A tidal barrier for Weymouth harbour is part of proposed flood defences to protect the town from the effects of climate change, writes Tina Rowe.
The measure is one of the long-term solutions being mooted. Shorter term measures include raising the Esplanade wall and part of the harbour wall.
At the moment around 440 properties are considered to be at risk from a one-in-200-year tidal event. By 2035 it is expected the number of properties at risk would double if no action is taken. Weymouth and Portland Borough Council, the coastal defence authority, is working with the Environment Agency on studies to understand the future flood risk.
By 2126 it is estimated that sea levels could rise by up to 1.26 metres. The town centre is in effect built on a shingle spit. Tidal surges moving through the harbour mouth and into the backwater behind the spit could become an increasing threat to property.
The council's environment spokesman, Dr Ian Roebuck, whose doctorate is in ocean sciences, said yesterday the cost of works, including the tidal barrier, could be around £50 million.
He said climate change will increase the frequency of extreme weather such as the one-in-200-year storms which battered coasts this winter.
He said: "The borough council is working alongside the Environment Agency on a three-year project to improve our understanding of coastal processes, ground conditions and the implications of sea level rise in Weymouth. This will inform a longer term sea defence strategy for Weymouth Esplanade and harbour over the next 50 years."
Defences are especially important to Weymouth because part of the town lies below sea level.
Dr Roebuck said: "Looking back three to four years the Environment Agency quite rightly said the risk of flooding was such that they would object to any new developments in Weymouth town centre unless we put significant flood defences in place."
New developments in risk areas make a payment towards flood defences.
There is no suggestion that the sea would permanently overtop the existing defences by 2035, but there is a risk that waves would overtop during big storms. Dr Roebuck said he does not expect work on raising the Esplanade wall to begin until 2018-2020. Contractors working for the council are currently repairing a hole in the harbour wall following weeks of extreme storms and will carry out further emergency work for the Environment Agency, including recharging the shingle beach.
Water Minister Dan Rogerson discussed sea defences with the council on a recent visit to Dorset and the case for partnership funding was discussed.
It is hoped that the Government will provide a significant amount of the money through the Environment Agency.