Houemenou H., Tweed Sarah, Dobigny Gauthier, Mama D., Alassane A., Silmer R., Babic M., Ruy S., Chaigneau Alexis, Gauthier Philippe, Socohou A., Dossou H. J., Badou S., Leblanc M. (2020). Degradation of groundwater quality in expanding cities in West Africa. A case study of the unregulated shallow aquifer in Cotonou. Journal of Hydrology, 582, 124438 [16 p.]. ISSN 0022-1694.
Titre du document
Degradation of groundwater quality in expanding cities in West Africa. A case study of the unregulated shallow aquifer in Cotonou
Année de publication
2020
Auteurs
Houemenou H., Tweed Sarah, Dobigny Gauthier, Mama D., Alassane A., Silmer R., Babic M., Ruy S., Chaigneau Alexis, Gauthier Philippe, Socohou A., Dossou H. J., Badou S., Leblanc M.
Source
Journal of Hydrology, 2020,
582, 124438 [16 p.] ISSN 0022-1694
In Cotonou, as in many expanding West African cities, major population growth and infrastructural development has not kept up with informal settlement development onto floodable plains and marshes. The population of the slum, which makes up about 60% of the city's inhabitants, is highly disadvantaged and vulnerable to rising sea levels, flooding, sanitation and waste management issues. However, the risks associated with the use of contaminated shallow groundwater for domestic purposes are less recognised. Our study demonstrates that, in many instances, the cheaper option of the use of shallow groundwater from the coastal Quaternary aquifer for domestic purposes represents a significant risk for the poorer residents of Cotonou through the voluntary (drinking) or non-volontary (dish washing, cooking) consumption of this unmonitored and untreated water resource. In the 3 neighbourhoods surveyed, environmental tracers (major ions, Cl/Br molar ratios and stables isotopes) showed that this shallow aquifer is degraded by seawater intrusion as well as septic and sewerage contamination. In particular, the higher NOx concentrations correspond to ranges associated with sewerage and septic tank effluent pollution and the major ion concentrations and delta H-2-delta O-18 signatures showed that high salinity values are where groundwater mixes with saline Lake Nokoue water. The population using this resource from local wells should be made aware of seasonal changes in groundwater contamination and potential health risks associated with sewerage and septic tank contamination.
Plan de classement
Pollution [038]
;
Hydrologie [062]
;
Urbanisation et sociétés urbaines [102]
Description Géographique
BENIN ; COTONOU
Localisation
Fonds IRD [F B010078018]
Identifiant IRD
fdi:010078018
