Surface-groundwater flow numerical model for barrier beach with exfiltration incorporated bottom boundary layer model

Perera, Eranda; Zhu, Fangfang; Dodd, Nicholas; Briganti, Riccardo; Blenkinsopp, Chris; Turner, Ian L

Abstract

A surface-groundwater flow model is developed for the swash flow on a barrier beach. The non-linear shallow water equations are used to simulate the surface flow. Laplace's equation is used to describe the groundwater flow and is solved using the Boundary Integral Equation Method to provide potential heads and normal potential derivatives at and within the boundaries of the barrier. An exfiltration incorporated bottom boundary layer sub-model is used to obtain bed shear stress. The groundwater model is verified against the numerical test results in Kazemzadeh-Parsi and Danesh-mand (2012) for the groundwater flow through a rectangular dam. The coupled surface-groundwater model is validated against the prototype-scale BARDEX II experimental results (Turner et al., 2016). The steady-state groundwater flow comparisons show excellent agreement in phreatic surfaces. The comparisons of groundwater flow under the action of waves show reasonably good agreement with experimental results in phreatic surfaces. The simulated time averaged pore velocities for the runs with and without waves are in satisfactory agreement with experimental results in general, and certain discrepancies are observed near the beach side. The bed shear stress variation due to exfiltration is investigated by incorporating the modified logarithmic bottom boundary layer model of Cheng and Chiew (1998) in the coupled surface-groundwater flow model. The results confirm that as exfil-tration increases, bed shear stress decreases as a result of thickening of the bottom boundary layer. Highlights • A coupled surface-groundwater flow numerical model is developed and validated against the BARDEX II experimental results. • Seepage under a moving bore shows alternate exfiltration and infiltration before and after the bore front respectively.

Citation

Perera, E., Zhu, F., Dodd, N., Briganti, R., Blenkinsopp, C., & Turner, I. L. (2019). Surface-groundwater flow numerical model for barrier beach with exfiltration incorporated bottom boundary layer model. Coastal Engineering Journal, 146, 47-64. https://doi.org/10.1016/j.coastaleng.2018.12.002

• Journal Article Type: Article
• Acceptance Date: Dec 2, 2018
• Online Publication Date: Dec 5, 2018
• Publication Date: 2019-04
• Deposit Date: Dec 12, 2018
• Publicly Available Date: Dec 6, 2019
• Journal: Coastal Engineering
• Print ISSN: 0578-5634
• Electronic ISSN: 1793-6292
• Publisher: World Scientific
• Peer Reviewed: Peer Reviewed
• Volume: 146
• Pages: 47-64
• DOI: https://doi.org/10.1016/j.coastaleng.2018.12.002
• Keywords: Environmental Engineering; Ocean Engineering
• Public URL: https://nottingham-repository.worktribe.com/output/1409623
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0378383918301443
• Additional Information: This article is maintained by: Elsevier; Article Title: Surface-groundwater flow numerical model for barrier beach with exfiltration incorporated bottom boundary layer model; Journal Title: Coastal Engineering; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.coastaleng.2018.12.002; Content Type: article; Copyright: © 2018 Elsevier B.V. All rights reserved.
• Contract Date: Dec 12, 2018