Sea-Level Changes and Tidal Flat Characteristics

Abstract

When the greenhouse effect would result in an acceleration of the mean sea-level rise, it is of crucial importance for the coastal areas of the southern North Sea whether or not the mean height of the tidal flats will rise accordingly. If not, coastal protection in areas behind tidal flats will have to be adapted, since wave energy will no longer be dissipated in front of the coastline and will attack the protective dikes heavily.

An analysis of long-term data of tidal flat heights and a comparison with the sea-level rise have been carried out, including data from ~ 200 continuous and temporary tide-recording stations along the Dutch, German, and Danish coast. The results demonstrate a spatially more or less horizontal mean sea level (MSL). Its rise during this century varied between 10 and 20 cm per 100 y. Not any acceleration of this rise during the last decade has been recognized. The tidal range, however, did increase during the last two decades.

A significant height change of the tidal flats parallel to the rising sea level has not taken place. If the rate of global sea-level rise would increase rapidly in the future, the mean tidal flat height might even be reduced, due to both increasing turbulence and higher wave and current energy with rising water levels.