Characterization And Modeling Of Seawater Intrusion In An Aquifer Along The West Coast Of Barbados

A series of non-invasive geophysical surveys was performed at a pilot site on Barbados as part of<br>a geologic and hydrologic characterization effort to develop a long-term sustainable management<br>framework for karst aquifers along the island’s west coast. The geophysical surveys included timedomain<br>electromagnetic soundings, Schlumberger D.C. resistivity depth soundings, high-resolution<br>dipole-dipole profiles for tomographic imaging, and shallow ground conductivity profiles. Results<br>from the surveys showed (i) a relatively thin freshwater lens, with the transition zone between the<br>freshwater and the underlying seawater being relatively thin, (ii) the presence of several potential<br>groundwater flow conduits, (iii) the contact between the overlying permeable limestone unit and the<br>underlying low permeability sedimentary units, and (iv) the near-surface contact between the<br>limestone units and beach and dune deposits. These observations were used to develop and<br>implement a conceptual model of groundwater flow and seawater intrusion for the site. Preliminary<br>results from the hydrologic model compare favorably to an electrical resistivity cross-section<br>developed for a portion of the site.