Eastern Scheldt Storm Surge Barrier Research Articles

Assessment of the impact of tidal power extraction from the Eastern Scheldt storm surge barrier through the evaluation of a pilot plant

Hydraulic structures can be a promising place for tidal energy extraction due to the high flow velocities, easy access to the power grid and easy access for maintenance. However, quantification of the impacts of a tidal power plant in a hydraulic structure is not straight forward. In 2015 a pilot plant consisting of an array of five Tocardo tidal turbines was installed in the Eastern Scheldt Storm Surge Barrier in the Netherlands. This pilot was accompanied by monitoring studies to verify that the operation of the plant had no adverse impact on the barrier and its surroundings. This paper presents the assessment of the hydraulic impact of the tidal power plant in the storm surge barrier based on an analysis of water level and current measurements, combined with numerical modeling and followed by an assessment of the environmental impact with emphasis on the effects on the intertidal areas in the estuary. This validation approach by a pilot plant is imperative to understand the interaction between tidal turbines and the hydraulic structure on the local scale. This understanding gives extra credibility to the predictions of the extrapolated large-scale and large array assessments which will always be fully numerical.

Hydrodynamic impact and power production of tidal turbines in a storm surge barrier

To estimate the impact on energy production and environment of tidal turbines placed in the Eastern Scheldt Storm Surge Barrier a Computational Fluid Dynamics (CFD) study has been carried out on the additional head differences induced by the turbines. The CFD model focusses on a single gate opening of the Storm Surge Barrier and includes half of the adjoining gates on either side. In this 40 m wide Gate a 1.2 MW array existing of five Tocardo T2 tidal turbines has been installed as part of a demonstration project in 2015. Transient computations of the barrier with and without the turbine array were carried out for a range of quasi stationary tidal phases. The turbines are resolved in detail as rotating equipment: real-time rotation of the turbine blades (involving the displacement of the mesh nodes in an unsteady setting) is implemented, and torque and thrust for the prescribed speed of rotation is provided as output. The results for velocity, power and thrust are compared with field experiments to validate the model. Based on these computations an estimate of the effect of turbines on the discharge capacity of the storm surge barrier is given. This information will be used to parameterize the tidal turbines in the far-field hydrodynamic model of Eastern Scheldt estuary for the ultimate assessment of the effect of tidal turbines on energy production and on the environment.

Morphological Effects of the Eastern Scheldt Storm Surge Barrier on the Ebb-Tidal Delta

The morphology of the Eastern Scheldt inlet in the southwestern Netherlands has been changing for the past 25 years in response to the construction of the Eastern Scheldt storm-surge barrier in 1986. As a result of the barrier, there has been a decrease in tidal amplitudes, tidal volumes, and average flow velocities, and there is hardly any sediment exchange through the barrier. Bathymetrical measurements of the ebb-tidal delta show multiple effects: (1) An overall decrease in sediment volume, (2) a decrease in morphological activity, (3) erosion of the shoals and sedimentation in most channels, (4) northward reorientation of channels and shoals, and (5) an increase in wave-driven features. Results from a process-based model show that the erosion is related to the wave action, and the reorientation is related to the interaction between cross-shore and alongshore tide. The steady erosive trend, combined with the decline of morphological activity, points toward a system dominated by relatively small and mostly negative bed-level changes. This system is still far from any kind of equilibrium, and is still adapting itself to the new hydraulic forcing regime, even though sediment transport capacities have decreased.

Optimal inspection decisions for the block mats of the Eastern-Scheldt barrier

To prevent the southwest of The Netherlands from flooding, the Eastern-Scheldt storm-surge barrier was constructed, has to be inspected and, when necessary, repaired. Therefore, one is interested in obtaining optimal rates of inspection for which the expected maintenance cost is minimal and the barrier is safe. For optimisation purposes, a maintenance model was developed for part of the sea-bed protection of the Eastern-Scheldt barrier, namely the block mats. This model enables optimal inspection decisions to be determined on the basis of the uncertainties in the process of occurrence of scour holes and, given that a scour hole has occurred, of the process of current-induced scour erosion. The stochastic processes of scour-hole initiation and scour-hole development was regarded as a Poisson process and a gamma process, respectively. Engineering knowledge was used to estimate their parameters.

Applications of the CPT and the electrical density probe during the construction of the Eastern Scheldt Storm Surge Barrier : Nelissen, H A M Proc 1st International Symposium on Penetration Testing, ISOPT-1, Orlando, 20–24 March 1988V2, P881–885. Publ Rotterdam: A A Balkema, 1988

Applications of the CPT and the electrical density probe during the construction of the Eastern Scheldt Storm Surge Barrier : Nelissen, H A M Proc 1st International Symposium on Penetration Testing, ISOPT-1, Orlando, 20–24 March 1988V2, P881–885. Publ Rotterdam: A A Balkema, 1988

Immersed tube tunnelling offshore: Execution of immersed tube tunnelling projects under offshore conditions, based on studies for the euroroute fixed channel link proposal

The development of the international road and railroad network has suffered from the worldwide stagnation in economy over the past years. Nevertheless, leading economists consider new, large international infrastracture projects to be a necessity for an upturn in the economy. Among these projects are a number of connections over or under sea straits, such as Gibraltar and the English Channel. With the completion of the Seikan Tunnel, Japan has already executed such a project. The study for Euroroute's fixed Channel link proposal indicated that an immersed tube tunnel is a realistic and, often, favorable solution. Thanks to the development of immersed tube tunnelling technology, the development of the offshore industry, and work on recent large projects (such as the Dutch Eastern Scheldt Storm Surge Barrier), tunnelling techniques have improved considerably. This article provides a brief comparison between bored and immersed tunnelling solutions. The article mainly focuses on hydraulic problems, dredging and immersing the tubes. The following questions are considered: What circumstances and conditions influence the applicable methods such as surveying, dredging, immersing and related equipment? What considerations must be taken into account on immersed tube tunnelling projects? Le développement de réseau international routier et ferroviaire a souffert de la stagnation économique mondiale de ces dernières années. Néanmoins, les principaux économistes considèrent que de nouveaux grands projects d'infrastructure internationaux sont une nécessité pour un retournement de l'économie. Parmi ces projets, on peut compter des liens sous et par dessus le détroit de Gibraltar et le tunnel sous la Manche. Le Japon a déja exécuté un tel projet lors de l'accomplissement du tunnel de Seikan. Cet article démontre que la construction d'un tunnel par la méthode du tube immersé est une solution réaliste et souvent favorable. Grâce au développement de la technologie du tube immersé, au développement de l'industrie offshore ainsi qu'aux travaux récents sur de grands projets (tel que la barrière Eastern Schedlt contre les raz-de-marée), les techniques tunnelières se sont considérablement améliorées. Cet article présente une comparison rapide entre les solutions de tunnel percé et de tunnel immersé. On consid principalement les problèmes d'hydraulique, de draguage et d/immersion. Les questions suivantes sont considérées : quelles sont les circonstances et les conditions qui influencent les méthodes applicables telles que létape de reconnaissance, le draguage, l'immersion ainsi que l'équipement concerné? Quelles sont les considérations qui doivent être prises en compte lors de projets utilisant le tube immersé?

Some properties of sandasphalt in hydraulic structures : Mulder, G; Nieuwenhuis, J D; Ruygrok, P A; Calle, E O F; Petschl, R O Proc 10th International Conference on Soil Mechanics and Foundation Engineering, Stockholm, 15–19 June 1981V3, P485–490. Publ Rotterdam: A. A. Balkema, 1981

Sandasphalt, or sand-bitumen, is a mixture of sand and 3 to 5 percent by weight of bitumen. Its resistance towards erosion and sand tightness renders sandasphalt a popular substitute for clay or minestone in dam constructions. Sandasphalt will probably be used in the outer shell of relatively steep abutments in the eastern Scheldt storm surge barrier in the Netherlands. For this application restrictions on the allowed deformations are added to the usual stability requirements. A recently started research programme is investigating whether sandasphalt may meet these requirements. A visco-plastic stress-strain relation was developed and built into the well-known stability analysis according to Bishop to perform more reliable stability calculations. For the estimation of deformations a similar stress-strain relation was put into the originally visco-elastic finite element programme MARC. With these tools available now an assessment can be made of the applicability of sandasphalt in hydraulic structures where restrictions are imposed on the deformations. (TRRL)