Modelling of the Infrabasaltic and Thiaroye aquifers — Dakar

01Background

The Dakar agglomeration relies on several strategic aquifers, including the Infrabasaltic and Thiaroye water tables, subject to significant abstraction pressures and water quality concerns.

DGPRE sought a coupled modelling tool to better understand the functioning of these systems and anticipate their evolution.

02Challenges

Securing drinking water supply to Dakar requires quantifying genuinely exploitable volumes and assessing the impact of abstraction scenarios on the resource.

The complexity of interactions between aquifers and the vulnerability of the Thiaroye water table made rigorous, calibrated modelling essential.

03Mission objectives

• Represent the coupled hydrodynamic functioning of the two aquifers
• Quantify water balance components
• Simulate abstraction and management scenarios
• Provide DGPRE with a sustainable decision-support tool

04Services provided by EAU-GEF

• Synthesis of geological, hydrogeological and abstraction data
• Construction and calibration of the coupled hydrodynamic model
• Simulation of abstraction and recharge scenarios
• Formulation of management recommendations
• Tool transfer and team support

05Approach & methodology

The model was constructed from a rigorous synthesis of available data, then calibrated against piezometric observations to ensure reliability.

Scenarios were explored comparatively to inform management trade-offs, without prejudging public decisions.

06Results & added value

The mission equipped DGPRE with a tool for understanding and forward-looking analysis of two key aquifers supplying Dakar.

It reinforces EAU-GEF's position in hydrodynamic modelling applied to drinking water supply security in an urban context.