Current Search:  Ground penetrating radar (x)

View All Items

  • CSV Spreadsheet
(1 - 6 of 6)
Multi-scale characterization of dissolution structures and porosity distribution in the upper part of the Biscayne aquifer using ground penetrating radar (GPR)
Title
Multi-scale characterization of dissolution structures and porosity distribution in the upper part of the Biscayne aquifer using ground penetrating radar (GPR).
Creator
Mount, Gregory J., Comas, Xavier, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Geosciences
Abstract/Description
The karst Biscayne aquifer is characterized by a heterogeneous spatial arrangement of porosity, making hydrogeological characterization difficult. In this dissertation, I investigate the use of ground penetrating radar (GPR), for understanding the spatial distribution of porosity variability in the Miami Limestone presented as a compilation of studies where scale of measurement is progressively increased to account for varying dimensions of dissolution features. In Chapter 2, GPR in zero...
Show moreThe karst Biscayne aquifer is characterized by a heterogeneous spatial arrangement of porosity, making hydrogeological characterization difficult. In this dissertation, I investigate the use of ground penetrating radar (GPR), for understanding the spatial distribution of porosity variability in the Miami Limestone presented as a compilation of studies where scale of measurement is progressively increased to account for varying dimensions of dissolution features. In Chapter 2, GPR in zero offset acquisition mode is used to investigate the 2-D distribution of porosity and dielectric permittivity in a block of Miami Limestone at the laboratory scale (< 1.0 m). Petrophysical models based on fully saturated and unsaturated. water conditions are used to estimate porosity and solid dielectric permittivity of the limestone. Results show a good correspondence between analytical and GPR-based porosity estimates and show variability between 22.0-66.0 %. In Chapter 3, GPR in common offset and common midpoint acquisition mode are used to estimate bulk porosity of the unsaturated Miami Limestone at the field scale (10.0-100.0 m). Estimates of porosity are based on the assumption that the directly measured water table reflector is flat and that any deviation is attributed to changes in velocity due to porosity variability. Results show sharp changes in porosity ranging between 33.2-60.9 % attributed to dissolution areas. In Chapter 4, GPR in common offset mode is used to characterize porosity variability in the saturated Biscayne aquifer at 100-1000 m field scales. The presence of numerous diffraction hyperbolae are used to estimate electromagnetic wave velocity and asses both horizontal and vertical changes in porosity after application of a petrophysical model. Results show porosity variability between 23.0-41.0 % and confirm the presence of isolated areas that could serve as enhanced infiltration or recharge. This research allows for the identification and delineation areas of macroporosity areas at 0.01 m lateral resolution and shows variability of porosity at different scales, reaching 37.0 % within 1.3 m, associated with areas of enhanced dissolution. Such improved resolution of porosity estimates can benefit water management efforts and transport modelling and help to better understand small scale relationships between ground water and surface water interactions.
Show less
Date Issued
2014
PURL
http://purl.flvc.org/fau/fd/FA00004143
Subject Headings
Ground penetrating radar, Limestone -- Florida -- Miami Dade County -- Analysis, Physical geology, Sedimentary basins -- Florida -- Biscayne Aquifer, Sedimentation analysis
Format
Document (PDF)
Variations of soil physical properties across different habitats using GPR
Title
Variations of soil physical properties across different habitats using GPR.
Creator
Leung, Tania, Graduate College
Date Issued
2013-04-12
PURL
http://purl.flvc.org/fcla/dt/3361323
Subject Headings
Soil physics, Ground penetrating radar, Habitat (Ecology)
Format
Document (PDF)
Biogenic gas dynamics in peat soil blocks using ground penetrating radar: a comparative study in the laboratory between peat soils from the Everglades and from two northern peatlands in Minnesota and Maine
Title
Biogenic gas dynamics in peat soil blocks using ground penetrating radar: a comparative study in the laboratory between peat soils from the Everglades and from two northern peatlands in Minnesota and Maine.
Creator
Cabolova, Anastasija., Charles E. Schmidt College of Science, Department of Physics
Abstract/Description
Peatlands cover a total area of approximately 3 million square kilometers and are one of the largest natural sources of atmospheric methane (CH4) and carbon dioxide (CO2). Most traditional methods used to estimate biogenic gas dynamics are invasive and provide little or no information about lateral distribution of gas. In contrast, Ground Penetrating Radar (GPR) is an emerging technique for non-invasive investigation of gas dynamics in peat soils. This thesis establishes a direct comparison...
Show morePeatlands cover a total area of approximately 3 million square kilometers and are one of the largest natural sources of atmospheric methane (CH4) and carbon dioxide (CO2). Most traditional methods used to estimate biogenic gas dynamics are invasive and provide little or no information about lateral distribution of gas. In contrast, Ground Penetrating Radar (GPR) is an emerging technique for non-invasive investigation of gas dynamics in peat soils. This thesis establishes a direct comparison between gas dynamics (i.e. build-up and release) of four different types of peat soil using GPR. Peat soil blocks were collected at peatlands with contrasting latitudes, including the Everglades, Maine and Minnesota. A unique two-antenna GPR setup was used to monitor biogenic gas buildup and ebullition events over a period of 4.5 months, constraining GPR data with surface deformation measurements and direct CH4 and CO2 concentration measurements. The effect of atmospheric pressure was also investigated. This study has implications for better understanding global gas dynamics and carbon cycling in peat soils and its role in climate change.
Show less
Date Issued
2010
PURL
http://purl.flvc.org/FAU/2974433
Subject Headings
Wetland ecology, Wetland ecology, Wetland ecology, Gas dynamics, Soil permeability, Ground penetrating radar, Porous materials, Fluid dynamics
Format
Document (PDF)
Use of Ground Penetrating Radar (GPR) in a Study on Beach Morphodynamics at Red Reef Beach, Boca Raton, Florida
Title
Use of Ground Penetrating Radar (GPR) in a Study on Beach Morphodynamics at Red Reef Beach, Boca Raton, Florida.
Creator
Camara dos Santos Porto, Sabrina, Briggs, Tiffany Roberts, Comas, Xavier, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Geosciences
Abstract/Description
The internal architecture of a beach system can provide clues into the processes involved in its formation, including depositional processes, and/or driving mechanisms (Billy et al., 2014). Several unique events such as cold fronts or Hurricane Irma caused conditions that resulted in erosion and accretion changes in Red Reef Beach - Boca Raton, throughout the year of 2017. Since the lateral extent of these changes is difficult to evaluate using traditional methods such as coring, a Ground...
Show moreThe internal architecture of a beach system can provide clues into the processes involved in its formation, including depositional processes, and/or driving mechanisms (Billy et al., 2014). Several unique events such as cold fronts or Hurricane Irma caused conditions that resulted in erosion and accretion changes in Red Reef Beach - Boca Raton, throughout the year of 2017. Since the lateral extent of these changes is difficult to evaluate using traditional methods such as coring, a Ground Penetrating Radar (GPR) was tested, which allows for a good lateral resolution (cm scale), to image the distribution and evolution of these sediments. The objectives of this study were to 1) explore the lateral variability in the internal architecture of sediments in Red Reef beach in Boca Raton (FL) using an array of ground penetrating radar (GPR) measurements constrained with coring and sediment analysis; 2) explore how dynamics of erosion and accretion induced by changes in wave activity and related to tide variation and storm events, may affect surface topography and the sedimentary internal architecture of beach deposits, using RTK GPS and GPR time-lapse measurements; 3) to explore changes in the lateral extent of the freshsaltwater interface along the beach profile in relation to tide variation and storm events. Reflectors identified in the GPR images showed some evidence of erosional and accretionary surfaces preserved in Red Reef beach. These measurements were repeated over time coinciding with certain events (such as Hurricane Irma) to explore their effects in terms of sediment erosion and accretion as reflected in changes in topography (using time-lapse GPS-RTK measurements), and changes in the internal sedimentary architecture (using time-lapse GPR measurements). The datasets collected also revealed the temporal evolution of the salt-freshwater interface, showing how the lateral extent of saltwater saturated sediment (inferred from areas of GPR signal attenuation along the profiles) evolved over time. This study shows the potential of GPR to provide information about beach sediment processes and dynamics at resolutions beyond traditional measurements (such as coring). It also shows the importance of combining methods that are complementary, such as the use of RTK GPS to explore changes in topography, and GPR that provides information on subsurface sedimentary architecture and the mechanism of change such as post-storm recovery. This study has implications for better understanding changes in coastal sedimentary deposits and processes, both at the subsurface, particularly after high-energy events, such as hurricanes, that result in rapid changes in erosion and/or accretion of sediments.
Show less
Date Issued
2017
PURL
http://purl.flvc.org/fau/fd/FA00005947
Subject Headings
Dissertations, Academic -- Florida Atlantic University, Beaches--Florida, Ground penetrating radar., Sediments (Geology)--Analysis.
Format
Document (PDF)
Mapping the Fresh-Saltwater Transition Zone Across the Beach Environment Using Ground-Penetrating Radar (GPR)
Title
Mapping the Fresh-Saltwater Transition Zone Across the Beach Environment Using Ground-Penetrating Radar (GPR).
Creator
Becker, Joseph Michael, Roberts Briggs, Tiffany, Comas, Xavier, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Geosciences
Abstract/Description
As sea level rises, saltwater migration can threaten coastal ecosystems and beach-dune environments, which negatively impacts coastal flora. This study uses ground penetrating radar (GPR) to evaluate the spatiotemporal variability of saltwater migration in the near shore at high lateral resolution (i.e. cm) by using daily micro tidal cycles as analogs to infer saltwater migration. Time-lapse GPR profiles were collected at low and high tide capturing phase lags of the tidal flux through...
Show moreAs sea level rises, saltwater migration can threaten coastal ecosystems and beach-dune environments, which negatively impacts coastal flora. This study uses ground penetrating radar (GPR) to evaluate the spatiotemporal variability of saltwater migration in the near shore at high lateral resolution (i.e. cm) by using daily micro tidal cycles as analogs to infer saltwater migration. Time-lapse GPR profiles were collected at low and high tide capturing phase lags of the tidal flux through different substrates. GPR measurements were collected at two sites in Miami with contrasting lithologies: a) Crandon Park, composed of unconsolidated sand; and b) the Barnacle Historic State Park, composed of the Miami Limestone Formation. Laboratory-scale GPR measurements were collected over samples mimicking field conditions. The results may be helpful to identify regions vulnerable to saltwater migration in the near shore based on lithological variability, and to mitigate negative impacts for flora in beach-dune habitats during sea level rise.
Show less
Date Issued
2019
PURL
http://purl.flvc.org/fau/fd/FA00013183
Subject Headings
Ground penetrating radar, Saltwaters, Seashore ecology, Coastal ecology
Format
Document (PDF)
Investigating variability of biogenic gas dynamics in peat soils using high temporal frequency hydrogeophysical methods
Title
Investigating variability of biogenic gas dynamics in peat soils using high temporal frequency hydrogeophysical methods.
Creator
Wright, William J., Charles E. Schmidt College of Science, Department of Geosciences
Abstract/Description
Peat soils are known to be a significant source of atmospheric greenhouse gasses. However, the releases of methane and carbon dioxide gasses from peat soils are currently not well understood, particularly since the timing of the releases are poorly constrained. Furthermore, most research work performed on peatlands has been focused on temperate to sub-arctic peatlands, while recent works have suggested that gas production rates from low-latitude peat soils are higher than those from colder...
Show morePeat soils are known to be a significant source of atmospheric greenhouse gasses. However, the releases of methane and carbon dioxide gasses from peat soils are currently not well understood, particularly since the timing of the releases are poorly constrained. Furthermore, most research work performed on peatlands has been focused on temperate to sub-arctic peatlands, while recent works have suggested that gas production rates from low-latitude peat soils are higher than those from colder climates. The purpose of the work proposed here is to introduce an autonomous Ground Penetrating Radar (GPR) method for investigating the timing of gas releases from peat soils at the lab scale utilizing samples originating from Maine and the Florida Everglades, and at the field scale in a Maine peatland. Geophysical data are supported by direct gas flux measurements using the flux chamber method enhanced by timelapse photography, and terrestrial LiDAR (TLS) monitoring surface deformation.
Show less
Date Issued
2013
PURL
http://purl.flvc.org/fcla/dt/3361256
Subject Headings
Gas dynamics, Wetland ecology, Soil permeability, Estuarine sediments, Ground penetrating radar, Hydrogeology, Geophysics
Format
Document (PDF)