Nearshore bathymetric inversion from video using a fully non-linear Boussinesq wave model

Abstract

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.