Shore and Bed Protection Structures
The interface of land and water has always played an important role in human activities; settlements are often located at coasts, river banks or deltas. When the interface consists of rock, erosion is usually negligible, but finer material can make protection necessary. In a natural situation, the interface moves freely with erosion and sedimentation. Nothing is actually wrong with erosion, unless certain interests are threatened. Then the erosion has to be stopped. The erosion can be stopped by soft engineering solutions like sand nourishment (possibly aided by vegetation), or by a hard protection consisting of heavy material that is resistant to erosion. A hard protection can have an impact on the natural or scenic value of the coast, or can exacerbate erosion on adjacent stretches of coast, but it typically takes less space than a soft protection measure.
Also the entrances to ports have to be protected against wave action and siltation. For that purpose also protective structures are needed.
Often coastal structures built for other purposes (e.g. piers and quay walls) increase the wave and/or current load on the surrounding bed and shoreline, resulting in scour. Scour often leads to an unsafe situation for the original structure.
Examples of shore protections are riprap revetments, dike revetments with concrete blocks, breakwaters, and groynes. Bed and scour protection structures usually consist of loose rock or fascine mattresses with geotextile. Materials that can be used are for example rock or loose concrete elements. But also vegetation can be used for this purpose.
This research group studies and teaches the interaction between water motion (by waves and currents) and the protective structures. The goal is to increase the understanding of the physical processes and to translate them to design requirements for the protection of shores, banks and the seabed. Also the interaction between currents/waves and vegetation is part of the research of this group. In case of scour it is important to determine the magnitude of scour and to develop protection methods against scour.
Research focusses on improvement of these structures (make them more economic, more reliable and more environmentally friendly). Research goals are set in close cooperation with industry.
Dike revetment with concrete blocks
A breakwater under construction (by DMC)