THE THIAROYE AQUIFER IN SENEGAL: USABLE GROUNDWATER RESOURCES FOR DRINKING OR IRRIGATION

The Thiaroye drillings provided for a long time the supply of drinking water to the Dakar region. However, faced with the combined effects of salted bevel advancement and groundwater pollution, state authorities were led to stop their functioning. This led to a drop in the production of drinking water on the one hand, and favored, on the other hand, the recurrence of floods due to the rise of the groundwater level, resulting in the birth of another form of pollution: nitrification of the waters of the Thiaroye aquifer. This phenomenon has many and varied causes mainly related to a lack of waterproofness of septic tanks, the presence of a big cattle enclosure and a cemetery in the area. Their direct communication with the flush sheet is not without consequences on the immediate environment. Indeed, physicochemical analyzes carried out on the water samples taken from about ten piezometers have revealed that the level of the aquifer has, in some places, reached 500 mg/l far exceeding the drinking water standard of 50 mg/l fixed by WHO. As a result, this water has become unfit for human consumption. It is currently used in irrigation.