Smart dike reinforcement using smooth block revetments
Dozens of kilometres of dike are strengthened every year in the Netherlands. In collaboration with Rijkswaterstaat, the water management authorities and commercial parties, Deltares is looking at whether smooth block revetments are a smart solution. This involves using heavy concrete pillars or blocks that are positioned close to one another on the dike, preventing damage by waves. The more effective use of smooth blocks saves money, it is good for the environment and it reduces local disruption. Deltares is conducting tests in the Delta Flume to see how smooth blocks can be used optimally.
Testing stability and wave run-up
The comparative study looks at the stability of smooth block revetments when they are subjected to high waves and at how smooth blocks mitigate wave run-up. The blocks must not shift position or get damaged when waves hit the dike. The scale tests are being conducted in the Delta Flume, where waves of almost two metres can be generated. With what we learn about the unique properties of the various types of block, we can produce the optimal design for every situation.
New knowledge to produce more precise designs
The new knowledge about the mitigation of wave run-up will open up the way to more precise designs. The results will allow us to optimise national computing models, possibly eliminating the need for some dike upgrades. Learning more about the stability of various types of block makes it possible to calculate how thick the smooth block layer needs to be. If the study shows that blocks are stronger than thought previously, the amount of concrete used to produce them could be reduced. In addition, fewer dike upgrades will be required and the dikes will continue to comply with the safety standards for longer. That will cut disruption for the people living immediately alongside the dikes.
Collaboration between government and business
The striking feature of the comparative study of smooth block revetments for dikes is the intensive collaboration between the public and private sectors. Deltares teamed up for this research project with:
- Fryslân water authority
- Noorderzijlvest water authority
- Hunze and Aa’s water authority
- Afsluitdijk barrier dam project
- Sea Defences project bureau
- Various producers of smooth blocks
The three water authorities from the north of the country will use the results to devise promising solutions that will have administrative support. This will be done as part of the Trans-project Wadden Sea Dikes Review in the National Flood Protection Programme.
www.rijkswaterstaat.nl/onderzoekzetstenen (in Dutch)