An automated dye‐dilution based seepage meter for the time‐series measurement of submarine groundwater discharge

Sholkovitz, Edward R.; Herbold, Craig W.; Charette, Matthew A.

doi:10.4319/lom.2003.1.16

Cited by 59 publications

(29 citation statements)

References 37 publications

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“…The uncorrected (underestimated) flow measurements from 12.0 to 12.3 days present a conservative lower limit of the flow rate. Importantly, discharge from the spring did not cease at any time throughout the tidal cycle; that is, no flow reversal as often observed occurred [e.g., Chanton et al , 2003; Sholkovitz et al , 2003]. Correspondingly the hydraulic head difference remained positive, i.e., above tidal water level at all times (Figure 4b).…”

Section: Resultsmentioning

confidence: 73%

Geological controls and tidal forcing of submarine groundwater discharge from a confined aquifer in a coastal sand dune system

2007

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[1] Submarine groundwater discharge (SGD) into the ocean is increasingly recognized as an important component of land-ocean interaction. Numerous geological settings may be the source of terrestrially derived SGD, including spatially extensive sand dune systems, which are a common coastal setting in tropical, subtropical, and temperate regions throughout the world. Within the catchment of the Great Barrier Reef lagoon, numerous large-scale sand dune systems exist. Creeks and rivers draining these systems are largely absent; however, terrestrially derived groundwater discharges from discrete springs in the intertidal zone. The geological and hydrological controls of the discharge were investigated, using a combination of geological, geophysical, and hydrological methods. From sedimentary and geoelectric data it is inferred that a unit of sandy clay provides a confinement of the shallow aquifer system in the dune complex, with groundwater discharging where this layer is breached. Groundwater discharge flux was inversely correlated with tidal water level, but remained positive throughout the tidal cycle. A simple hydrological model indicates that the continuous discharge is the result of a change in hydraulic pressure of the confined aquifer in response to tidal forcing at the seaward limit of the aquitard, which is a previously undescribed effect of tidal modulation of SGD. The observed groundwater discharge is likely to have a significant effect on the biogeochemistry of the coastal environment, particularly in the absence of surface water drainage.Citation: Holliday, D., T. C. Stieglitz, P. V. Ridd, and W. W. Read (2007), Geological controls and tidal forcing of submarine groundwater discharge from a confined aquifer in a coastal sand dune system,

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Section: Resultsmentioning

confidence: 73%

Geological controls and tidal forcing of submarine groundwater discharge from a confined aquifer in a coastal sand dune system

2007

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“…Field and numerical studies quantified the tidal effect on SGD and showed that tide-induced recirculation can represent a major portion of total SGD [e.g., Li et al, 1999;Taniguchi, 2002;Robinson et al, 2007c;Li et al, 2009]. Seawater infiltration into an aquifer occurs on the rising tide and exfiltration (saline SGD) on the ebbing tide [Robinson et al, 1998;Sholkovitz et al, 2003;Robinson et al, 2007c]. As a nearshore aquifer is able to fill faster than it can drain, infiltration is greatest from the mid-tide to high tide mark and exfiltration is greatest towards the low tide mark [Robinson et al, 2007b].…”

Section: Tidesmentioning

confidence: 99%

Groundwater dynamics in subterranean estuaries of coastal unconfined aquifers: Controls on submarine groundwater discharge and chemical inputs to the ocean

Robinson¹,

Xin²,

Santos³

et al. 2018

Advances in Water Resources

198

138

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Sustainable coastal resource management requires sound understanding of interactions between coastal unconfined aquifers and the ocean as these interactions influence the flux of chemicals to the coastal ocean and the availability of fresh groundwater resources. The importance of submarine groundwater discharge in delivering chemical fluxes to the coastal ocean and the critical role of the subterranean estuary (STE) in regulating these fluxes is well recognized. STEs are complex and dynamic systems exposed to various physical, hydrological, geological, and chemical conditions that act on disparate spatial and temporal scales. This paper provides a review of the effect of factors that influence flow and salt transport in STEs, evaluates current understanding on the interactions between these influences, and synthesizes understanding of drivers of nutrient, carbon, greenhouse gas, metal and organic contaminant fluxes to the ocean.Based on this review, key research needs are identified. While the effects of density and tides are well understood, episodic and longer-period forces as well as the interactions between multiple influences remain poorly understood. Many studies continue to focus on idealized nearshore aquifer systems and future work needs to consider real world complexities such as geological heterogeneities, and non-uniform and evolving alongshore and cross-shore morphology. There is also a significant need for multidisciplinary research to unravel the interactions between physical and biogeochemical processes in the STE, as most existing studies treat these processes in isolation. Better understanding of this complex and dynamic system can improve sustainable management of coastal water resources under the influence of anthropogenic pressures and climate change.

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“…Moving away from the pier, seepage rates of 25 cm d −1 with peak flow of 37 cm d −1 were recorded at 2 m distance. At 3 m and 4 m distance from the pier, the seepage rates were further reduced to 6 cm d −1 (peak 12 cm d −1 ) and 2 cm d −1 (peak 6 cm d −1 ) respectively [ Sholkovitz et al , 2003] (Figure 3 and Table 1).…”

Section: Resultsmentioning

confidence: 99%

Estimation of submarine groundwater discharge from bulk ground electrical conductivity measurements

Rapaglia¹,

Bokuniewicz²

2008

J. Geophys. Res.

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The utility of bulk ground conductivity (BGC) measurements in the estimation of submarine groundwater discharge (SGD) was investigated at four sites covering a range of hydrogeological settings, namely Cockburn Sound (Australia); Shelter Island (USA); Ubatuba Bay (Brazil) and Flic‐en‐Flac Bay (Mauritius). At each of the sites, BGC was surveyed in the intertidal zone, and seepage meters were used for direct measurements of SGD flow rates. In the presence of detectable salinity gradients in the sediment, a negative correlation between SGD and BGC was recorded. The correlation is site‐specific and is dependent on both the type of sediment and the mixing processes. For example, at Shelter Island the maximum mean flow rates were 65 cm d−1 at a BGC of ∼0 mS cm−1 while at Mauritius maximum mean flow rates were 364 cm d−1 at a BGC of ∼0 mS cm−1. BGC measurements are used to estimate SGD over a large scale, and to separate its fresh and saline components. Extrapolating BGC measurements throughout the study sites yields a total discharge of 2.91, 1.59, 7.16, and 25.4 103 m3 d−1 km−1 of shoreline with a freshwater fraction of 41, 24, 29, and 63% at Cockburn Sound, Shelter Island, Ubatuba Bay, and Flic‐en‐Flac Bay respectively. The results demonstrate that ground conductivity is a useful tracer to survey and separate freshwater and recirculated seawater component of SGD. The presented investigation is a subset within a series of experiments designed to compare different methods to investigate SGD co‐organized and carried out by SCOR, LOICZ, IOC and IAEA.

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An automated dye‐dilution based seepage meter for the time‐series measurement of submarine groundwater discharge

Cited by 59 publications

References 37 publications

Geological controls and tidal forcing of submarine groundwater discharge from a confined aquifer in a coastal sand dune system

Geological controls and tidal forcing of submarine groundwater discharge from a confined aquifer in a coastal sand dune system

Groundwater dynamics in subterranean estuaries of coastal unconfined aquifers: Controls on submarine groundwater discharge and chemical inputs to the ocean

Estimation of submarine groundwater discharge from bulk ground electrical conductivity measurements

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