Long-term morphodynamic evolution of Texel Inlet and its ebb-tidal delta (The Netherlands) (original) (raw)
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Netherlands Journal of Geosciences, 2017
Tidal inlets and the associated ebb-tidal deltas can significantly impact the coastal sediment budget due to their ability to store or release large quantities of sand. Nearly 300 million m3 (mcm) of sediments were eroded from Texel Inlet's ebb-tidal delta and the adjacent coasts following the closure of the Zuiderzee in 1932. This erosion continues even today as a net loss of 77 mcm was observed between 1986 and 2015. To compensate, over 30 mcm of sand has been placed on the adjacent coastlines since 1990, making maintenance of these beaches the most intensive of the entire Dutch coastal system.Highly frequent and detailed observations of both the hydrodynamics and morphodynamics of Texel Inlet have resulted in a unique dataset of this largest inlet of the Wadden Sea, providing an opportunity to investigate inlet sediment dynamics under the influence of anthropogenic pressure. By linking detailed measurements of bathymetric change to direct observations of processes we were abl...
Marine Geology, 2021
The estuaries in the SW Netherlands, a series of distributaries of the rivers Rhine, Meuse and Scheldt known as the Dutch Delta, have been engineered to a large extent. The complete or partial damming of these estuaries in the nineteensixties had an enormous impact on their ebb-tidal deltas. The strong reduction of the cross-shore tidal flow triggered a series of morphological changes that includes erosion of the ebb delta front, the building of a coast-parallel, linear intertidal sand bar at the seaward edge of the delta platform and infilling of the tidal channels. The continuous extension of the port of Rotterdam in the northern part of the Haringvliet ebb-tidal delta increasingly sheltered the latter from the impact of waves from the northwest and north. This led to breaching and erosion of the shore-parallel bar. Moreover, large-scale sedimentation diminished the average depth in this area. The Grevelingen ebb-tidal delta has a more exposed position and has not reached this stage of bar breaching yet. The observed development of the ebb-tidal deltas caused by restriction or even blocking of the tidal flow in the associated estuary or tidal inlet is summarized in a conceptual model. This model can help to assess the impact of interventions in other systems, for instance to mitigate the impacts of sea-level rise.
Morphodynamics of ebb-tidal deltas: a model approach
Estuar Coast Shelf Sci, 2003
The results of 2DH numerical models of the Frisian Inlet (located in the Dutch Wadden Sea) are discussed to gain further knowledge about the physical mechanisms causing the presence of both ebb-tidal deltas and of channels and shoals in tide-dominated inlet systems. A hydrodynamic model, extended with sediment transport formulations, was used to verify earlier conceptual models that deal with ebb-tidal delta characteristics. The model does not confirm their hypothesis concerning the observed spatial asymmetry of ebb-tidal deltas and suggests that long-term morphological simulations are needed to understand this aspect. Furthermore, the model indicates that the initial formation of the ebb-tidal delta is mainly due to convergence of the tidally averaged sediment flux related to residual currents, whilst the net sediment transport in the basin is mainly caused by tidal asymmetry. A second model (accounting for feedbacks between tidal motion and the erodible bottom) was used to simulate the long-term bathymetric evolution of the Frisian Inlet under fair weather conditions. This model reproduces the gross characteristics of the observed morphology: the presence of a double-inlet system with two distinct ebb-tidal deltas having different sizes and the presence of channels and shoals. The role of the 'Engelsmanplaat', a consolidated shoal in the middle of the Frisian Inlet, was not found to be crucial for the morphodynamic stability of this inlet system.
This paper presents an overview of the Dutch Wadden Sea from a sedimentological point of view. After the pioneering work of scientists new impulses to this kind of research are being given by the need for detailed recent analogues of fossil hydrocarbon-containing rock successions and by the great concern about the future of our coastline in relation to accelerated sea-level rise. After many studies of a descriptive nature in the past, there is now a growing tendency so a more dynamical view to the Wadden Sea system. There is a strong interdependence between various tidal sub-environments within individual inlet systems. Together these sub-environments form so-called Sand Sharing Systems, whose behaviour is largely defined by the tidal prism and the wave climate. Such a dynamical approach may greatly facilitate the research and understanding o fossil barrier-related sediments. Apart from the physical processes the abundant biota plays also an important role in the sedimentological development of the Wadden Sea. The large amount of data on the development of the Wadden Sea in pre-historical and historical times, moreover, allows to test hypotheses about the evolution of the system on the scale of centuries to millennia.
Island-terminus evolution related to changing ebb-tidal-delta configuration: Texel, The Netherlands
Marine Geology, 2006
Historical maps of southwest Texel and the adjacent ebb-tidal delta, supplemented with quartz OSL (Optically Stimulated Luminescence) ages of dune sand, span four centuries and show several links between coastal development and ebb-tidal-delta behavior. Updrift inlet migration governed recurved-spit formation, and changes in ebb-tidal-delta size and shape resulted in the formation of a bulge at the island terminus. Sustained updrift migration of the ebb-tidal delta resulted in a commensurate position shift of the bulge and eventually in flattening of the coastline. Regional coastal-management measures have had a strong influence on tidal-inlet and ebb-tidal-delta behavior, and therefore also on the changing shape of southwest Texel. Identification of relationships between ebb-tidal-delta behavior and changing barrier-terminus erosion-and-accretion patterns on a decadal to century time scale contributes to our understanding of coastal-system dynamics. Any barrier terminus with preserved sets of dune ridges holds a potential record on past ebb-tidal-delta orientations, which provide clues on past changes in tidal prisms and wave versus tide dominance. Under the current ebb-tidal-delta configuration, the entire westward-oriented coast of southwest Texel is too exposed for lasting accretion. Bulges resulting from future merger of shoals with the coast in this area will be eroded rapidly.
Netherlands Journal of Geosciences, 2016
The estuaries in the SW Netherlands, a series of distributaries of the rivers Rhine, Meuse and Scheldt known as the Dutch Delta, have been engineered to a large extent as part of the Delta Project. The Voordelta, a coalescing system of the ebb-tidal deltas of these estuaries, extendsc.10 km offshore and coversc.90 km of the coast. The complete or partial damming of the estuaries had an enormous impact on the ebb-tidal deltas. The strong reduction of the cross-shore directed tidal flow triggered a series of morphological changes that continue until today. This paper aims to give a concise overview of half a century of morphological changes and a sediment budget, both for the individual ebb-tidal deltas and the Voordelta as a whole, based on the analysis of a unique series of frequent bathymetric surveys. The well-monitored changes in the Voordelta, showing the differences in responses of the ebb-tidal deltas, provide clear insight into the underlying processes. Despite anthropogenic ...
North-Coast of Texel: a comparison between reality and prediction
1998
For an efficient protection of the north coast of the Dutch Waddensea island Texel, a long dam was constructed in 1995. The position of this dam is on the southern swash platform of the ebb tidal delta of the Eijerlandse Gat: the tidal inlet between the two Waddensea islands Texel and Vlieland. The long dam changed the hydro-morphological conditions in this tidal inlet. The changes in the inlet's morphology have been monitored through regular bathymetry surveys. This paper describes some of the most remarkable changes that occurred in the inlet after the construction of the long dam. The impact of the long dam on the inlet's morphology and the adjacent shoreline stability has been examined with the use of a medium-term morphodynamic model. From a comparison between the observed and predicted morphological changes it followed that the model was able to simulate the large scale morphological response of the inlet system. However, on a smaller scale there were still important discrepancies between the observations and the predictions.
Morphodynamics of a storm-dominated, shallow tidal inlet: the Slufter, the Netherlands
Netherlands Journal of Geosciences, 2012
In this article we study the morphodynamics of the Slufter on the short-term (months) and long-term (years to decades). The Slufter is a small, shallow tidal inlet located on the island of Texel, the Netherlands. A narrow (tens of meters) channel connects the North Sea with a dune valley of 400 ha. This narrow channel is located in between a 400-700 m wide opening in the dunes. Approximately 80% of the basin of the Slufter is located above mean high water level and is flooded only during storms, when a threshold water level is exceeded.Analysis of historical aerial photographs revealed that the inlet channel migrates about 100 m per year. In the 1970's it migrated to the south, while since 1980 it is migrating to the north. When the channel reached the dunes at the north side of the dune breach the channel was relocated to the south by man. The channel inside the backbarrier basin was less dynamic. It shows a gradual growth and southward migration of a meander on a decadal time ...
Morphodynamic modelling for a tidal inlet in the Wadden Sea
Marine Geology, 1995
A dynamic model for morphological development in a tidal inlet, "Het Friesche Zeegat", in the Wadden Sea along the northern coast of the Netherlands, is set up to obtain a better understanding of the behaviour of the morphological system around tidal inlets. The model is based on DELMOR, a program package for morphological changes, developed at Delft Hydraulics. Computations of the flow, the sediment transport, the initial bed level change rate as well as long-term morphological development have been carried out. The model has proven to be a useful research tool, even though it does not yet reproduce reality in detail.