Hydrodynamic and geomorphological changes in the tidal system

Abstract

The Oosterschelde has been an eroding basin for centuries. Large sand losses along the basin due to disastrous storm surges in the 15th and 16th century have increased the Oosterschelde’s tidal volume by at least 50%. More recently further changes in the hydrodynamics and the morphology of the Oosterschelde took place. These changes were due to the implementation of the Delta Project civil engineering works. The closure of the Grevelingen dam in 1964 and the Volkerak dam in 1969 increased the tidal volume in the Oosterschelde with 6%, which caused a considerable erosion and widening of the channels in the western part and the north-eastern branch of the Oosterschelde. Parallel to the basin erosion a distinct sedimentation at the Oosterschelde’s outer delta took place. The morphological adaptions were still in progress during the construction of the Oosterschelde works. The erosion inside the basin and the expansion of the outer delta stopped when the storm-surge barrier and two auxiliary dams significantly reduced the tidal volume in the basin.