More than ever, climate change is putting flood risk management under pressure. Every year, an average of 7000 people in the world lose their lives in floods (source: UNESCO). The economic damage has now reached 22 billion euros a year and it can only increase if we do nothing. To live in safety and to keep our feet dry – while keeping costs manageable – new, innovative measures are needed. For example, alongside ‘hard’ barriers, ‘soft’ measures that use natural processes can also provide solutions. Too little is still known about many innovative solutions. Full-scale tests in the Delta Flume can fill this gap.
Waves up to 4.5 metres high
Construction work on the new Delta Flume began in September 2012, with Ballast Nedam Infrastructuur as the contractor. The new flume is 300 metres long, 9.5 metres deep and 5 metres wide. This length is needed to simulate wave formation on gradually rising coasts. The depth makes it possible to generate waves up to 4.5 metres high. Waves this big cannot be generated anywhere else in the world. This major advance requires a 10-metre-high wave board ( supplied by the American company MTS) that will be moved to and for using hydraulic cylinders.
Nine million litres of water
A water reservoir containing 9 million litres of fresh water is located alongside the new Delta Flume. That is the equivalent of four Olympic swimming pools (50 x 25 x 2 metres). The reservoir is situated underground parallel to the flume. There will be three pumping stations with a capacity of 1000 litres a second to pump the water between the reservoir and the flume. That can also be done during testing, making it possible not only to generate high waves, but also to simulate variations in the water level of the kind caused by storm surges and tides. That is important for studies of, for example, dike revetments.
The Delta Flume allows Deltares to carry out research for national and international clients, and public and private bodies. Our leading clients include the Dutch Ministry of Transport and Public Works (Rijkswaterstaat), the EU, contractors, energy utilities, developers of renewable energy concepts and concrete factories.
Designs for flood defences, dunes or breakwaters can be tested in the Delta Flume so that clients can ultimately select the best, most cost-efficient, and future-robust solution. Also, the Delta Flume is very equipped for testing of wave loads on offshore structures such as wind turbines, oil platforms and the protection of cables and pipelines.
Types of research
The Delta Flume can be used for studies in which major factors affecting the results include not only large water movements but also the detailed flows in small spaces between stones and sand or clay. It is not easy to establish a clear picture of how these things work at small scales. These types of test can now be conducted at full scale in the Delta Flume. Typical measurements in the Delta Flume will look at wave heights, wave pressures and forces, flow velocities, wave overtopping, damage patterns and changes in cross-sections.
- Overall length approximately 291m
- Width: 5 m
- Depth: 9.5 m
- Full stroke: 7 m
- “Dry-back”, piston-type wave board drive (cradle, 4 pistons)
- Second-order wave steering system
- Active Reflection Compensation
- Installed electric power for wave generation: 1.9 MW
Wave machine design and supplier MTS (USA)
- Wave characteristics
- Maximum height (regular) H max,r: 3.3 m
- Maximum wave height H = 4.5 m
- Maximum significant wave height H m0: 2.2 m
- Wave peak period (H m0 = 2.2 m): 5.7 s < Tp < 13.4 s
- Wave period 1 s < T < 20 s.
- Reservoir (length, width, depth equal to flume dimensions).
- Pumps between flume and reservoir to simulate tides or wind surge and to fill or empty different parts of the flume. Measurement cavity (width 9 m, depth 10 m, length 1.5 m).
- Flume gantry crane (2 pulley arrays, 125 kN each).
- Pull/measurement trolley (maximum speed 1 m/s and pulling power of 10 kN).