Reconnaissance of the Diquini and Mariani springs and insights regarding the Massif de la Selle karst aquifer of Haiti

A reconnaissance was performed for Tunnel Diquini and Source Mariani in the metropolitan region of Port-au-Prince, Haiti, to address concerns of decreasing flows and to evaluate potential impacts of a proposed river diversion scheme in the study area. The tunnel and spring are the two largest water sources serving the Port-au-Prince municipal water system and discharge from the Massif de la Selle carbonate aquifer. Considering their significance and importance to the water security of the region, there are limited data or studies specific to the water sources. An introductory framework was established regarding the flow regimes, the origin of waters, and recharge dynamics of the sources. Field reconnaissance and stable-isotope, tracer, and chloride-mass-balance techniques were applied to strengthen the conceptual understanding of the water sources. Recharge to this portion of the Massif de la Selle carbonate aquifer is variable depending on monthly rainfall intensity and 3-7-year climatic cycles. Rather than a consistent long-term decreasing flow trend, a particularly intense period from 2007 through 2010 resulted in the highest flows on record, which have steadily recessed to historical norms in recent years. The recharge characteristics and catchment areas indicate that neither water source is connected to the River Momance; however, a connection to the River Froide is possible, particularly related to the tunnel. Finally, recharge rates and an estimate of renewable groundwater in the Massif de la Selle show the regional significance and importance of the carbonate aquifer for current supplies and future water development.