Morphological Development of the Rif and the Engelsmanplaat, an Intertidal Flat Complex in the Frisian Inlet, Dutch Wadden Sea

The Rif and the Engelsmanplaat form together a suprato intertidal flat-complex at the fringe of the ebb-tidal delta and the back barrier area in the Frisian Inlet, located between the Dutch Wadden Sea Islands Ameland and Schiermonnikoog. The complex divides the Frisian Inlet into the Pinkegat Inlet in the west and the Zoutkamperlaag Inlet in the east. During the last decades the Engelsmanplaat has been suffering from serious erosion. This paper presents a study meant to find the causes for the recent erosion, especially to answer the question if the erosion is related to the human interferences in the area. The study is based on literature survey, data analysis and modelling of hydrodynamic processes. It is concluded that the recent erosion fits into the pseudo-cyclic development of the intertidal flat complex. However, the period of erosion may have been longer than normal and the rate of erosion may have been higher than normal. It is also concluded that such abnormal development is probably effects of the closure of the Lauwerszee in 1969 and not due to land subsidence caused by gas mining.