Term of Award

Summer 2024

Degree Name

Master of Science, Applied Geography

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Geology and Geography

Committee Chair

Jacque Kelly

Committee Member 1

Munshi Rahman

Committee Member 2

John Carroll

Abstract

Florida Bay, situated at the southern tip of Everglades National Park and underlain by the Miami Limestone formation, is an ecosystem of global significance. Over the past century, the bay has faced threats such as droughts, seagrass mortality, and hypersalinity. Despite various studies and management efforts, the dynamics of submarine groundwater discharge (SGD) in the region remain underexplored. Given that SGD plays a significant role in the chemical dynamics of coastal ecosystems, it warrants thorough investigation. This study aims to characterize the spatial and temporal patterns of SGD in Florida Bay by surveying three basins – Rankin, Whipray, and Rabbit Key – from 2021 to 2024, covering both wet and dry seasons. Using electrical resistivity tomography (ERT) with a dipole-dipole array, I mapped marine resistivity, revealing low bulk resistivity values (0.1 - 4.0 Ωm) across the study area. Elevated resistivity anomalies upwelling from the limestone units were interpreted as possible SGD zones, prompting in-situ radon-222 and salinity measurements for validation. The hypersaline nature of groundwater, with concentrations up to 45 ppt in Rankin Basin, indicates the SGD is recirculated seawater. The identification of pockets of saline SGD and no fresh SGD underscored the difficulty in using ERT method in areas of minimal salinity variations and low resistivity ranges with respect to groundwater. I postulate that the geophysical anomalies primarily stem from subsurface petrophysical properties rather than groundwater chemistry. This study enriches our understanding of Florida Bay's hydrology and informs future scientific research and management efforts.

Research Data and Supplementary Material

No

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