STORM-SURGE INDUCED WATER-QUALITY CHANGES IN AN UNCONFINED COASTAL AQUIFER SYSTEM

Numerous coastal communities rely heavily on groundwater for irrigation and potable water supply. The unconfined nature of most shallow coastal aquifers leaves them inherently vulnerable to water-quality degradation associated with infiltrating saltwater from tropical cyclone storm surges. While hydrogeological models can be used to predict water-quality changes due to such phenomena, these mathematical solutions are rarely verified by long-term, “before and after” monitoring data. One such data set exists for a site located on the U.S. Gulf Coast in an area that was inundated by a significant storm surge during Hurricane Katrina in August 2005. Water-quality data, collected quarterly from 1990 to the present in several wells that are screened in an unconfined surficial aquifer system, show baseline (pre-surge) groundwater conditions at the site, the initial impact immediately after the flooding event, and the eventual recovery of several key water-quality parameters to pre-surge levels.