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Nearshore and foreshore influence on overwash of a barrier island

dc.contributor.authorMatias, Ana
dc.contributor.authorCarrasco, Ana Rita
dc.contributor.authorLoureiro, C.
dc.contributor.authorAlmeida, Sílvia
dc.contributor.authorFerreira, Óscar
dc.date.accessioned2017-12-18T15:51:24Z
dc.date.available2017-12-18T15:51:24Z
dc.date.issued2014
dc.description.abstractAccurate prediction of the occurrence and morphological consequences of overwash are important for coastal flood risk assessment and management. A number of morphological and oceanographic factors controlling overwash have been identified by several authors, including nearshore bathymetry. This work intends to identify alongshore variations in storm impact and evaluate the role of sub-aerial and submerged morphological variations in overwash occurrence. For this study, 24 cross-shore topo-bathymetric profiles were set on Barreta Island (Ria Formosa barrier island system, Portugal), extending from the nearshore to the lagoon level on the island backbarrier. Pre- and post-overwash surveys were made between August 2012 and April 2013. Offshore wave characteristics were obtained during overwash events including offshore significant wave height (Hs), peak period and wave direction. Wave propagation and wave parameters at breaking were obtained from SWAN model simulations. During the study period, overwash occurred both under storm conditions (e.g., Hs = 3.8 m) and non-storm conditions (e.g., Hs = 0.8 m), the latter coincident with spring high-tide. Overwash water intrusion distance across the barrier varied alongshore between 0 m (no overwash) and 40 m (reaching lagoon waters). Beach morphology was spatially variable, and changeable from one overwash episode to the next. Important morphological variations of the barrier include modification of barrier crest elevation, beach slope, and presence of swash bars in the vicinity of Ancão Inlet. Predictions of overwash occurrence were made by means of the computation of the Overwash Potential (OP), defined as the difference between the wave runup and the barrier elevation. Several runup equations were tested, and the results of obtained OP were compared to the observations of actual overwash occurrence to determine the most reliable approach. The selected predictor provided an accuracy of 88% for the identification of the locations where overwash processes occurred along the barrier. The predictions were variable alongshore due to variations in breaking waves and beach slope, which in turn are related to the existence of nearshore bars, associated with the presence of the updrift Ancão Inlet. This study proves that nearshore and foreshore morphologies have a major impact on the longshore variation of overwash distribution.pt_PT
dc.description.versioninfo:eu-repo/semantics/publishedVersionpt_PT
dc.identifier.doi10.2112/SI70-114.1pt_PT
dc.identifier.otherAUT: OFE00989;
dc.identifier.urihttp://hdl.handle.net/10400.1/10243
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.titleNearshore and foreshore influence on overwash of a barrier islandpt_PT
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage680pt_PT
oaire.citation.issue70pt_PT
oaire.citation.startPage675pt_PT
oaire.citation.titleJournal of Coastal Researchpt_PT
person.familyNameMatias
person.familyNameCarrasco
person.familyNameLoureiro
person.familyNameFerreira
person.givenNameAna
person.givenNameA. Rita
person.givenNameCarlos
person.givenNameÓscar
person.identifierR-000-116
person.identifier545203
person.identifier453264
person.identifier.ciencia-id2811-D7C1-1DE2
person.identifier.ciencia-idA31E-1703-4030
person.identifier.ciencia-id011D-31BD-C6B6
person.identifier.ciencia-id1F1C-DF44-94C9
person.identifier.orcid0000-0003-2090-6291
person.identifier.orcid0000-0002-8980-0068
person.identifier.orcid0000-0003-3117-3492
person.identifier.orcid0000-0001-9975-0036
person.identifier.ridE-9709-2013
person.identifier.ridD-2235-2016
person.identifier.ridU-9863-2018
person.identifier.scopus-author-id56260567900
person.identifier.scopus-author-id15724386100
person.identifier.scopus-author-id23667861200
rcaap.rightsrestrictedAccesspt_PT
rcaap.typearticlept_PT
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relation.isAuthorOfPublication14adf536-4f81-42de-b00f-6d1cf3b0d75e
relation.isAuthorOfPublication.latestForDiscoverydbfe713e-6ca3-4946-be23-c63049394986

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