Title
Measuring and modelling overwash hydrodynamics on a barrier island
Author
Matias, Ana
Carrasco, Ana Rita
Loureiro, Carlos
Andriolo, Umberto
Masselink, Gerd (Plymouth University)
Guerreiro, Martha
Pacheco, A
McCall, R.T. (TU Delft Environmental Fluid Mechanics)
Ferreira, Óscar
Plomaritis, Theocharis A.
Contributor
Aagaard, T. (editor)
Deigaard, R. (editor)
Fuhrman, D. (editor)
Date
2017
Abstract
Overwash hydrodynamics datasets are mixed in quality and scope, being hard to obtain due to fieldwork experimental difficulties. Aiming to overcome such limitations, this work presents accurate fieldwork data on overwash
hydrodynamics, further exploring it to model overwash on a low-lying barrier island. Fieldwork was performed on Barreta Island (Portugal), in December 2013, during neap to spring-tides, when significant wave height reached 2.64
m. During approximately 4 hours, more than 120 shallow overwash events were measured with a video-camera (at 10 Hz), a pressure transducer (at 4 Hz) and a current-meter (at 4 Hz). This high-frequency fieldwork dataset includes
runup, overwash number, depth and velocity. Fieldwork data along with information from literature were used to setup XBeach model in non-hydrostatic mode. The baseline model had variable skills over the duration of the overwash each 30 minutes. The baseline model was forced to simulate overwash with different nearshore morphology, grain-size and lagoon water level. An average decrease of about 30% overwash was obtained due to changes in the nearshore episode, performing better during the rising tide than during the falling tide. Model average number of events RMSE (root-mean-square-error) was 7 events morphology, mostly a small vertical growth of the submerged bar. The coarser and finer grain-sizes tests produced an 11% change in overwash, with less overwash on the coarser barrier. Changing lagoon water levels had a reduced effect on overwash hydraulics.
Subject
storm impacts
video data
nearshore topography
hydrodynamics
XBeach
runup
To reference this document use:
http://resolver.tudelft.nl/uuid:93712ab1-ae0b-4c80-8180-9f53c45d4b2c
Source
Proceedings of Coastal Dynamics 2017: Helsingør, Denmark
Event
Coastal Dynamics 2017, 2017-06-12 → 2017-06-16, Kulturværftet, Helsingor, Denmark
Part of collection
Institutional Repository
Document type
conference paper
Rights
© 2017 Ana Matias, Ana Rita Carrasco, Carlos Loureiro, Umberto Andriolo, Gerd Masselink, Martha Guerreiro, A Pacheco, R.T. McCall, Óscar Ferreira, Theocharis A. Plomaritis