Estimation of the Nearshore Bathymetry using Remote Sensing Techniques: Combining Beach Wizard and cBathy

Our understanding of nearshore coastal zone processes can be improved significantly with the availability of high spatiotemporal resolution bathymetry data. This high resolution data can be used for validation and calibration of numerical models, for providing forecasts of hydrodynamic conditions and morphological development, and for monitoring coastal evolution. Two algorithms that use remote sensing information to infer the corresponding bathymetric evolution are cBathy (Holman et al., 2013) and Beach Wizard (van Dongeren et al, 2008). cBathy models the temporal evolution of bathymetry by assimilating up-to-date bathymetry observations with a prior running average bathymetry. These bathymetry observations are determined using video-derived estimates of wave celerity via the linear dispersion relationship. Beach Wizard is a data-model assimilation scheme that works by comparing multiple sources of observed information with numerical model results. The bathymetry is progressively updated in time in order to make the observed and computed properties converge. Although Beach Wizard has the ability to use multiple sources, the main source of information it uses is video-derived roller energy dissipation. The aim of the present study was to evaluate whether a combination of the two algorithms can improve our ability to estimate the nearshore bathymetry. The method of combining the two algorithms was to use cBathy bathymetry observations in combination with roller dissipation maps as sources to the Beach Wizard data-model assimilation scheme. Results demonstrated that a possible method of combining the sources is to use cBathy bathymetry estimates as Beach Wizard sources during calm conditions and roller dissipation maps as Beach Wizard sources during stormier conditions. cBathy bathymetry estimates perform well as Beach Wizard sources in the surf zone during low energy conditions; however, performance decreases during higher energy conditions (when waves are breaking).
Hydraulic Engineering
Hydraulic Engineering
Civil Engineering and Geosciences