Douala, the economic capital of Cameroon with a population of about 2 million, has experienced repeated cholera epidemics in the past decade. Contaminated groundwater is the major source of cholera disease as residents use groundwater as major source of water for drinking and daily activities. Previous works showed that the leachate from household sewage system contaminated shallow groundwater in a local well, of which water depth is around 5-10 m. The major goal of the present study is to characterize the aquifer system in Douala by using geophysical techniques including time domain electromagnetic sounding (TDEM), magnetic resonance sounding (MRS), and electromagnetic method (EM) for better understanding of aquifer systems and developing safe groundwater resources in the region. As funded by the Geoscientist Without Borders (GWB) program, the study emphasized not only the scientific findings, but also capacity building to meet humanitarian needs in the region. The TDEM, MRS, and EM results show good agreement in depth and thickness of aquifers with the observed water bodies at nine different locations around Douala. The deeper aquifers in general have high MRS water content and decay time, but no indication of saltwater by TDEM. The existence of a deep aquifer may provide a good solution to develop a new well field for cleaner drinking water and to prevent future cholera outbreaks. The present complementary approach of geophysical techniques can be applicable to other similar urban settings in Africa as it produces good quality data under difficult urban settings with anthropogenic disturbance and natural electromagnetic noise
展开▼
