Fish Migration & Salinisation
In recent years, there has been a great deal of focus on fish migration in the Netherlands. The closure of former estuaries (the Zuiderzee and the Lauwerszee) has cut off fish from their former migration routes. This has been further exacerbated by measures taken to safeguard the hinterland against future storm surges, such as the construction of engineering structures.
Water boards, amongst others, are therefore taking initiatives to restore fish migration and resolve bottlenecks. For example, discharge from sluices is being carried out in a fish-friendly manner, and fish migration facilities are being installed alongside locks. This enables fish to reach inland waters from, for example, the Wadden Sea, and vice versa.
WaterProof is carrying out studies to determine how such fish passage facilities can best be designed – for example, in terms of dimensions and shape – as well as at what times within the tidal window or during the season certain flaps should best be opened and to what extent. We are also investigating how existing freshwater-saltwater distributions in inland and coastal waters may change in the future as a result of these measures. These measures are necessary to mitigate the effects of climate change, such as further salinisation during dry summers and lower river flows.
In order to provide our partners with answers to both their design and management queries, we use 3D computational models. We first calibrate these models using measurement data which we collect ourselves where necessary. For example, WaterProof carried out 3D model calculations and also conducted measurements for the design of the Fish Migration River (VMR) in the Afsluitdijk near Kornwerderzand. The results from these data streams – derived from models and measurements – are used to determine the optimal design. In this way, the most favourable conditions for fish migration can be achieved (including sheltered zones for fish to take refuge and the creation of gradual transitions in salinity). At the same time, the IJsselmeer’s role as a source of drinking water is preserved by preventing its salinisation.
Bekijk onze Vismigratie & Verzilting projecten
Effects of Dredged Material Disposal in the Eems
The navigational channel between the Eemshaven and the North Sea needs to be dredged regularly to remain accessible to seagoing vessels. The dredged sediment is disposed of at various disposal sites, which may have an impact on the local ecology. To assess these effects, flow conditions and sediment concentrations were measured at a disposal site during sediment disposal operations. Based on these measurements and a numerical modelling study, WaterProof assessed whether sediment disposal at location P0 could have significant adverse effects on the ecology.
Research into Scour Pits
Offshore wind farms use different types of foundations depending on the site conditions. The most commonly used foundation types are monopiles, gravity-based structures and jacket foundations. In collaboration with Leo van Rijn, WaterProof investigated the expected dimensions of scour pits around offshore wind turbine foundations. The study combined physical scale experiments carried out in WaterProof’s flow and sediment basin with numerical modelling.
Impact of EMF and Underwater Sound on Harbour Porpoises
Export cables are used to connect offshore wind farms to onshore substations, from where the electricity is fed into the national power grid. Electromagnetic fields (EMF) are generated around buried export cables as a result of the electrical current flowing through them. These EMF may potentially affect marine life. The magnitude of these fields and their potential impact are still largely unknown. We therefore work with several partners on different measurement and research projects to better understand and assess these effects. Research into the potential relationship between EMF and harbour porpoise presence within the Borssele offshore wind farm is one example.
