Analysis of morphodynamical processes with a nautical X-band radar

Abstract

The morphodynamic processes in coastal areas are affected by tidal currents and the sea state leading to a transport of sand along the seafloor. Morphodynamic changes can be observed by radars. Radars image the small scale roughness at the sea surface. The backscatter indirectly depends on the bathymetry. It is known from the analysis of satellite images that the observable signatures depend on the tidal currents and the wind situation. The aim of the study is to investigate this processes in detail. The advantage of using a ground based radar in comparison to other observing instruments is the possibility of continuous observation over a long time period. The radar was mounted near the lighthouse List West on the island of Sylt in the German Bight. The presented radar images show List West, the Lister Landtief, and parts of the Lister Tief. The motivation for the observation of the coastal area at Sylt is its high morphodynamical activity. A sand bar between the Lister Landtief and the Lister Tief is in process of breaking, which will change the flood stream situation dramatically. The instrument used for the observation is a ground based nautical X-band radar with horizontal polarisation. The radar was mounted from February to June 1997 observing an area of a radius of approximately 2 km. During the observation period measurements were taken hourly.