Monitoring in the western part of the Dutch Wadden: Sea—sea level and morphology

Abstract

This paper deals with the methods and results of monitoring sea level (tidal gauges) and with the analysis of depth sounding data. Possible future monitoring by means of remote sensing techniques will be presented. Some trends, based on water level and morphological monitoring, have been established in the western part of the Dutch Wadden sea: (a) the relative mean sea level is rising persistently by 15 cm/century, observed since the middle of the 19th century. The tidal range is increasing as well; (b) the cross-sectional areas of the most western Dutch Wadden tidal inlets have been increasing over the last two centuries; (c) the intertidal zones of the Texelstroom and Vliestroom tidal basins have shown an increase of surface area over the last decades. The Borndiep tidal basin shows a decrease of 4 % of the area shallower than 5 m -Dutch Ordinance Level (DOL) over the last two centuries. Several factors prevent serious predictions about future morphological developments of the tidal Wadden flats: ~a) man induced interfering factors, e,g, the construction of the harbour revetments of Den Helder, the construction of the Enclosure Dike and construction of sand drift dikes stabilising the Wadden islands; (b) the limited scope of the present analysis that deals only with the western part of the Dutch Wadden Sea.

New data from terp excavations on sea-level index points and salt marsh sedimentation rates in the eastern part of the Dutch Wadden Sea

“…These differences are related to the geography of the North Sea coast and the location of the amphidromic points in the North Sea. MHW in the western part of the Wadden Sea was even lower before the Afsluitdijk (Enclosure Dike) closed off the Zuiderzee in 1932 (Misdorp et al, 1989). The higher tidal range and MHW indicate that the tidal energy in the eastern part of the Wadden Sea must be considerably higher than in the western part.…”

Integration of in-situ and multi-sensor satellite observations for long-term water quality monitoring in coastal areas

“…Effective monitoring of this area needs continuous tracking of the spatio-temporal variations of WCCs in order to capture information on dynamic events, which might have a substantial impact on ecosystems, such as changes caused by storms or unexpected phytoplankton blooms (Zevenboom et al, 1991). However, the climatological conditions of the Dutch Wadden Sea, characterized by frequent cloudiness, various combinations of three WCCs, besides the tide-modulated shallowness of the water, make this region a complex case study for water quality monitoring using remote sensing approaches (Arabi et al, 2019;Hommersom et al, 2010aHommersom et al, , 2010bMisdorp et al, 1989;Müller et al, 2016).…”

Predictive ecosystem research in the Wadden Sea

“…The relative proportions of habitat sizes have changed. The slope from high tide line towards the subtidal gullies steepened, because the dikeline moved seaward and the gullies became wider (Misdorp et al, 1989). (1) In spite of sea-level rise, there are no more landward extensions of the Wadden Sea.…”