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MoHDa
29th November 2006, 10:25 AM
The extended abstract of my presentation (Comparison of bathymetric changes observed by radar in different time scales) at SeaTech Week 2006 in Brest is attached.

Abstract


A basic requirement for a series of coastal and marine activities is the knowledge on the bathymetry. In the present investigation the concrete subject of interest is the assessment of local depths by analyzing radar image sequences by the Dispersive Surface Classificator (DiSC), a method to determine local maps of water depths and hydrographic parameters. This method was applied to datasets taken on different time scales at the North West side of the Sylt Island in North Sea, Germany.
Longterm investigations by radar image sequences have shown that during the period of 4 years (2000-2003) there is sedimentation within a longshore ship track and erosion in the near shore areas. This result is compared with the short term impact observed during a nine-day storm, 20-28<sup>th</sup> of February 2002.
The analyzed radar data were acquired over a coastal area of about 1km x 1km. The analyzing algorithm DiSC is based on the linear dispersion relation of the gravity waves and on the way that the waves interact with the seabed. Due to the spatial variations in the bathymetry in areas near to the coast the sea state and the tidal currents are inhomogeneous as well. For the implementation of the objective, a concrete approach has been established. As this is one of the first times that the method is used, all the parameters of the DiSC have been analyzed, tested and optimized. The results, instantaneous sea level, mean depth over a tidal cycle and determination of sediment equilibrium, of the investigation are satisfactory and under specific assumptions their accuracy is comparable with most expensive or time consuming methods.

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