Browsing by Author "Almar, R."
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- ItemA new remote sensing method for high-resolution quantification of submersion regimes in wave exposed shores(2016) Flores, G.; Aguilera, José Miguel; Almar, R.; Cienfuegos Carrasco, Rodrigo Alberto; Navarrete C., Sergio
- ItemBarred-beach morphological control on infragravity motion(2012) Almar, R.; Cienfuegos Carrasco, Rodrigo Alberto; Gonzalez, Eduardo; Catalán, P.; Michallet, H.; Bonneton, P.; Castelle, B.; Suarez, L.A conceptual analysis of the coupling between bars and infragravity waves is performed combining laboratory experiments and numerical modeling. Experiments are carried out in a wave flume with a barred profile. The Boussinesq fully-nonlinear model SERR1D is validated with the laboratory data and a sensitivity analysis is performed next to study the influence on the infragravity wave dynamics of bar amplitude and location, and swash zone slope. A novel technique of incident and reflected motions separation that conserves temporal characteristics is applied. We observe that changing bar characteristics induces substantial variations in trapped energy. Interestingly, a modification of swash zone slope has a large influence on the reflected component, controlling amplitude and phase time-lag, and consequently on the resonant pattern. Variations of trapped infragravity energy induced by changes of swash zone slope reach 25 %. These changes in infragravity pattern consequently affect short-wave dynamics by modifying the breakpoint location and the breaking intensity. Our conceptual investigation suggests the existence of a morphological feedback through the action of evolving morphology on infragravity structures which modulates the action of short-waves on the morphology itself.
- ItemIntertidal beach profile estimation from reflected wave measurements(2019) Almar, R.; Blenkinsopp, C.; Almeida, L.P.; Bergsma, E.W.J.; Catalan, P.A.; Cienfuegos Carrasco, Rodrigo Alberto; Viet, N.T.
- ItemNearshore bathymetric inversion from video using a fully non-linear Boussinesq wave model(2011) Cienfuegos Carrasco, Rodrigo Alberto; Almar, R.; Birrien, F.; Castelle, B.; Catalán, P.; Michallet, H.This paper presents a new depth inversion methodology from video imagery. The strength of the method is the use of a fully non-linear Boussinesq wave model in combination with a very complete video-derived laboratory wave observation that includes period, celerity and wave height. Compared to the previous use of wave dispersion formulas, here the better description of wave dynamics substantially improves bathymetry estimation. For the considered laboratory case, error on bathymetry is as small as 8 % whereas other formulations, shallow water or non-linear derived solution can only attain 24 % and 14 %, respectively. More in-depth analysis on the error shows a fair sensitivity on video-derived breaker height and describes the large contribution of non-linearities. The recent possibility of using Serre's dispersion relation in combination with video-derived wave height provides a reasonable performance and should be further envisaged for one-dimensional depth inversion. Future extensions of this work involve the use of a two-dimensional Boussinesq model to include more hydrodynamics processes such as wave-driven circulation over three-dimensional surfzone sandbars.
- ItemRiver mouths and coastal lagoons in central Chile(2017) Cienfuegos, R.; Campino, J.R.; Gironas Leon, Jorge Alfredo; Almar, R.; Villagrán, M.
- ItemSea state from single optical images: A methodology to derive wind-generated ocean waves from cameras, drones and satellites(2021) Almar, R.; Bergsma, E. W. J.; Catalán, P. A.; Cienfuegos Carrasco, Rodrigo Alberto; Suárez Atias, Leandro; Lucero, F.; Lerma, A. N.; Desmazes, F.; Perugini, E.; Palmsten, M. L.; Chickadel, C.Sea state is a key variable in ocean and coastal dynamics. The sea state is either sparsely measured by wave buoys and satellites or modelled over large scales. Only a few attempts have been devoted to sea state measurements covering a large domain; in particular its estimation from optical images. With optical technologies becoming omnipresent, optical images offer incomparable spatial resolution from diverse sensors such as shore-based cameras, airborne drones (unmanned aerial vehicles/UAVs), or satellites. Here, we present a standalone methodology to derive the water surface elevation anomaly induced by wind-generated ocean waves from optical imagery. The methodology was tested on drone and satellite images and compared against ground truth. The results show a clear dependence on the relative azimuth view angle in relation to the wave crest. A simple correction is proposed to overcome this bias. Overall, the presented methodology offers a practical way of estimating ocean waves for a wide range of applications.
- ItemVideo monitoring and field measurements of a rapidly evolving coastal system: the river mouth and sand spit of the Mataquito River in Chile(2014) Cienfuegos Carrasco, Rodrigo Alberto; Villagrán, M.; Aguilera, José Miguel; Catalán, P.; Castelle, B.; Almar, R.