Assessing the "superposed" effects of storm surge from a Category 3 hurricane and continuous sea-level rise on saltwater intrusion into the surficial aquifer in coastal east-central Florida (USA).

Saltwater intrusion into the surficial aquifer in coastal east-central Florida (USA) due to the effects of storm surges from tropical cyclones and continuous sea-level rise is a detrimental issue resulting in groundwater quality deterioration and bio-diverse ecosystem degradation. In this study, groundwater flow and salinity transport models using SEAWAT are developed for quantifying the "superposed" effects of storm surge (SS) from a Category 3 hurricane (Hurricane Jeanne which hit the Florida Atlantic coast on September 24-27, 2004) and continuous sea-level rise (SLR) on saltwater intrusion (SWI) into the surficial aquifer in coastal east-central Florida from the year of 2004 to 2024, and the simulated time-variant extent of SS- and SLR-induced landward migration of saline groundwater is compared for determination of whether the effects of SS from a Category 3 hurricane or continuous SLR on SWI are more significant. Results indicate that (1) the effects of SS are more significant than the effects of SLR within the first 12, 10, or 9 years after its occurrence date if sea level rises in low, mid, or high rate; (2) the effects of SS are more significant than the effects of SLR if SS occurs at least once within its return period (8-12 years); and (3) the maximum effects of SS are "equivalent" to the effects of the 95-year SLR, 45-year SLR, or 28-year SLR if sea level rises to 0.3 m in low, mid, or high rate. The outcome of this study warns public to pay more attention to the detrimental "superposed" effects of SS and SLR on SWI into the surficial aquifer in coastal east-central Florida.