TIME LAPSE ELECTRICAL RESISTIVITY TOMOGRAPHY OF NEARSHORE GROUNDWATER FROM A TROPICAL CARBONATE ISLAND
Comparing apparent resistivity for each dataset against the initial dataset, we demonstrate that total apparent resistivity decreased sequentially to a minimum of 11.5% below the initial configuration during the measurement period. The timing of the resistivity changes suggests that tidal pumping of seawater into the nearshore groundwater reaches a maximum somewhere between 1.5 and 3 hours after high tide. Inversion models created in R2 and graphed in Surfer illustrate the spatial arrangement of changes to earth resistivity during the tidal cycle. Creating difference plots between each modeled dataset and the initial modeled data reveal that changes to resistivity are restricted to the upper 10 meters of the transect and expectedly more pronounced closer to the shoreline.