Measurements and modelling of beach groundwater flow in the swash-zone: a review

Horn, Diane P.

doi:10.1016/j.csr.2006.02.001

Cited by 104 publications

(91 citation statements)

References 85 publications

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“…The second is the reverse Wieringermeer effect (RWE) dealing with the case where the capillary fringe extends from the water table almost to the ground surface leading to a limited or no storage capacity in the zone between water table and soil surface as well as a specific yield approaching zero value. In these conditions the pores within the capillary fringe are saturated and the addition of a very small amount of water relieves the tensions in the capillaries resulting in a rapid and high water table rise to the land surface (Gillham, 1984;Novakowski and Gillham, 1988;Horn, 2006). Overall, the groundwater fluctuation in Metouia Oasis shown in Figure 2 is more consistent with the reverse Wieringermeer effect.…”

Section: Shallow Groundwater Monitoring Systemsupporting

confidence: 73%

A high measurement frequency based assessment of shallow groundwater fluctuations in Metouia Oasis, South Tunisia

Ibrahimi

Miyazaki

Nishimura

2010

Hydrological Research Letters

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Abstract:The Metouia Oasis (South Tunisia) is increasingly being impacted by high soil salinity, leading to yield losses and ultimately to farmland abandon. In this area shallow groundwater rise is considered the major factor responsible for salt accumulation in soils. However, limited data exist on groundwater fluctuations in Metouia Oasis, despite the criticality of such information for accurate soil salinity assessment. In this study, groundwater behavior was monitored at a high measurement frequency. An observation well was installed and equipped with a water level sensor (Diver DI240, Van Essen Instrument) to record the groundwater fluctuation at 30 minute intervals. The results showed that at seasonal basis, groundwater was characterized by a declining phase during spring and summer seasons followed by a rising phase starting from mid-October. Further, the hydrograph was characterized by several rapid water table rises following recharge events followed by extended periods of water table decline. The hourly observations at daily basis displayed strong evidence of diurnal effects on groundwater patterns. The results from this study suggest that consideration should be given to monitoring water table behavior in Metouia Oasis more frequently in order to capture daily and seasonal patterns.

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Section: Shallow Groundwater Monitoring Systemsupporting

confidence: 73%

A high measurement frequency based assessment of shallow groundwater fluctuations in Metouia Oasis, South Tunisia

Ibrahimi

Miyazaki

Nishimura

2010

Hydrological Research Letters

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“…Another important effect related to the infiltration/exfiltration is the alteration of drag forces and potential for sediment mobility, as the effective weight of the upper elements of the bed are also modified. This effect has been addressed as the stabilization/destabilization of the bed [for reviews, see Baldock et al [2001] and Horn [2006]). In summary, the mechanisms that affect the BL have been identified but still, it is difficult to assess which of the aforementioned effects are dominant under varied conditions.…”

Section: Introductionmentioning

confidence: 99%

On the role of infiltration and exfiltration in swash zone boundary layer dynamics

et al. 2015

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Boundary layer dynamics are investigated using a 2‐D numerical model that solves the Volume‐Averaged Reynolds‐Averaged Navier‐Stokes equations, with a VOF‐tracking scheme and a k ‐ ϵ turbulence closure. The model is validated with highly resolved data of dam break driven swash flows over gravel impermeable and permeable beds. The spatial gradients of the velocity, bed shear stress, and turbulence intensity terms are investigated with reference to bottom boundary layer (BL) dynamics. Numerical results show that the mean vorticity responds to flow divergence/convergence at the surface that result from accelerating/decelerating portions of the flow, bed shear stress, and sinking/injection of turbulence due to infiltration/exfiltration. Hence, the zero up‐crossing of the vorticity is employed as a proxy of the BL thickness inside the shallow swash zone flows. During the uprush phase, the BL develops almost instantaneously with bore arrival and fluctuates below the surface due to flow instabilities and related horizontal straining. In contrast, during the backwash phase, the BL grows quasi‐linearly with less influence of surface‐induced forces. However, the infiltration produces a reduction of the maximum excursion and duration of the swash event. These effects have important implications for the BL development. The numerical results suggest that the BL growth rate deviates rapidly from a quasi‐linear trend if the infiltration is dominant during the initial backwash phase and the flat plate boundary layer theory may no longer be applicable under these conditions.

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“…The dynamics of this rapid infiltration-exfiltration have been studied with respect to its effect on beach sediment transport and coastal morphology [e.g., Turner and Nielsen, 1997;Horn et al, 1998;Masselink and Hughes, 1998;Turner and Masselink, 1998;Baldock et al, 2001;Elfrink and Baldock, 2002;Horn, 2006;Bakhtyar et al, 2012]. Heiss et al…”

Section: Wavesmentioning

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

228

148

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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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Measurements and modelling of beach groundwater flow in the swash-zone: a review

Cited by 104 publications

References 85 publications

A high measurement frequency based assessment of shallow groundwater fluctuations in Metouia Oasis, South Tunisia

A high measurement frequency based assessment of shallow groundwater fluctuations in Metouia Oasis, South Tunisia

On the role of infiltration and exfiltration in swash zone boundary layer dynamics

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

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