Factors Influencing the Shallow Groundwater Quality in Four Districts with Different Characteristics in Urban Area (Douala, Cameroon)

Abstract

This study examines groundwater samples from four areas under different conditions. Variations amongst the areas are due to the distinct topography, demographics, and socio-economic activities. A qualification of the groundwater using the following parameters; pH, electric conductivity and nitrate analysis yielded results depicting the deplorable state of the unconfined aquifer; which is even worst in the densely populated and low-lying areas. These unfavorable conditions are present in the older districts (Bependa and Ndogbong) compared to the younger and least populated (urbanized) districts (Ndogpassi and Logpom). The poor quality of groundwater could be due to contamination by sewage from latrines and surface discharges. Nevertheless, nitrate contents (>241 mg/l) in these districts indicate that pollution has not reached the alarming levels observed in other West African cities (nitrates > 400 mg/l). Relatively low concentrations of nitrate in groundwater of the studied areas could be due to volatilization phenomena common in the unconfined aquifers in Douala. We however remarked that most of the studied wells are not used as drinking water, because they present particular health risks to humans.