Benin, West Africa

Overview

In the heavily populated coastal city of Cotonou, the sustainability of fresh water supplies is under severe threat from saltwater intrusion driven by coastal development, groundwater overuse, and sea-level rise. For a city that relies heavily on groundwater for drinking and agriculture, this poses a critical challenge to long-term water security and public health.

This GWB-funded project aimed to map and characterize the Godomey aquifer system to better understand the extent of saltwater intrusion and guide strategies for sustainable groundwater management.of the CSM Humanitarian Engineering and Science: Geophysics Master’s Program.

Approach

The project team deployed seismic reflection techniques to delineate the major hydrogeologic units of the Godomey aquifer system. Complementary electrical resistivity and electromagnetic (EM) surveys were used to image the freshwater–saltwater interface, providing a detailed picture of how saline water is encroaching inland.

Data were integrated into geologic and hydrologic models that help local decision-makers plan well placements and manage extraction rates to protect remaining freshwater reserves.

Impact

Produced the first detailed subsurface map of the Godomey aquifer’s freshwater–saltwater boundary.

Delivered actionable data to local water agencies to inform sustainable resource management.

Supported training of Beninese geoscientists and students in advanced geophysical techniques.

Strengthened the region’s capacity to monitor and mitigate saltwater intrusion, enhancing resilience to climate change.