qualité Chimique des nappes d’eaux souterraines dans les Départements du Borgou et de l’Alibori. Mémoire de Maîtrise, 59 p. Université d’Abomey-Calavi, Bénin.
 
'''Falola E, et Sotognon, F C. 2002'''. Impact de l’utilisation des intrants agricoles sur la qualité Chimique des nappes d’eaux souterraines dans les Départements du Borgou et de l’Alibori. Mémoire de Maîtrise, 59 p. Université d’Abomey-Calavi, Bénin.
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SOGREAH/SCET-Tunisie. 1998. Etude de la stratégie nationale de gestion des ressources en eau du Bénin: assistance à la définition de la stratégie nationale de gestion des ressources en eau du Bénin. 7 volumes. Rapport final, Ministère des Mines, de l’Energie et de l’Hydraulique, Cotonou, Bénin.
 
SOGREAH/SCET-Tunisie. 1998. Etude de la stratégie nationale de gestion des ressources en eau du Bénin: assistance à la définition de la stratégie nationale de gestion des ressources en eau du Bénin. 7 volumes. Rapport final, Ministère des Mines, de l’Energie et de l’Hydraulique, Cotonou, Bénin.
  
Totin, H. S., Amoussou, ERNEST, Odoulami, LÉOCADIE, Edorh, P A. Boukari M and Boko, M. 2013. [https://www.researchgate.net/publication/280839085_Groundwater_pollution_and_the_safe_water_supply_challenge_in_Cotonou_town_Benin_West_Africa Groundwater pollution and the safe water supply challenge in Cotonou town, Benin (West Africa). Proceedings of H, 4, 191-196].  
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Totin, V H S. 2003. Changements climatiques et vulnérabilité des ressources en eau sur le plateau d’Allada : approche prospective. Mémoire de Maîtrise, Université d’Abomey-Calavi, Bénin, Cotonou, Bénin, 101 p.
  
 
Totin,  V S H. 2010. Sensibilité des eaux souterraines du bassin sédimentaire côtier du Bénin à l’évolution du climat et aux modes d’exploitation : Stratégies de gestion durable. Thèse de Doctorat, Université d’Abomey-Calavi, Cotonou, Bénin, 283 p.
 
Totin,  V S H. 2010. Sensibilité des eaux souterraines du bassin sédimentaire côtier du Bénin à l’évolution du climat et aux modes d’exploitation : Stratégies de gestion durable. Thèse de Doctorat, Université d’Abomey-Calavi, Cotonou, Bénin, 283 p.
 
Totin, V H S. 2003. Changements climatiques et vulnérabilité des ressources en eau sur le plateau d’Allada : approche prospective. Mémoire de Maîtrise, Université d’Abomey-Calavi, Bénin, Cotonou, Bénin, 101 p.
 
  
 
Turkpak International-SCET-Tunisie. 1991. Inventaire des ressources en eaux souterraines au Bénin. Rapport final, Direction de l’Hydraulique, Cotonou, Bénin. 1. 284 p.  
 
Turkpak International-SCET-Tunisie. 1991. Inventaire des ressources en eaux souterraines au Bénin. Rapport final, Direction de l’Hydraulique, Cotonou, Bénin. 1. 284 p.  

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