Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
This manuscript reports on a novel field experiment carried out on a microtidal beach in Camargue, France. For the first time in the field, a comprehensive description of the groundwater dynamics under sandy beach swash zone is presented. A cross-shore network of 15 buried pressure sensors is combined with terrestrial LiDAR measurements to study the swash-groundwater dynamics. The presented data focus on the decay of a moderate storm which allows to monitor the evolution of the groundwater pressure field in response to the retreat of the swash zone. Both horizontal and vertical head gradients are measured within the porous sand soil to estimate the groundwater flow field using Darcy’s law. Time-averaged analysis demonstrates the presence of a rather consistent groundwater circulation pattern under the swash zone, shifting offshore with the swash zone. The main tendency is an offshore directed flow, with infiltration/exfiltration in the upper/lower parts of the swash zone. Time-resolved analysis highlights the typical groundwater response to swash events which consists mainly of an overall infiltration flow during the bed inundation by the swash tongue, a seaward flow during the swash retreat and, for long backwash events, a localized exfiltration flow under the next incoming uprush.
ISSN: 0309-1708

hal-01412450
https://hal.archives-ouvertes.fr/hal-01412450
DOI : 10.1016/j.advwatres.2016.09.009

Éditeur(s) : HAL CCSD World Scientific
Résumé : The present paper presents a laboratory experiment of rip current circulations over a moveable bed. The rip current characteristics over four distinct beach morphologies, exhibiting more or less developed nature-like bar-rip morphology,were investigated. For each video run, the same off shore shore-normal waves were generated by the wave maker with the same mean water level in order to study the sensitivity of the rip current characteristics as a function of the beach morphology only. In each case, a 1-hour video run was used to track a large number (~30) of drifters released within the surf zone. Image coordinates were then rectifie d to still water level Cartesian coordinates to compute drifter velocities, mean characteristics and surf zone rete ntion rates. Results show the presence of classic rip current patterns with counter-rotating cells and a relatively narrowoffshore-directed jet with, for three of the situations, a reasonably symmetric shape. Non-surprisingly, it was found that rip current intensity increases with increasing relative depth of the rip channel. The wave-driven circulations were strongly unstable. Computed standard deviation in fl ow intensity and direction provides high resolution information on the spatial variability of the rip current insta bilities with, for instance, highly-pulsating and weakly directionally variable offshore-directed flow in the rip channel. Conversely to what was previously hypothesized in the literature, there was hardly trace of vortices being shed offs hore and drifters exiting the surf zone compartment were not systematically caught by a pulsating jet. The cause for drifter exiting the semi-enclosed surf zone compartment remains, however, elusive and deserves further investigations. The computed surf zone retention rates (~90%) were of the order of those previously observed in the field, with no clear relationship with the mean rip current velocity or relative depth of the rip channel. Further video-runs will have to be analyzed to explore potential explanations
Proceedings of Coastal Dynamics 2009 Impacts of Human Activities on Dynamic Coastal Processes

ISBN : 978-981-4282-46
hal-00854534
https://hal.archives-ouvertes.fr/hal-00854534

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
ISSN: 0022-0981

hal-01659841
https://hal.univ-antilles.fr/hal-01659841
https://hal.univ-antilles.fr/hal-01659841/document
https://hal.univ-antilles.fr/hal-01659841/file/Dromard%20et%20al-JEMBE-Hal.pdf
DOI : 10.1016/j.jembe.2012.12.011

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Resource use of seagrass herbivorous fishes Resource use by three juvenile scarids (Cryptotomus roseus, Scarus iseri, Sparisoma radians) in Caribbean seagrass beds
ISSN: 0304-3770

hal-01659844
https://hal.univ-antilles.fr/hal-01659844
https://hal.univ-antilles.fr/hal-01659844/document
https://hal.univ-antilles.fr/hal-01659844/file/Dromard%20et%20al%20Seagrass-Manuscript-HAL.pdf
DOI : 10.1016/j.aquabot.2016.08.003