The Caribbean Yucatan aquifer is a density-stratified karstified coastal carbonate aquifer comprising a fresh water lens (FWL) overlying a saline water zone (SWZ). Cave diving exploration has revealed more than 500 km of flooded cave passage that extend from coastal springs through to at least a distance of 10 km inland. A regional dataset of fresh and saline water temperature and specific electrical conductance (SEC) has been compiled through surface and cave diving observations. The SEC of the FWL from 9 to 3.4 km inland increases very slowly with a gradient of 0.35 ± 0.14 mS/cm per kilometre from a low of 2.48 mS/cm at 8.67 km inland, however higher gradients of SEC increase occur closer to the coast (2.11 ± 0.31 mS/cm per kilometre, from 4 to 0.4 km) due to increased mixing with saline water. Whilst the SEC of the SWZ in conduits is spatially consistent (50.00 ± 1.25 mS/cm, n=20) reflecting the characteristics of the marine source water (50.55 ± 0.42, n=4), the temperature of the SWZ decreases from a high of 27 - 28 oC near the coast to ~25.5 oC at 20 km inland. It is therefore suggested that warm shallow Caribbean sea water is moving rapidly to at least 9 km inland though the conduit systems. This suggestion is supported by results from dye tracing and also flow data from oceanographic current meters. Our results suggest that in some coastal carbonate aquifers the conventional model that the fresh water outflow entrains a parallel coastward saline flow with compensatory saline inflow at depth, may not apply. Our results also suggest geothermal heating may not be the major drive for SWZ circulation as it is in other carbonate aquifers such as the Biscayne aquifer of Florida.
|State||Published - 2006|
|Event||Limestone Hydrogeology Meeting of the Geological Society - Bristol, UK|
Duration: Jan 1 2006 → …
|Conference||Limestone Hydrogeology Meeting of the Geological Society|
|Period||1/1/06 → …|