GROUNDWATER MANAGEMENT TO PREVENT SALTWATER ENCROACHMENT, HACIENDA BARU COSTA RICA
In 2007 Baylor personnel conducted projects at Hacienda Baru to obtain data on water consumption, to make recommendations for upgrading wastewater treatment, and to install water meters to more accurately quantify water use in the area.
Hacienda Baru relies on shallow groundwater from a spring in the nearby hills and one well completed in the coastal plain aquifer. The seasonality of rainfall in Costa Rica is split into a dry season (January to March) and a rainy season (August - October). During the rainy season the spring that supplies Hacienda Baru is adequate due to the combination of increased recharge and less demand from the fewer visitors. However, during the dry season the flow from the spring may no longer be sufficient and the well is used to supplement as a backup source for freshwater when demand is higher and the spring flow is less.
Wells that operate in shallow coastal aquifers are prone to saltwater encroachment or up-coning that may result from over-pumping. This problem has been observed in the Pacific coastal aquifers of Costa Rica. If the saltwater/freshwater interface changes, floral and faunal environments, as well as fresh water resources may be damaged.
In continuation of the work done in 2007 studies have been conducted on the well at Hacienda Baru. Shallow piezometers were augured to assess the electrical conductance of the shallow groundwater in a vertical and horizontal extent at Hacienda Baru. A pressure transducer and data logger were installed on one of the shallow piezometers to measure seasonal fluxes. These data are being used to help manage the water at Baru in order to monitor the possibility of lateral salt water encroachment and up-coning. The use of remotely sensed imagery is proposed to monitor any changes in vegetation health. Results should be applicable to other areas along the Pacific coast of Costa Rica and similar hydrogeological settings.