The Effect of Hurricane Irma Storm Surge on the Freshwater Lens in Big Pine Key, Florida using Electrical Resistivity Tomography
Animals and plants on low elevation oceanic islands often rely on a thin lens of fresh groundwater and this lens is vulnerable to seawater contamination from storm surge. Documentation of the impact of the storm surge on the freshwater lens and its subsequent recovery is limited. In September 2017, Hurricane Irma made landfall in the Florida Keys as a category 4 storm with storm surge heights in excess of 2 m. This study used Electrical Resistivity Tomography (ERT) to investigate the effect of the storm surge on the freshwater lens of Big Pine Key, FL. The study compared ERT images along three profiles ranging between 220 and 280 m length collected in 2011 with post storm data collected about 3 to 4 months (November 2017/January 2018) and eight (May 2018) months after Irma. The post storm data documented that the storm surge impacted the freshwater lens on all three profiles with low resistivity (i.e., high salinity) zones in the upper 2 m of the groundwater. The increase in salinity was most pronounced in the lower elevations of the profiles. The May 2018 data were collected immediately after 2 weeks of intense precipitation. These data showed 40% recovery of the freshwater lens, most pronounced in the lower elevation of the profiles. This suggests that both the impact of storm surge and the freshwater recovery due to precipitation are most pronounced in low elevation regions where both saline and freshwater can collect at the surface.
KeywordsERT Salinity Inversion Hurricane Irma
We wish to extend our appreciation to Andrew Binley for making R2 software freely available and Nicole M. Tucker, Alejandro Garcia and Himadri Biswas who contributed to the data acquisition. Comments by the anonymous reviewers and editors substantially improved the manuscript. This is contribution number 931 from the Southeast Environmental Research Center in the Institute of Water and Environment at Florida International University.
This research was funded by the National Fish and Wildlife Foundation and administered by the US Fish and Wildlife Service (USFWS) National Key Deer Refuge (Cooperative Agreement Award No. F18AC00088).
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