Response of the salt–freshwater interface in a coastal aquifer to a wave-induced groundwater pulse: field observations and modelling

Cartwright, Nick; Li, Ling; Nielsen, Peter

doi:10.1016/j.advwatres.2003.12.005

Cited by 72 publications

(51 citation statements)

References 8 publications

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“…Comprehensive SI measurement campaigns integrated with modeling efforts that adopt formal calibration and predictive uncertainty analyses are a key area for future research in SI 64 characterization. We found limited cases where water level, hydrochemistry, environmental tracer and geophysical information have been intensively collected and compared with geological controls and hydrological stresses in a quantitative framework.…”

Section: Measurement and Modelingmentioning

confidence: 99%

Seawater intrusion processes, investigation and management: Recent advances and future challenges

Werner

Bakker

Post

et al. 2013

Advances in Water Resources

1,205

666

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Section: Measurement and Modelingmentioning

confidence: 99%

Seawater intrusion processes, investigation and management: Recent advances and future challenges

Werner

Bakker

Post

et al. 2013

Advances in Water Resources

1,205

666

View full text Add to dashboard Cite

“…[4] Most previous investigations into the coupling of the ocean with coastal aquifers have been based on tidally induced water table fluctuations [e.g., Lanyon et al, 1982;Nielsen, 1990;Baird and Horn, 1996;Li et al, 1997a;Baird et al, 1998;Raubenheimer et al, 1999] although field observations from exposed coasts have shown that wave forcing is at least as important [e.g., Kang et al, 1994;Nielsen, 1999;Cartwright et al, 2004a]. Until recently, the coupling of the swash zone with the porous beach matrix had received relatively little attention.…”

Section: Introductionmentioning

confidence: 99%

Swash‐aquifer interaction in the vicinity of the water table exit point on a sandy beach

et al. 2006

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[1] The coupling of sandy beach aquifers with the swash zone in the vicinity of the water table exit point is investigated through simultaneous measurements of the instantaneous shoreline (swash front) location, pore pressures and the water table exit point. The field observations reveal new insights into swash-aquifer coupling not previously gleaned from measurements of pore pressure only. In particular, for the case where the exit point is seaward of the observation point, the pore pressure response is correlated with the distance between the exit point and the shoreline in that when the distance is large the rate of pressure drop is fast and when the distance is small the rate decreases. The observations expose limitations in a simple model describing exit point dynamics which is based only on the force balance on a particle of water at the sand surface and neglects subsurface pressures. A new modified form of the model is shown to significantly improve the model-data comparison through a parameterization of the effects of capillarity into the aquifer storage coefficient. The model enables sufficiently accurate predictions of the exit point to determine when the swash uprush propagates over a saturated or a partially saturated sand surface, potentially an important factor in the morphological evolution of the beach face. Observations of the shoreward propagation of the swash-induced pore pressure waves ahead of the runup limit shows that the magnitude of the pressure fluctuation decays exponentially and that there is a linear increase in time lags, behavior similar to that of tidally induced water table waves. The location of the exit point and the intermittency of wave runup events is also shown to be significant in terms of the shore-normal energy distribution. Seaward of the mean exit point location, peak energies are small because of the saturated sand surface within the seepage face acting as a ''rigid lid'' and limiting pressure fluctuations. Landward of the mean exit point the peak energies grow before decreasing landward of the maximum shoreline position.

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“…The higher amplitude and lower frequency enhance each other's effect on increasing the mixing zone. Cartwright et al (2004) investigated much smaller spatial (horizontal and vertical) and temporal scales than Underwood et al (1992) and Kiro et al (2008), and neglected thickness variability of the mixing zone.…”

Section: S Eeman Et Al: Response To Recharge Variation Of Thin Rainmentioning

confidence: 99%

“…In agreement with Kiro et al, Andersen et al (1988) saw that small but long-term changes in groundwater level in a drinking water well area can significantly influence the position of the mixing zone, whereas annual variability did not have any influence. Cartwright et al (2004) investigated the response of the mixing zone to tides and waves on a beach.…”

Section: S Eeman Et Al: Response To Recharge Variation Of Thin Rainmentioning

confidence: 99%

Response to recharge variation of thin rainwater lenses and their mixing zone with underlying saline groundwater

Eeman

Zee

Leijnse

et al. 2012

Hydrol. Earth Syst. Sci.

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Abstract. In coastal zones with saline groundwater, fresh groundwater lenses may form due to infiltration of rain water. The thickness of both the lens and the mixing zone, determines fresh water availability for plant growth. Due to recharge variation, the thickness of the lens and the mixing zone are not constant, which may adversely affect agricultural and natural vegetation if saline water reaches the root zone during the growing season. In this paper, we study the response of thin lenses and their mixing zone to variation of recharge. The recharge is varied using sinusoids with a range of amplitudes and frequencies. We vary lens characteristics by varying the Rayleigh number and Mass flux ratio of saline and fresh water, as these dominantly influence the thickness of thin lenses and their mixing zone. Numerical results show a linear relation between the normalised lens volume and the main lens and recharge characteristics, enabling an empirical approximation of the variation of lens thickness. Increase of the recharge amplitude causes increase and the increase of recharge frequency causes a decrease in the variation of lens thickness. The average lens thickness is not significantly influenced by these variations in recharge, contrary to the mixing zone thickness. The mixing zone thickness is compared to that of a Fickian mixing regime. A simple relation between the travelled distance of the centre of the mixing zone position due to variations in recharge and the mixing zone thickness is shown to be valid for both a sinusoidal recharge variation and actual records of daily recharge data. Starting from a step response function, convolution can be used to determine the effect of variable recharge in time. For a sinusoidal curve, we can determine delay of lens movement compared to the recharge curve as well as the lens amplitude, derived from the convolution integral. Together the proposed equations provide us with a first order approximation of lens characteristics using basic lens and recharge parameters without the use of numerical models. This enables the assessment of the vulnerability of any thin fresh water lens on saline, upward seeping groundwater to salinity stress in the root zone.

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Response of the salt–freshwater interface in a coastal aquifer to a wave-induced groundwater pulse: field observations and modelling

Cited by 72 publications

References 8 publications

Seawater intrusion processes, investigation and management: Recent advances and future challenges

Seawater intrusion processes, investigation and management: Recent advances and future challenges

Swash‐aquifer interaction in the vicinity of the water table exit point on a sandy beach

Response to recharge variation of thin rainwater lenses and their mixing zone with underlying saline groundwater

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