An approach to determining nearshore bathymetry using remotely sensed ocean surface dynamics: Fid-Bau Portal

An approach to determining nearshore bathymetry using remotely sensed ocean surface dynamics

Misra, Shubhra K / Kennedy, Andrew B / Kirby, James T

AbstractThis paper describes a spatially one-dimensional algorithm developed to estimate water depths from remotely sensed information of the water surface, using extended Boussinesq equations. Local phase speed estimates are obtained using a least-squares approach, from spatial profiles of surface elevation/orbital velocity lagged in time. Inversion algorithms have been developed for both linearized and fully nonlinear Boussinesq equations to calculate the depth. In all cases, synthetic input data are generated using a fully nonlinear time-dependent Boussinesq model. Wave conditions including monochromatic and irregular waves are simulated in the model. Mean flow effects are included in the inversion algorithm to account for currents. For monochromatic wave conditions, there is good agreement between the actual and estimated depth and particle kinematics. The fully nonlinear method, as compared to the linearized inversion, improves the depth prediction by 10% for the test case considered. Irregular wave conditions were simulated using time series generated for a TMA spectrum with varying values of the peak enhancement factor. The error in the inverted depths increased in the deeper part of the bathymetry as the wave train become more broad-banded. For monochromatic waves in the presence of weak currents, the modified algorithm (including mean flow effects) is seen to improve the inverted depth by 10%, over the original formulation.