Open AccessMeasurements and modeling of swash‐induced pressure gradients in the surface layers of a sand beach
Author(s) -
Baldock Tom E.,
Baird Andrew J.,
Horn Diane P.,
Mason Travis
Publication year - 2001
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1999jc000170
Subject(s) - swash , geology , diffusion , shore , flow (mathematics) , sediment transport , sediment , pressure gradient , groundwater flow , geomorphology , pore water pressure , mechanics , geotechnical engineering , groundwater , aquifer , oceanography , physics , thermodynamics
Field measurements of swash‐induced hydraulic (pressure) gradients in the surface layers of a sand beach are presented and compared to a one‐dimensional diffusion model. The model provides a description of flow through a porous, quasi‐saturated sediment and is driven by the time‐varying swash depth on the beach surface. The field measurements broadly show four different types of pressure propagation behavior, which appear dependent on cross‐shore position in the swash zone. The hydraulic gradients within the surface layers of the beach are typically found to be much greater than those likely to be generated by tidally‐induced groundwater flow. In these instances the diffusion model generally provides a good description of the data. However, very large hydraulic gradients are frequently observed just below the beach surface, and these cannot be adequately described by the diffusion model. A mechanism is proposed through which these large hydraulic gradients could be generated.