Topographic mapping of Wadden Sea, with SAR images and waterlevel model data

The waterline method is used to derive the topography of the tidal flats along the German coast by evaluation of SAR (Synthetic Aperture Radar) images. A series of SAR images taken at different water levels from 1996 to 1999 and 2009 is analyzed with a wavelet based edge detection algorithm to identify the border between the tidal flat and adjacent water areas. The waterlines detected are combined with corresponding water-levels to represent the topography on a irregularly spaced grid. The water levels are provided from a numerical tidal model and corrected by gauge data. Topographic maps of the inter tidal zone are produced after interpolating these data into a regular grid. We reproduced the maps from 1996 to 1999 and newly processed the data from 2009.