The effect of eustatic sea-level changes on saltwater-freshwater relations in the northern Atlantic Coastal Plain

Meisler, Harold; Leahy, P. P.; Knobel, LeRoy L.

doi:10.3133/wsp2255

Cited by 16 publications

(2 citation statements)

References 9 publications

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“…To mitigate the increasing demand on groundwater systems, offshore freshened groundwater (OFG) has been proposed as an alternative source of potable water (Bakken et al, 2012). The key emplacement mechanisms for OFG include present-day meteoric recharge from the onshore portion of the aquifer (Michael et al, 2016;Paldor et al, 2020) and/or meteoric recharge of shelf areas that were exposed during sea-level lowstands (Meisler et al, 1984). In the case of the latter, emplaced groundwater migrated landwards more slowly than the ensuing sea-level rise, and remnants of these groundwater bodies are still found offshore (Cronin, 2012;Harrar et al, 2001;Person et al, 2003;Post et al, 2013).…”

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confidence: 99%

Electrical Resistivity Anomalies Offshore a Carbonate Coastline: Evidence for Freshened Groundwater?

Haroon

Micallef

Jegen

et al. 2021

Geophysical Research Letters

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Carbonate lithologies host considerable quantities of the Earth's freshwater resources and partially supply a quarter of the global population with drinkable water. Carbonates constitute substantial amounts of the global coastlines, yet it is not known if and how they can sustain freshened groundwater offshore. Here, we use controlled source electromagnetic, seismic reflection, and core sample data to derive a lithological model for the eastern margin of the Maltese Islands and identify four distinct resistivity anomalies within the Upper Coralline Limestone, Globigerina Limestone, and Blue Clay formations. The anomalies hosted in the former are likely associated to low porosities, whereas the anomaly within the latter is indicative of pore fluid freshening. Hydrogeological modeling suggests that freshened pore fluids, emplaced during sea-level lowstands and preserved in low permeability units, are potentially still found within carbonate shelves. However, resource potential is low due to its relict nature and low permeability host environment.

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confidence: 99%

Electrical Resistivity Anomalies Offshore a Carbonate Coastline: Evidence for Freshened Groundwater?

Haroon

Micallef

Jegen

et al. 2021

Geophysical Research Letters

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“…The rising demand for potable water in coastal regions has promoted growing research interest in detecting offshore freshened groundwater (OFG) worldwide (Post et al, 2013). OFG emplacement is commonly explained through either meteoric recharge during sea-level low-stands (e.g., Cohen et al, 2010;Meisler et al, 1984;Person et al, 2003) and/or through active meteoric recharge via permeable connections between onshore and offshore aquifers (e.g., Hong et al, 2019;Johnston, 1983;Weymer et al, 2022). Due to the ongoing pressure on terrestrial aquifers caused by environmental and anthropogenic stressors, offshore groundwater research has gained new urgency.…”

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confidence: 99%

Characterizing Offshore Freshened Groundwater Salinity Patterns Using Trans‐Dimensional Bayesian Inversion of Controlled Source Electromagnetic Data: A Case Study From the Canterbury Bight, New Zealand

Faghih,

Haroon,

Jegen

et al. 2024

Water Resources Research

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The study of offshore freshened groundwater (OFG) is gaining importance due to population growth and environmental pressure on coastal water resources. Marine controlled source electromagnetic (CSEM) methods can effectively map the spatial extent of OFG systems using electrical resistivity as a proxy. Integrating these resistivity models with sub‐surface properties, such as host‐rock porosity, allows for estimates of pore‐water salinity. However, evaluating the uncertainty in pore‐water salinity using resistivity models obtained from deterministic inversion approaches presents challenges, as they provide only one best‐fit model, with no associated estimate of uncertainty. To address this limitation, we employ trans‐dimensional Markov‐Chain Monte‐Carlo inversion on marine time‐domain CSEM data, acquired in the Canterbury Bight, New Zealand. We integrate resistivity posterior probability distributions with borehole and seismic reflection data to estimate pore‐water salinity with corresponding uncertainty estimates. The results highlight a low‐salinity groundwater body in the center of the survey area, hosted by consecutive silty‐ and fine‐sand layers approximately 20–60 km from the coast. The posterior probability distribution of resistivity models indicates freshening of the OFG body toward the shoreline within a permeable, coarse‐sand layer 40–150 m beneath the seafloor, suggesting an active connection between the OFG body and the terrestrial groundwater system. The approach demonstrates how Bayesian inversion constrains the uncertainties in resistivity models and subsequently in pore‐water salinity estimates. Our findings highlight the potential of Bayesian inversion to enhance our understanding of OFG systems and provide uncertainty constraints for hydrogeological modeling, thereby contributing to sustainable water resource development.

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Offshore Freshened Groundwater in Continental Shelf Environments

Person,

Micallef

2022

Unconventional Water Resources

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The effect of eustatic sea-level changes on saltwater-freshwater relations in the northern Atlantic Coastal Plain

Cited by 16 publications

References 9 publications

Electrical Resistivity Anomalies Offshore a Carbonate Coastline: Evidence for Freshened Groundwater?

Electrical Resistivity Anomalies Offshore a Carbonate Coastline: Evidence for Freshened Groundwater?

Characterizing Offshore Freshened Groundwater Salinity Patterns Using Trans‐Dimensional Bayesian Inversion of Controlled Source Electromagnetic Data: A Case Study From the Canterbury Bight, New Zealand

Offshore Freshened Groundwater in Continental Shelf Environments

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