Analysis of Morphological Changes in a Part of the German Wadden Sea: A Comparison of Radar, Optical and In-Situ Topographic Data

Abstract

For assessing the suitability of in-situ bathymetric measurements and remote sensing satellite data (ERS-1 and 2, Landsat-TM and MSS, IRS-1C PAN and LISS-III) to detect morphological changes in tidal flats and the information content obtained by both methods, two highly morphodynamic test areas have been chosen within the Dithmarschen Wadden Sea (German Bight): the shoals Tertius Sand and D-Steert. Both sand-banks show a distinct shoreward drift, which is due to sediment motion driven by general sea level rise and hydrodynamic forces such as waves and currents. Morphological changes related to sedimentation, erosion and redeposition can be shown by analyzing in-situ data. Moreover, the shift of water level contours due to topographical changes can be quite efficiently demonstrated by comparing the contours extracted from satellite images of different years.