Hydrogeophysical Characterization and Imaging in the Mangrove Lakes Region of Everglades National Park and Big Pine Key, Florida, USA

Authors

Michael Eyob KiflaiFollow

Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Earth Systems Science

First Advisor's Name

Dean Whitman

First Advisor's Committee Title

committee chair

Second Advisor's Name

René M. Price

Second Advisor's Committee Title

committee member

Third Advisor's Name

Assefa M. Melesse

Third Advisor's Committee Title

committee member

Fourth Advisor's Name

Pete E. Markowitz

Fourth Advisor's Committee Title

committee member

Keywords

Environmental indicators and impact assessment, environmental monitoring, geology, geophysics and seismology, natural resources and conservation, hydrology

Date of Defense

7-2-2020

Abstract

Coastal groundwater aquifers are susceptible to saltwater intrusion from natural and anthropogenic sources. Everglades National Park (ENP) has been adversely impacted by past human activities that altered freshwater flow through the system. In Big Pine Key (BPK), the flat and low-lying topography less than 2m makes the freshwater lens vulnerable to tidal and storm surge events. This study investigated different inversion scenarios and used Electrical Resistivity Tomography (ERT) and Electromagnetic (EM) survey to characterize the spatial and temporal change of the groundwater chemistry and image the aquifers. In Big Pine Key, Hurricane Irma made landfall as a category 4 storm with storm surge heights in excess of 2 m. 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 8 to 11 months (May/December 2018) 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. These data showed 40 and 70 % recovery of the freshwater lens in May and December 2018 and most pronounced in the lower elevation of the profiles.

In the Mangrove lakes of the Everglades, a constrained water depth (fixed water layer thickness) inversion model is selected as an effective inversion approach. In our study, we estimated a formation factor 10.7 with a standard deviation of 1.81 by comparing the bulk resistivity measured using a floating Dipole-Dipole array and coincident conductivity data from the wells. Between, 2016 to 2019, the spatial salinity variation on the lakes showed west to east increase in surface water salinity and west to east decrease in groundwater salinity. In addition, the salinity of the surface water and groundwater increased from North to South and suggested freshening of the groundwater and may reflect the effects of increased flow caused by restoration efforts.

Identifier

FIDC009158

ORCID

https://orcid.org/0000-0001-7662-4563

Previously Published In

Kiflai, M.E., Whitman, D., Ogurcak, D.E. et al. The Effect of Hurricane Irma Storm Surge on the Freshwater Lens in Big Pine Key, Florida using Electrical Resistivity Tomography. Estuaries and Coasts 43, 1032–1044 (2020). https://doi.org/10.1007/s12237-019-00666-3

Recommended Citation

Kiflai, Michael Eyob, "Hydrogeophysical Characterization and Imaging in the Mangrove Lakes Region of Everglades National Park and Big Pine Key, Florida, USA" (2020). FIU Electronic Theses and Dissertations. 4475.
https://digitalcommons.fiu.edu/etd/4475