Application of a data-model assimilation method to a 3D surf zone sandbar physical experiment

Abstract : Video imagery recently arose as a low-cost alternative to direct measurement to estimate wave characteristics and then tackle the lack of actual updated bathymetries hydro-morphodynamic coupled numerical models typically face. Nonlinearities that are ubiquitous over complex three-dimensional surfzone sandbars are a key problem for observation relevance, and feed an increasing need of local wave information. Therefore, a close interaction between video imagery and modeling is highly required through observation assimilation. In this paper, we explore two bathymetry inversion methods related to an original experiment on nature-like beaches. Wave celerity was first video-estimated and depth inversion was performed to quantify the underlying bathymetry. While existing methods were previously tested over rather alongshore-uniform barred beaches, here we show that the efficiency of such method strongly decreases with increasing beach alongshore non-uniformity. A data-model assimilation, based on a Kalman filter, was further developed and applied to our experimental study using bathymetric data that derived from wave celerity estimates. Analytically set Gaussian-type covariance matrices were inverted to provide local correction. The method shows promising skills to correct bathymetry with the single source of bathymetric video proxy and now required further in-depth improvement.
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https://hal.archives-ouvertes.fr/hal-00648469
Contributor : Hervé Michallet <>
Submitted on : Monday, December 5, 2011 - 6:12:47 PM
Last modification on : Saturday, April 20, 2019 - 1:59:51 AM

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Florent Birrien, Bruno Castelle, Vincent Marieu, Rafael Almar, Hervé Michallet. Application of a data-model assimilation method to a 3D surf zone sandbar physical experiment. Journal of Coastal Research, Coastal Education and Research Foundation, 2011, SI 64, pp.976-980. ⟨hal-00648469⟩

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