Water flow and solute transport due to Macrotide in a gravel beach

Abdollahi-Nasab, Ali; Geng, Xiaolong; Boufadel, Michel C.

doi:10.1016/j.jhydrol.2019.123935

Cited by 3 publications

(2 citation statements)

References 56 publications

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“…Forward particle tracking was performed among the cases to reveal the flow pathways and associated transit time within the groundwater circulation zone of the beach driven by tides. A particle tracking code, NEMO3D, based on the random walk particle tracking algorithm (Abdollahi‐Nasab et al, ; Geng, Boufadel, Ozgokmen, et al, ) was used for these simulations. The neutrally buoyant particles were released at 0.1 m interval along the beach face near upper intertidal zone, spanning from x = 1.0 to 2.5 m.…”

Section: Methodsmentioning

confidence: 99%

Numerical Study of Solute Transport in Heterogeneous Beach Aquifers Subjected to Tides

Geng

Boufadel

Rajaram

et al. 2020

Water Resources Research

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A numerical study, based on a variably saturated groundwater flow model within a Monto Carlo framework, was conducted to investigate flow and solute transport in a heterogeneous beach aquifer subjected to tides. The numerical simulations were conducted based on our previous tracer experiments performed in a laboratory beach. Heterogeneity is assumed to be multifractal generated using the Universal Multifractal model. Our results show that heterogeneity greatly alters temporal and spatial evolution of the tracer plume migrating in the beach. The spreading coefficient of the plume shows very dynamic response to tides; it increases as the tidally driven recirculation cell overlaps with the plume and decreases as the recirculation cell moves far from the plume with tides. Descriptive statistics suggests that heterogeneity enhances spreading of the plume in the beach in an ensemble sense along with significant spatial and temporal variation. Due to heterogeneity, high spots of the pore water velocity are formed within the recirculation cell, creating transient preferential flow paths in the beach in response to tides. Contours of the Okubo‐Weiss (OW) parameter show that coupling with tides, heterogeneity creates vorticity‐dominated flow regions and also expands strain‐dominated flow regions more downward, indicating complex local‐scale mixing in the beach, compared to corresponding homogeneous case. Geologic heterogeneity also alters the spatial extent of the recirculating cell and induces highly variable transit time along the recirculating flow paths. The results provide insights into effects of geologic heterogeneity on seawater‐groundwater mixing and associated solute transport processes in tidally influenced coastal aquifers.

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Section: Methodsmentioning

confidence: 99%

Numerical Study of Solute Transport in Heterogeneous Beach Aquifers Subjected to Tides

Geng

Boufadel

Rajaram

et al. 2020

Water Resources Research

Self Cite

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“…During high tide, the hydraulic head of the lower aquifer was at the same height as the sea water level, and the head dropped following the falling tide. During the low tide, the head remained constant at the MSL, suggesting the drainage slowed in the lower aquifer (Abdollahi‐Nasab et al, 2019).…”

Section: Resultsmentioning

confidence: 99%

Groundwater, salt and contaminant transport in a coastal aquifer system with a low‐permeability layer in the intertidal zone

Li,

Gibbes,

Liu

et al. 2024

Hydrological Processes

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Low‐permeability layer (LPL), formed by natural deposit or artificial reclamation and commonly found below the intertidal zone of coastal groundwater system, can retard the ingress of seawater and contaminants, and shorten the travel time of the land‐sourced contaminant to the marine environment compared with a homogenous sandy coastal aquifer. However, there is limited understanding on how an intertidal LPL, a condition occurred in a coastal aquifer at Moreton Bay, Australia, influences the groundwater and contaminant transport across the shallow beach aquifer system. We characterized the aquifer hydrological parameters, monitored the in situ groundwater heads, and constructed a 2‐D numerical model to analyses the cross‐shore hydrological processes in this stratified system. The calibrated model suggests that in the lower aquifer, the inland‐source fresh groundwater flowed horizontally towards the sea, upwelled along the freshwater–saltwater interface, and exited the aquifer at the shore below the LPL. Whereas in the upper aquifer, the tidally driven seawater circulation formed a barrier that prevented fresh groundwater from horizontal transport and discharge to the beach above the LPL, thereby directing its leakage to the lower aquifer. A contaminant represented by a conservative tracer was ‘released’ the upper aquifer in the model and results showed that the spreading extent of the contaminant plume, the maximum rate of contaminant discharge to the ocean, and its plume length decreased compared with a simulation case in a homogenous sandy aquifer. Sensitivity analysis was also conducted to investigate the characteristics of the LPL, including its continuity and hydraulic conductivity, which were found to vary along the beach at Moreton Bay. The result shows that with a lower hydraulic conductivity and continuous layer of LPL reduced the groundwater exchange and contaminant transport between upper and lower aquifer. The findings from the combined field and modelling investigations on the impact of an intertidal LPL on coastal aquifer systems highlight its significant implications to alter the groundwater and mass transport across the land–ocean interface.

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Driving Processes of Hydrodynamics and Hydrochemistry of Freshwater Lenses on a Naturally Controlled Coral Island: Animal and Plant Effects Cannot Be Ignored

Xiao,

Han,

Cao

et al. 2024

Preprint

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Water flow and solute transport due to Macrotide in a gravel beach

Cited by 3 publications

References 56 publications

Numerical Study of Solute Transport in Heterogeneous Beach Aquifers Subjected to Tides

Numerical Study of Solute Transport in Heterogeneous Beach Aquifers Subjected to Tides

Groundwater, salt and contaminant transport in a coastal aquifer system with a low‐permeability layer in the intertidal zone

Driving Processes of Hydrodynamics and Hydrochemistry of Freshwater Lenses on a Naturally Controlled Coral Island: Animal and Plant Effects Cannot Be Ignored

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