A Richards’ equation-based model for wave-resolving simulation of variably-saturated beach groundwater flow dynamics

This study introduces a model based on Richards’ equation to describe variably-saturated beach groundwater flow. The surface wave propagation is computed by the phase-resolving non-hydrostatic SWASH code. The SWASH data are used to make a suitable dynamic boundary condition at the beach face to forc...

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Bibliographic Details
Published in:Journal of hydrology (Amsterdam) 2023-04, Vol.619, p.129344, Article 129344
Main Authors: Clément, Jean-Baptiste, Sous, Damien, Bouchette, Frédéric, Golay, Frédéric, Ersoy, Mehmet
Format: Article
Language:English
Subjects:
Adaptive discontinuous Galerkin method
Barrier beach
Earth Sciences
Engineering Sciences
Fluids mechanics
Hydrology
Mechanics
Numerical modelling
Oceanography
Sciences of the Universe
Seepage
Swash zone
Unsaturated porous media
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Summary:This study introduces a model based on Richards’ equation to describe variably-saturated beach groundwater flow. The surface wave propagation is computed by the phase-resolving non-hydrostatic SWASH code. The SWASH data are used to make a suitable dynamic boundary condition at the beach face to force Richards’ equation. The latter is solved by a weighted discontinuous Galerkin method together with adaptive mesh refinement. The model is validated by comparison with a laboratory experiment of a transient water table recharge problem. Then, the BARDEX II prototype-scale experiment is considered to assess the model abilities for beach groundwater dynamics. The barrier beach is studied for three cases with different lagoon levels. Steady-state results with no-wave conditions show excellent agreement. Transient waves simulations are evaluated in terms of pressure heads, saturations, water table position and groundwater velocities for time-averaged, swash-resolving and spectral analysis. Results bring interesting insights about beach groundwater modelling by comparison with the experimental data as well as a Darcy’s equation-based model. A first investigation is carried out to assess the groundwater effect on the bed sediment dynamics through the modification of sediment relative weight. •A Richards-based model for wave-driven variably-saturated beach groundwater dynamics.•Model validation against BARDEX II large-scale sand barrier experiments.•Detailed 2DV analysis of swash-driven groundwater flow dynamics.
ISSN:0022-1694
1879-2707
DOI:10.1016/j.jhydrol.2023.129344