Innovative Wave Study on Rock Sea Defences

Whilst it has been apparent for a long time that some forms of and fashions of rock bunds seem more effective than others in contesting erosion, it has yet to be fully understood why this should be so, or exactly how different rock platforms dissipate the power of waves, and to what degree.

A team from Plymouth University are now investigating this working alongside Bangor University, the University of Auckland in New Zealand and Deltares in the Netherlands.

The project, called WASP, an acronym for ‘Waves Across Shore Platforms), is being funded by a grant of £340,000 from the Engineering and Physical Sciences Research Council (EPSRC) for a two-year research programme that will see Plymouth University working alongside Bangor University, the University of Auckland in New Zealand and Deltares in the Netherlands. The researchers, led by Gerd Masselink, professor of coastal geomorphology at Plymouth University and his coastal processes research assistant, Dr Timothy Poate have been busy by placing specialist pressure pads and laser equipment, later video cameras, across the difficult-to-reach inlet tucked under Devon’s Screda Point. The team has previously worked on a number of major studies analysing the impact of waves on sandy and gravel beaches but this is the first time that they or any body have studied how wave energy dissipates over different kinds of rock platform.

“They are the key because every pair gives us a completely different measurement,” said Professor Masselink. “The second piece of kit is the video cameras which are looking at both the deep water section and the shallow part of the beach – they give us information on where the waves are breaking”.

“Then we have current metres — they acoustically measure the flow velocities as the tide comes across the rock platform. And the fourth piece of equipment is the laser scanner at top of beach which scans the area and tells us how high the waves run up — this gives us an idea of what energy they have. Basically, what this is all about is the story of the demise of a wave,” said the professor.

“Higher sea levels — as predicted with the continued onset of climate change — and perhaps also more stormy conditions, will undoubtedly pose a greater risk to our coasts,” said the Professor.

“This study will enable us to predict and demonstrate how sea conditions might impact on our rocky coastlines in future decades and centuries, providing a greater understanding of the potential threats we might face. “By doing this, we can formulate better adaptive strategies to deal with coastal erosion, for example through developing innovative methods to protect against coastal erosion. The project will also help us to better understand the long-term evolution of coastal cliffs.”

“At the moment there’s no computer model or equation or a tool with which you can do this because most of the coastal research has been done on sandy beaches. But what’s critical is the roughness of what is in front of the seawall. The more rough it is, the more energy loss you’ll see in the wave”.

The team hope to deliver a tool which can be used to predict how much dissipation there is across rough areas of beach, by quantifying the roughness and relating it to the wave energy that’s taken out.

The Western Morning News of October 29th 2014 gives the full story under ‘Ground-breaking wave study could help pave the way for UK sea defences of the future’ that can be seen by visiting www.westernmorningnews.co.uk/Ground-breaking-wave-study-help-pave-way-UK-sea/story-23690637-detail/story.html

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