Numerical computation of hurricane-induced saltwater intrusion on fresh groundwater availability in peninsular Florida under different climate scenarios
MetadataShow full item record
Climate change is generally expected to influence hurricane behaviour by supercharging hurricanes through increasingly warmer and moister environments (Trenberth et al., 2018). Climate change projections indicate relatively more extreme hurricane events (Knutson et al., 2015), higher storm-surge values (Lin et al., 2012) and suggest that contemporary storm surge hazard zones could extend further inland while taking sea-level rise into account (Frazier et al., 2010). As storm surge can induce saltwater intrusion into the groundwater system, climate change can threaten fresh groundwater availability in already vulnerable coastal aquifer systems even more. For example, coastal aquifers in south-eastern Florida have been put under increasing pressure due to saltwater intrusion (Sonenshein, 1997). As Florida is more likely to get hit by hurricanes than any other state in the United States (Malmstadt et al., 2009), storm surge increases could have far-reaching consequences in Florida. Due to the vital importance of fresh groundwater availability for population, agriculture and nature, it is important to gain knowledge on the effect of possible climate scenarios on fresh groundwater availability. In this thesis, the following main research question is addressed: How does hurricane-induced saltwater intrusion affect fresh groundwater availability in peninsular Florida under different climate scenarios? To answer this question, a three-dimensional variable-density groundwater flow and coupled salt transport model was developed in iMOD-SEAWAT (i.e. SEAWAT in an iMOD setting; the GUI of MODFLOW by Deltares (Vermeulen et al., 2018)), and climate scenarios were simulated that consist of different hurricane intensities, peak rainfall rates and sea-level rise projections. Model simulations indicate that hurricane intensity has the most pronounced effect on saltwater intrusion and is amplified when sea-level rise projections are considered. Also, the study shows that the surficial aquifer system can nearly always recover in time before another hurricane and related storm surge will strike the shore. However, if the hurricane return period becomes smaller than the flushing period due to climate change, the surficial aquifer system will be put under increasing pressure. Then, this research indicates that strategies that mitigate and reverse saltwater intrusion should be considered timely and carefully. Due to limitations regarding the hurricane-induced storm surge calculations and the hydrogeological model, the findings of this research should be used as an indication of the impact of climate scenarios on fresh groundwater availability. Future research should investigate whether the findings can be reproduced with an accurate storm surge model. Furthermore, climate change effects on hurricane return periods for vulnerable areas should be analysed too.