Honors College Theses

Publication Date

11-29-2017

Major

Geology (B.S.)

Document Type and Release Option

Thesis (open access)

Faculty Mentor

Dr. Robert Kelly Vance

Abstract

Geophysical tools were used to investigate potential structural and stratigraphic pathways of the salt water intrusion that is affecting the surficial aquifer on St. Catherines Island, Georgia. Ground penetrating radar (GPR) is a geophysical tool that uses electromagnetic waves to view the subsurface. GPR is used for a variety of applications stratigraphically, biologically, and anthropogenically. GPR electromagnetic waves react to changes in density and composition and type and percentage of pore fluids in sediment and rock. GPR waves also react to interfaces including fractures and faults. GPR waves exhibit attenuation and decreased return signal in materials such as clay. Fresh water saturation of sand also attenuates GPR waves and saline waters may result in total loss of return signal. Therefore, it may be possible to use GPR to detect where salt water intrusion is occurring on the island and structural and stratigraphic pathways that permit it. Here we use a MALÅ ground-penetrating radar to determine where salt water is intruding into the shallow wells that have been dug on St. Catherines Island. We also use this data to create a more complete stratigraphical picture of the island. We found structural conduits in the shallow aquifer that may permit salt water intrusion. The ability to locate conduits is important because it allows for a greater understanding of salt water intrusion in the Georgia Coastal aquifers.

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