Parts of the coastline should be abandoned to the sea, but planners are avoiding making the right decisions because there is no legislation to allow them to compensate the owners who face ruin as a result.
David Carter, a lecturer at the University of Portsmouth, researching for the Ministry of Agriculture, said new legislation was needed to provide compensation for those whose land and homes needed to be abandoned to the sea in the public interest.
He said rising sea levels and more frequent storms meant it was more and more difficult and expensive to defend parts of the coast. Improvements in science also showed that extra defences in one area meant erosion in others so those adversely affected should receive compensation.
"I am not a lawyer but if there was a planning decision which caused my house to fall in the sea or my land to flood then I think I would have cause to sue," he added.
He said a test case was Medmerry Beach at Selsey, near Chichester, where the largest caravan site in Europe - which had 10,000 residents in the summer - was sheltering behind a shingle beach that was being washed away by the sea. Each year the environment agency was waging a losing battle against the elements by spending £500,000 a year replacing shingle on the beach.
"Basically the right thing to do is let the shingle beach move inland. Eventually the sea will win, but there is no proper way of compensating those who suffer."
The environment agency, which spends £19.2m a year on sea defence, said it was hoping for permission from the Ministry of Agriculture to move back the line of Medmerry Beach. "Three homes will be lost and part of the caravan site and it will cost millions to complete but at least we will have a beach we think we can hold," said a spokesman.
Dr Carter, who is researching the success of new 10-year plans for coastal defence for the ministry, said a lot of radical decisions needed to be made to retreat from the sea. Unstable cliffs could not be defended and must be allowed to fall into the sea and low-lying land in north Kent, Essex and Norfolk must be abandoned to allow salt flats to develop. Small schemes, mostly in harbours such as Chichester, had already been successful but they were needed on a much larger scale.
A second serious problem was developments which were allowed where there were no adequate sea defences. An example was Sovereign Harbour on Pevensey Bay in east Sussex, where hundreds of houses were still being built but were in danger of inundation by the sea. Fellow researcher Jane Taussik, from the same university, said councillors often overruled the advice of coastal engineers, their own officers, and the environment agency and allowed development in dangerous places.
"The recent floods have been eye-opening as far as the devastating effects that bad planning decisions can have. We have not been careful about the safeguards we need to take in tidal areas, either. We need to make a condition of developments that flood mitigation measures are put in place. Builders should be told houses cannot be sold or moved into until defence works are completed.
"When people are buying houses on the coast they should check on the risk. People often expect local authorities to tell them of the dangers but no one does. It is the house owner's or buyer's responsibility. It is not a question solicitors ask on searches, it is 'buyer beware'."