Sand dunes on the northern coasts of Devon and Cornwall have been eroded by up to 15 metres in the past 15 years, according to new research.
A study by members of the Coastal Processes Research Group at the University of Plymouth demonstrated that the vast majority of coastal dunes in the South West experience chronic erosion.
Using survey data from 25 dune systems they found that they have been retreating at an average rate of 0.5 to 1 m per year, with only a few dunes in relatively sheltered locations being stable or growing.
This equated to a total retreat over the 15-year period of anything between five and 15 m, with the three worst affected locations being Westward Ho! in North Devon, and Porthcothan and Porthkidney in North Cornwall.
Writing in the journal Marine Geology, the researchers say that for half of the retreating systems, the amount of sand within the dunes has actually increased.
This means sand from the dune face, as well as from the beach, is being transported over the top of the dunes by a combination of wind and waves, and causing the dune system to migrate landward.
This is referred to as 'dune roll-over', and means there will be no immediate loss of dune habitat. However, if the dune is pushed back into coastal infrastructure or defences it will be squeezed and that could reduce the dune area.
Professor Gerd Masselink
Gerd Masselink, Professor of Coastal Geomorphology at the University of Plymouth, is the study's lead author. He said:
"Dune systems are natural forms of coastal defence. However, they are expected to exhibit increased erosion rates as a result of climate change, notably through sea-level rise and, potentially, increased storminess. It is really important to allow the dunes to migrate as this will preserve valuable coastal habitats and enhances coastal resilience. However, coastal authorities and communities are generally reluctant to allow the coastal zone to be pushed back and prefer to keep the coastal line where it is. We will have to get used to the idea that climate change will push our coastal systems slowly landward and we need to adapt to and not resist this, wherever we can."
Coastal Processes Research Group
The Coastal Processes Research Group is an internationally recognised group of researchers, specialising in field studies of coastal processes and seeking to understand and predict the behaviour of coastal and estuarine systems. Research topics include:
- beach morphodynamics and nearshore sediment transport
- coastal erosion and storm impacts
- video monitoring of coastal systems
- coastal process modelling
- estuarine processes and evolution.
The group operates a research-informed consultancy Coastal Marine Applied Research.
Making Space for Sand
The University is now working with Cornwall Council and a number of other partners on a major project to enhance the sustainability of the county's sand dunes.
The £6million Making Space for Sand initiative is being funded by Defra as part of the Flood and Coastal Resilience Innovation Programme, which is being managed by the Environment Agency.
The project aims to designate and preserve sand dunes on the Cornish coast so that coastal settlements and economies can be protected against coastal erosion and sea level rise.
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