Investigation of wave propagation rays in near shore zones
Andrey Pleskachevsky(1), Xiao Ming Li(1), Stephan Brusch(1) and Susanne Lehner(1)
(1) DLR, Muenchener Str.20, 82234 Wessling, Germany
The refraction of long swell at water depth smaller than 50m is caused by influence of the underwater topography in the coastal areas. Analysis of the SAR image spectra allows to obtain the peak wavelength, direction and significant wave height. A method was developed for tracking of wave rays influenced by bathymetry depending variations of swell. One application of the method is to derive underwater topography using the dispersion relation. The satellite scenes showing patterns of well developed swell allow to obtain this quite accurately, an error analysis is given. The proposed method was tested using high resolution TerraSAR-X data acquired over different areas, i.e. the Duck Research Pier (North-California, USA), Port Phillip (Melbourne, Australia) and around Helgoland Island (German Bight, North Sea).
Wave energy reaches high values during storms. To estimate its impact is an important task for coastal protection. Using wave height and wavelength derived from image spectra we applied the method to estimate the wave energy flux propagation along the wave tracks from deep water to the coastal line. We compare this to results of a numerical wave model, run at fine spatial horizontal resolution of 100m. For numerical simulation we use the wind field and swell to model mesh boundaries obtained from TerraSAR-X data. An example for the German Bight (North Sea) is shown. Storm surge cases are discussed.
The method is developed in cooperation with different organisations working on coastal protection, e.g., BSH (German Federal Maritime and Hydrographic Agency ) and BAW (Federal Waterways Engeneering and Research Institute) in Germany, in order to validate and improve the performance of their numerical models. The method is developed using TerraSAR-X data and can be transform to the upcoming Sentinel-1 mission.