Modeling the Impact of the Implementation of a Submerged Structure on Surf Zone Sandbar Dynamics
Coastal defense strategies based on structures are increasingly unpopular as they are costly, leave lasting scars on the landscape, and sometimes have limited effectiveness or even adverse impacts. While a clear improvement concerning aesthetic considerations using soft submerged breakwater is unden...
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doaj-c9e25b82b35440cab4a62d7e3d3f79ed2021-04-02T15:28:50ZengMDPI AGJournal of Marine Science and Engineering2077-13122019-04-017411710.3390/jmse7040117jmse7040117Modeling the Impact of the Implementation of a Submerged Structure on Surf Zone Sandbar DynamicsClément Bouvier0Bruno Castelle1Yann Balouin2BRGM, Occitanie-Pyrénées-Méditerranée (SGR/LRO), 1039 Rue de Pinville, 34000 Montpellier, FranceCNRS, UMR EPOC, University Bordeaux, Allée Geoffroy Saint-Hilaire, CS 50023, 33615 Pessac, FranceBRGM, Occitanie-Pyrénées-Méditerranée (SGR/LRO), 1039 Rue de Pinville, 34000 Montpellier, FranceCoastal defense strategies based on structures are increasingly unpopular as they are costly, leave lasting scars on the landscape, and sometimes have limited effectiveness or even adverse impacts. While a clear improvement concerning aesthetic considerations using soft submerged breakwater is undeniable, their design has often focused on wave transmission processes across the crest of the structure, overlooking short- to medium-term morphodynamic responses. In this study, we used a time- and depth-averaged morphodynamic model to investigate the impact of the implementation of a submerged breakwater on surf zone sandbar dynamics at the beach of Sète, SE France. The hydrodynamic module was calibrated with data collected during a field experiment using three current profilers deployed to capture rip-cell circulation at the edge of the structure. The model showed good agreement with measurements, particularly for the longshore component of the flow (RMSE = 0.07 m/s). Results showed that alongshore differential wave breaking at the edge of the submerged breakwater drove an intense (0.4 m/s) two-dimensional circulation for low- to moderate-energy waves. Simulations indicated that inner-bar rip channel development, which was observed prior to the submerged reef implementation, was inhibited in the lee of the structure as rip-cell circulation across the inner bar disappeared owing to persistently low-energy breaking waves. The cross-shore sandbar dynamics in the lee of the structure were also impacted due to the drastic decrease of the offshore-directed flow over the inner-bar during energetic events. This paper highlights that implementation of a submerged breakwater results in larges changes in nearshore hydrodynamics that, in turn, can affect overall surf zone sandbar behavior.https://www.mdpi.com/2077-1312/7/4/117submerged breakwatermorphodynamic modelsandbar dynamics |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Clément Bouvier Bruno Castelle Yann Balouin |
spellingShingle |
Clément Bouvier Bruno Castelle Yann Balouin Modeling the Impact of the Implementation of a Submerged Structure on Surf Zone Sandbar Dynamics Journal of Marine Science and Engineering submerged breakwater morphodynamic model sandbar dynamics |
author_facet |
Clément Bouvier Bruno Castelle Yann Balouin |
author_sort |
Clément Bouvier |
title |
Modeling the Impact of the Implementation of a Submerged Structure on Surf Zone Sandbar Dynamics |
title_short |
Modeling the Impact of the Implementation of a Submerged Structure on Surf Zone Sandbar Dynamics |
title_full |
Modeling the Impact of the Implementation of a Submerged Structure on Surf Zone Sandbar Dynamics |
title_fullStr |
Modeling the Impact of the Implementation of a Submerged Structure on Surf Zone Sandbar Dynamics |
title_full_unstemmed |
Modeling the Impact of the Implementation of a Submerged Structure on Surf Zone Sandbar Dynamics |
title_sort |
modeling the impact of the implementation of a submerged structure on surf zone sandbar dynamics |
publisher |
MDPI AG |
series |
Journal of Marine Science and Engineering |
issn |
2077-1312 |
publishDate |
2019-04-01 |
description |
Coastal defense strategies based on structures are increasingly unpopular as they are costly, leave lasting scars on the landscape, and sometimes have limited effectiveness or even adverse impacts. While a clear improvement concerning aesthetic considerations using soft submerged breakwater is undeniable, their design has often focused on wave transmission processes across the crest of the structure, overlooking short- to medium-term morphodynamic responses. In this study, we used a time- and depth-averaged morphodynamic model to investigate the impact of the implementation of a submerged breakwater on surf zone sandbar dynamics at the beach of Sète, SE France. The hydrodynamic module was calibrated with data collected during a field experiment using three current profilers deployed to capture rip-cell circulation at the edge of the structure. The model showed good agreement with measurements, particularly for the longshore component of the flow (RMSE = 0.07 m/s). Results showed that alongshore differential wave breaking at the edge of the submerged breakwater drove an intense (0.4 m/s) two-dimensional circulation for low- to moderate-energy waves. Simulations indicated that inner-bar rip channel development, which was observed prior to the submerged reef implementation, was inhibited in the lee of the structure as rip-cell circulation across the inner bar disappeared owing to persistently low-energy breaking waves. The cross-shore sandbar dynamics in the lee of the structure were also impacted due to the drastic decrease of the offshore-directed flow over the inner-bar during energetic events. This paper highlights that implementation of a submerged breakwater results in larges changes in nearshore hydrodynamics that, in turn, can affect overall surf zone sandbar behavior. |
topic |
submerged breakwater morphodynamic model sandbar dynamics |
url |
https://www.mdpi.com/2077-1312/7/4/117 |
work_keys_str_mv |
AT clementbouvier modelingtheimpactoftheimplementationofasubmergedstructureonsurfzonesandbardynamics AT brunocastelle modelingtheimpactoftheimplementationofasubmergedstructureonsurfzonesandbardynamics AT yannbalouin modelingtheimpactoftheimplementationofasubmergedstructureonsurfzonesandbardynamics |
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