Isotopic study of the groundwater of the flatland of Cul-de-Sac, Republic of Haiti

The main aquifer of the flatland of the Cul-de-Sac is made up of a multiple alluvial formation which has accumulated in the quaternary on the graben between two anticlinorius of karstified limestone of the eocenic age. The environmental isotopes clearly show the origin and the preferential course of water circulation in the aquifer and its relation with the karstic system. The main source of recharge is the river Gris. The contribution of the north karst is of little importance. The origin of the salinity of the groundwater in the septentrional region of the flatland and the region of Port-au-Prince has also been investigated. The salt water is slightly enriched with heavy isotopes with respect to fresh groundwater, not showing any deviation from the straight line of meteoric waters. These waters could be derived from superficial waters put under evaporation under the condition of relative high humidity or from precipitations of another period which have been enriched with heavy isotopes with respect to the current precipitations. In the area of Port-au-Prince the salinity of the groundwater is the result of seawater intrusion as a consequence of intensive exploitation. 7 refs, 7 figs, 6 tabs