Crescent-shaped sand dunes that form on the seabed, similar to those on land that are famous for engulfing a Star Wars movie set in the Sahara, do not cause increased erosion risk for offshore wind farms, according to a study by HR Wallingford.
The research, published in the latest edition of the journal Earth Surface Processes and Landforms, is the most extensive study of its kind and will help support offshore wind developers, the consultancy said.
The work captures the effects of the sedimentology phenomena, called marine barchan dunes, trooping across the seabed and looked at whether this causes increased erosion or scour around the monopiles.
The scouring process happens too quickly to observe, so the team constructed an advanced 3D numerical model using the Telemac modelling suite, HR Wallingford said.
“The team did see some surprising scour pits, but luckily for the planning, installation and maintenance of wind farms, the team of experts did not find that the barchan dune increased erosion,” the company said.
But because the scour happened so quickly, there was never any additional sand up against the monopile, keeping the stiffness and the integrity of the foundation fairly constant, it added.
HR Wallingford senior scientist Kerry Marten said: “We first spotted the dunes in 2004 during a pre-installation site survey and, realising that not much was known about how the large submarine features would interact with the wind farm, we asked the owner if we could use the data for our internal research programme.
“For the next eleven years we tracked the progress of the dune, inputting the data from site surveys into our model and analysing the effects on the monopiles.”