The Magnitude and Origin of Groundwater Discharge to Eastern U.S. and Gulf of Mexico Coastal Waters

Befus, K. M.; Kroeger, Kevin D.; Smith, Christopher G.; Swarzenski, Peter W.

doi:10.1002/2017gl075238

Cited by 36 publications

(38 citation statements)

References 67 publications

(92 reference statements)

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“…Surface water bodies are less present at volcanic and limestone catchments, hence, the results of CoCa‐RFSGD and the global models were closer. This can also be seen in the model results of Befus et al (). They concluded that small catchments of their numerical model approach discharged nearly all recharge as FSGD, while the majority of catchments were larger and discharged more than 50% of recharge to the ocean.…”

Section: Discussionsupporting

confidence: 74%

“…Quantification of transient terrestrial groundwater fluxes into the ocean is important because shallow groundwater is an easily accessible freshwater source for the growing coastal population (Moosdorf & Oehler, 2017) that is vulnerable to anthropogenic contaminants (McCoy & Corbett, 2009). However, transient Fresh Submarine Groundwater Discharge (FSGD) is difficult to measure and regional models that quantify FSGD are only available for the Unite States (Befus et al, 2017;Sawyer et al, 2016) and Sweden (Destouni et al, 2008), which are well-monitored regions. Scientific field and modeling studies on FSGD at ungauged basins with sparse hydrogeological data availability are underrepresented, although the potential relevance of these regions has been pointed out in the past (Beusen et al, 2013;Destouni et al, 2008;Dürr et al, 2008;Seitzinger et al, 2005;Zhou et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…Regional models are either water balance models with lumped parameters (Destouni et al, 2008;Sawyer et al, 2016) or discrete numerical groundwater models with high-resolution input data (Befus et al, 2017). Zhou et al (2018) compared these two different model approaches: A lumped water balance model based on the model of Sawyer et al (2016) and a distributed numerical groundwater flow model based on the model of Befus et al (2017). Both models are steady state models, which do not take seasonal changes into account.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Quantifying Regional Fresh Submarine Groundwater Discharge With the Lumped Modeling Approach CoCa‐RFSGD

Hajati

Sutanudjaja

Moosdorf

2019

Water Resources Research

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Fresh Submarine Groundwater Discharge (FSGD) has been increasingly recognized as a fresh water resource and potential path for pollutants to the ocean. Since directly measuring FSGD requires great effort and is currently only feasible at local scale, we developed the regional transient water balance model Coastal Catchment Regional FSGD (CoCa‐RFSGD) to calculate daily FSGD at long stretches of coastlines. The conceptualization of the model takes into account the main processes between soil and aquifer, and, depending on the research question, in situ data, as well as anthropogenic processes, can be added to the water balance. It provides daily FSGD per coastal catchment. Within this model, FSGD is the precipitation surplus of the catchment area minus surface runoff, which highly correlates with the top soil water‐holding capacity and less with soil hydraulic conductivities. The model uses the island of Java, Indonesia, as an example. Java generates a total FSGD of 15.27 km3/a. Extrapolating the identified correlation of top soil water‐holding capacity and precipitation surplus on FSGD to the world highlights Indonesia, Vietnam, Nigeria, Cameroon, Equatorial Guinea, and Columbia as potential FSGD hot spots. Using mean global aquifer hydraulic conductivities might underestimate the seasonal variation of FSGD on Java. The model can be applied anywhere in the world to locate regional FSGD hot spots without obtaining in situ data, because it can run solely with global data sets. Hence, it is especially feasible for the locations mentioned. Furthermore, FSGD studies can be supplemented with this model by upscaling point measurements of FSGD to a full year.

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Section: Discussionsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Quantifying Regional Fresh Submarine Groundwater Discharge With the Lumped Modeling Approach CoCa‐RFSGD

Hajati

Sutanudjaja

Moosdorf

2019

Water Resources Research

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“…The combined error associated with our assumptions is difficult to quantify for the near‐global coast. However, in a comparison of 10 sites from the continental United States (Bokuniewicz, ; Bokuniewicz et al, ; Hays & Ullman, ; Mulligan & Charette, ; Reay et al, ; Russoniello et al, ; Santos et al, ; Simmons, ; Uddameri et al, ; Zimmermann et al, ), our water budget analysis yields similar estimates of fresh SGD as seepage meter studies (Sawyer et al, ), other water budget calculations, and validated three‐dimensional groundwater flow models (Befus et al, ; Zhou et al, ; supporting information Figure S1). Our estimates tend to be lower than field‐based estimates, likely because of our conservative approach for delineating coastal recharge areas, which would tend to exclude groundwater imports from upland basins.…”

Section: Methodssupporting

confidence: 67%

Fresh Submarine Groundwater Discharge to the Near‐Global Coast

Zhou

Sawyer

David

et al. 2019

Geophysical Research Letters

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The flow of fresh groundwater to the ocean through the coast (fresh submarine groundwater discharge or fresh SGD) plays an important role in global biogeochemical cycles and coastal water quality. In addition to delivering dissolved elements from land to sea, fresh SGD forms a natural barrier against salinization of coastal aquifers. Here we estimate groundwater discharge rates through the near‐global coast (60°N to 60°S) at high resolution using a water budget approach. We find that tropical coasts export more than 56% of all fresh SGD, while midlatitude arid regions export only 10%. Fresh SGD rates from tectonically active margins (coastlines along tectonic plate boundaries) are also significantly greater than passive margins, where most field studies have been focused. Active margins combine rapid uplift and weathering with high rates of fresh SGD and may therefore host exceptionally large groundwater‐borne solute fluxes to the coast.

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“…In this alternative, the terrestrially sourced fluid re‐emerges as low‐salinity springs from outcrops seaward of the coastline (Faure et al, ; Orange et al, ; Post et al, ; Puig et al, ). Fresh groundwater discharge into nearshore seawater environments has been shown previously to contribute to the physical and chemical environment of some restricted coastal waters, but the role of coastal groundwater at the larger regional to continental scales remains poorly defined (Befus et al, ; Michael et al, ).…”

Section: Models For Emission Site Depthsmentioning

confidence: 99%

Anomalous Concentration of Methane Emissions at the Continental Shelf Edge of the Northern Cascadia Margin

et al. 2019

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A recent compilation of methane plumes detected offshore Washington State includes 1,772 individual bubble streams issuing from 491 discrete vent sites. The majority of these plume sites form a narrow 10‐km‐wide band located shallower than 250‐m water depth, with most sites located near the 175‐m‐deep continental shelf break that tracks the head scarps of large submarine canyons. Archive multichannel seismic profiles over the Cascadia shelf and uppermost margin that were co‐located within a few hundred meters with active emission sites show that methane bubble streams arise from listric/normal faults and triangular‐shaped regions of disturbed seismic reflectors that intersect the seafloor and extend several kilometers into the subsurface. Geological processes were evaluated for producing the narrow emission site depths including nonuniform distribution of methane within the Cascadia accretionary sediment wedge and horizontal transfer of groundwater from onshore subaerial sources. A model of enhanced sediment permeability arising from a contrasting response between the inner and outer portions of the accretionary wedge deformation during a megathrust earthquake cycle appears the most likely mechanism. This faulting is generated during extension of the overriding plate during megathrust earthquake cycles, with semicontinuous permeability enhancement of the fluid pathways from excitation by contemporary incident seismic waves.

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The Magnitude and Origin of Groundwater Discharge to Eastern U.S. and Gulf of Mexico Coastal Waters

Cited by 36 publications

References 67 publications

Quantifying Regional Fresh Submarine Groundwater Discharge With the Lumped Modeling Approach CoCa‐RFSGD

Quantifying Regional Fresh Submarine Groundwater Discharge With the Lumped Modeling Approach CoCa‐RFSGD

Fresh Submarine Groundwater Discharge to the Near‐Global Coast

Anomalous Concentration of Methane Emissions at the Continental Shelf Edge of the Northern Cascadia Margin

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