Application of a numerical model and bathymetric inversion algorithms to enhance understanding of nearshore change

During extreme wave events, shoaling occurs farther from shore, extending the surf zone width and intensifying wave breaking (Thornton and Guza, 1983; Mulligan and Hanson, 2016). Remote sensing using digital cameras is an inexpensive way to gather continuous observations of the surf zone and calculate water depths based on phase speed. This study investigates the robustness of the newly released version of cBathy (Holman et al., 2013; Holman and Bergsma, 2021), a bathymetric inversion algorithm. cBathy is employed in moderate to energetic wave conditions using synthetic water level data generated by the non-hydrostatic numerical phase resolving model, SWASH (Simulating WAves till Shore) (Zijlema et al., 2011; Gomes et al., 2016; Fiedler et al., 2019). The overall performance results are described by the variation in root-mean-squared errors (RMSE) with significant wave height, and with depth. The results show that RMSE are dependent on water depth, significant wave height, and domain coverage by breaking waves. cBathy V2.0 consistently performs better than the preceding version, when comparing depth estimates to survey observations.