The morphology of the East Frisian Islands and Coast has experienced enormous changes in the course of the last centuries. The resedimentation of medieval sturm bays has played a dominant role within these morphodynamical processes which could no longer only be credited to the impacts of littoral drift. Reconstructions of former coastal morphology have been used to quantify the long-term development of significant parameters for the tidal basins of the East Frisian Wadden Sea. Additionally also the tidal volumes for situations since 1650 could be determined. On this basis the long-term stability of common empirical relationships was checked.