Analyzing Tidal Fluctuations in the Big Pine Key Freshwater Lens with Time-Lapse Resistivity

Tucker, Nicole M.

doi:10.25148/etd.fi13080512

Cited by 3 publications

(8 citation statements)

References 18 publications

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“…From the formation factor as calculated by Tucker (2013), the porosity of the Miami oolite used in modeling is equal to approximately 33%, well within the bounds of previous estimates (Robinson, 1967;DiFrenna et al, 2008). Underestimations of the measured salinity at a well by the ERT-estimated value indicate a location where bedrock porosity is lower than this average, while overestimations indicate locations of higher bedrock porosity.…”

Section: Effects Of Bedrock Porosity On Ert-estimation Of Groundwatersupporting

confidence: 53%

“…For reference, the groundwater salinity measured at well B11 was found to vary by approximately 0.5 ppt over the course of the tidal cycle (Tucker, 2013) and at S31 by approximately 2 ppt (Ogurcak, unpublished data 2012). The increase in groundwater salinity observed after rain events at interior well locations, specifically at wells on the B1 and B2 transects ( Figure 4.4 and 4.5), could be the result of salts in the soil being flushed into the aquifer.…”

Section: Effects Of Precipitation and Et On The Freshwater Lensmentioning

confidence: 99%

“…Specific conductivity of the groundwater measured in wells during the surveys was converted to pore water resistivity and regressed against corresponding bulk resistivity output from the R2 inversions. As the formation factor for each island was similar and within each island's range of uncertainty, an average formation factor of 9.05 with a SD of 1.44 was used to calculate salinity (Tucker, 2013). Bulk resistivity values were converted to pore water resistivity by dividing by the above formation factor according to Archie's Law.…”

Section: Groundwater Salinity Calculationmentioning

confidence: 99%

“…A formation factor was calculated by Tucker (2013) for each island using orthogonal regression. Specific conductivity of the groundwater measured in wells during the surveys was converted to pore water resistivity and regressed against corresponding bulk resistivity output from the R2 inversions.…”

Section: Groundwater Salinity Calculationmentioning

confidence: 99%

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The Effect of Disturbance and Freshwater Availability on Lower Florida Keys’ Coastal Forest Dynamics

Ogurcak¹

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th century has been attributed to a combination of sea level rise and hurricane storm surge impacts, but the interactions between these two disturbances leading to forest decline are not well understood. The goal of my research was to assess their effects over a period spanning more than two decades, and to examine the relationships between these press and pulse disturbances and freshwater availability in pine rockland, hardwood hammock, and supratidal scrub communities. Impacts and recovery from two storm surges, Hurricanes Georges (1998) and Wilma (2005), were assessed with satellite-derived vegetation indices and multiple change detection techniques. Impacts were greater at lower elevations, and in hardwood hammock, spectral signatures indicative of plant stress and productivity returned to predisturbance levels within a few years. In pine rockland, impacts were predominately related to Hurricane Wilma, however, a similar return to pre-disturbance conditions was absent, suggesting that trajectories of disturbance recovery differed between the two communities. Long-term monitoring of forest composition, structure, and groundwater salinity showed that compositional shifts in the low shrub stratum were associated with ix salinization of the freshwater resource attributable to sea level rise. Throughout the course of twelve months of climate and groundwater monitoring (2011)(2012), groundwater salinity generally decreased in response to large precipitation events.Modeling of geophysical data indicated that groundwater salinity was an important predictor of community type. Isotopic analysis of δ 18 O in plant stem water and foliar δ 13 C was used to determine temporal and spatial patterns in water use and plant stress in two community dominants, slash pine, Pinus elliottii var. densa, and buttonwood, Conocarpus erectus. Both species relied heavily on groundwater, and plant stress was related to increasing groundwater salinity. The results of this work suggest that the interaction of press and pulse disturbances drive changes in community composition by causing mortality of salt-sensitive species and altering the freshwater resource.x forests that require freshwater inhabit a unique position on low-elevation limestone islands as glycophyte-dominated forests located in close proximity to saline water.Coastal forests in the greater Caribbean basin are also subject to periodic disturbance from hurricanes and tropical storms, but which typically are not stand-replacing events (Brokaw and Walker, 1991;Yih et al., 1991;Bellingham et al., 1992). Collectively, these forests are high in species diversity , 2006). These conditions would favor a combination of disturbance, 2 drought, and salinity tolerant species, as groundwater salinity increases (Guha and Panday, 2012) and coastal forests are exposed more frequently to major storms, with shrinking recovery periods between such events (Lugo, 2000). Additionally, the interaction of press and pulse events will increase the likelihood of surface inundation by salt w...

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Section: Effects Of Bedrock Porosity On Ert-estimation Of Groundwatersupporting

confidence: 53%

Section: Effects Of Precipitation and Et On The Freshwater Lensmentioning

confidence: 99%

Section: Groundwater Salinity Calculationmentioning

confidence: 99%

Section: Groundwater Salinity Calculationmentioning

confidence: 99%

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The Effect of Disturbance and Freshwater Availability on Lower Florida Keys’ Coastal Forest Dynamics

Ogurcak¹

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“…Because resistivity is often dependent on formation porosity and pore fluid salinity, ERT is a powerful tool to characterize the spatial and temporal changes in aquifers (Binley and Kemna 2005). ERT methods have been widely used in monitoring the dynamics of salt water intrusion (De Franco et al 2009;Goebel et al 2017), tidal disturbance (Tucker 2013;Ogurcak 2015;Huizer et al 2017), and subsurface contamination (Kemna et al 2002;Simyrdanis et al 2018;Caterina et al 2017;Rosales et al 2012). Huizer et al (2017) investigated the impact of tides and storm surges on coastal groundwater on the Dutch Coast and simulated the salinity change in the coastal aquifer.…”

Section: Communicated By David Reide Corbettmentioning

confidence: 99%

The Effect of Hurricane Irma Storm Surge on the Freshwater Lens in Big Pine Key, Florida using Electrical Resistivity Tomography

Kiflai

Whitman

Ogurcak

et al. 2019

Estuaries and Coasts

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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.

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Geophysical Characterization in the Shallow Water Estuarine Lakes of the Southern Everglades, Florida

et al. 2022

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Anthropogenic activities have greatly modified freshwater flows through Everglades National Park (ENP) such that saltwater has intruded extensively inland from the coastline, causing coastal lakes and their ecosystems to be exposed to varying salinity conditions. The Comprehensive Everglades Restoration Plan (CERP) makes an effort to restore the quantity, quality, timing, and distribution of freshwater flow in ENP with a goal of reducing salinity conditions within the coastal communities and adjacent estuaries. An understanding of the temporal and spatial variations of surface water and shallow groundwater salinity in the coastal lakes of ENP is needed to evaluate restoration efforts. Geophysical surveys were conducted between 2016 to 2019 using electrical resistivity and electromagnetic (EM) methods in the coastal lakes of ENP. A mean local formation factor of 10.7 ± 1.8 was calculated for the region by comparing the lakes’ bottom formation inverted electrical resistivity soundings with coincident pore water resistivity measured in groundwater wells. The conductivity of surface and groundwater increased during the dry season, reflecting decreased precipitation, increased evapotranspiration, and the increasing influence of saline water from Florida Bay. Spatially, salinity in the lakes increased from west to east in the surface water with an opposite trend observed in the shallow groundwater. Along the south to north inland direction, the salinity of both surface water and groundwater decreased. This study demonstrates that floating electrical resistivity and EM methods can characterize the subsurface formation resistivity and describe temporal and spatial patterns of surface and shallow groundwater conductivity.

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Analyzing Tidal Fluctuations in the Big Pine Key Freshwater Lens with Time-Lapse Resistivity

Cited by 3 publications

References 18 publications

The Effect of Disturbance and Freshwater Availability on Lower Florida Keys’ Coastal Forest Dynamics

The Effect of Disturbance and Freshwater Availability on Lower Florida Keys’ Coastal Forest Dynamics

The Effect of Hurricane Irma Storm Surge on the Freshwater Lens in Big Pine Key, Florida using Electrical Resistivity Tomography

Geophysical Characterization in the Shallow Water Estuarine Lakes of the Southern Everglades, Florida

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