Watertable Overheight Due to Wave Runup on a Sandy Beach

Kang, Hong-Yoon; Nielsen, Peter; Hanslow, David J.

doi:10.1061/9780784400890.154

Cited by 17 publications

(20 citation statements)

References 2 publications

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“…This circulation extends to depths comparable with the width of the surf zone, typically of the order of 10 1 -10 2 m [27]. In addition, Kang et al [21] showed that wave run-up forces infiltration into drained sediments predominantly on the rising tide.…”

Section: Introductionmentioning

confidence: 97%

Effect of tidal forcing on a subterranean estuary

Robinson

Barry

2007

Advances in Water Resources

402

375

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Section: Introductionmentioning

confidence: 97%

Effect of tidal forcing on a subterranean estuary

Robinson

Barry

2007

Advances in Water Resources

402

375

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“…On the basis of the available wave data [3,6,8,9,12], it is not possible to say which form is the most accurate in general. (There is not enough detailed aquifer information).…”

Section: Watertable Wavesmentioning

confidence: 99%

“…However, because there is a phase shift between h tot and h, n d de®ned by Eq. (6), is a complex number.…”

Section: Introductionmentioning

confidence: 99%

Watertable dynamics under capillary fringes: experiments and modelling

Nielsen

Perrochet

2000

Advances in Water Resources

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100

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Watertable heights and total moisture content were measured in a sand column where the piezometric head at the base (``the driving head'') varied as a simple harmonic with periods in the range from 14.5 min to 6.5 h. The watertable height ht responded very closely to the driving head compared with the predictions of previous analytical and numerical models. The total moisture quanti®ed as an equivalent, saturated height h tot t varied very little compared with the watertable height. Neither ht nor h tot t deviated signi®cantly from simple harmonics when the driving head was simple harmonic. This indicates that non-linear eects are weak and hence that analysis based on linear solutions have fairly broad applicability. When ht and h tot t are simple harmonic, the ratio n d dh tot adtadhadt is a constant in the complex formalism. Its magnitude jn d j is the usual eective porosity while its argument accounts for the phase shift which is always observed between ht and h tot t. Within the current range of experiments this dynamic, eective porosity n d appears to be almost independent of the forcing frequency, i.e., it is a function of the soil and its compaction only. Introducing the complex n d enables analytical solution for the watertable height in the column which is simpler and more consistently accurate over a range of frequencies than previous models including RichardÕs equation with van Genuchten parameters corresponding to the measured water retention curve. The complex n d can be immediately adopted into linear watertable problems in 1 or 2 horizontal dimensions. Compared with``with``no fringe solutions'', this leads to modi®cation of the watertable behaviour which is in agreement with experiments and previous models. The use of a complex n d to account for the capillary fringe in watertable models has the advantage, compared with previous models, e.g., [Parlange J-Y, Brutsaert W. A capillary correction for free surface ¯ow of groundwater. Water Resour Res 1987; 23(5):805±8.] that the order of the dierential equations is lower. For example, the linearised Boussinesq equation with complex n d is still of second order while the Parlange and Brutsaert equation is of third order. The extra work of calculating the imaginary part of the initially complex solution is insigni®cant compared to dealing with higher order equations. On the basis of the presently available data it also seems that thè`complex n d approach'' is more accurate. This is to be expected since the complex n d accounts implicitly for hysteresis while the Green±Ampt model does not. With respect to linear watertable waves, accounting for the capillary fringe through the complex n d is a very simple extension since the determination of wave numbers already involves complex numbers.

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“…[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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Watertable Overheight Due to Wave Runup on a Sandy Beach

Cited by 17 publications

References 2 publications

Effect of tidal forcing on a subterranean estuary

Effect of tidal forcing on a subterranean estuary

Watertable dynamics under capillary fringes: experiments and modelling

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

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