A 3D scale model of a Nigerian beach near Lagos has been put through its paces this month in our state-of-the-art modelling hall. New coastal defences are needed where the beach has retreated at the residential Maiyegun Beach Estate following major development farther along the coast. The designers of the coastal protection scheme, CDR International, asked us to build the model to show how the proposed sea defences would influence the response of the beach.
Constructed in one of our wave basins, the model represents an embayment between two groynes with a low crested breakwater between them. The bathymetry (or seabed) has been replicated in the vicinity of the breakwater and model sand was used to recreate the beach.
Our engineers investigated alternative designs of the low-crested breakwater structure and the response of the beach behind the structure. The scheme was tested under five sea states – the first two represented the frequently occurring conditions on the beach and the other three represented more extreme storms, with less frequent return periods. After each test the model was surveyed by a 3D laser scanner.
We have also carried out 2D modelling in one of our flumes to collect further data about the breakwater section, using a combination of wave transmission and armour stability testing.
Our leading-edge wave basins typically measure 30m x 25m with a working depth of 1.0m, although bigger basin layouts are possible. The wavemakers are equipped with active wave‑absorbing systems to reduce the effect of waves reflected from the test structures, and can generate non-repeating random sea-states to any required spectral form.
Image credit: CDR International
Find out more about our physical modelling facilities: www.hrwallingford.com/facilities/physical-modelling