Accelerating sea level rises could see a new tidal barrier built, costing as much as £10bn on the Humber to protect vast swathes of farmland, homes and businesses.
The last time a barrier was seriously considered was back in the 1980s, but with sea levels rising faster and the threat of a far more devastating tidal surge than the one in 2013, it is back on the cards.
Work is starting on a feasibility project, led by US engineering firm Jacobs, using the Thames Barrier - one on the Humber would be four times larger - as a starting point.
The surge of 2013 flooded 7,000 hectares of land and 1,100 homes and businesses, and caused hundreds of millions of pounds damage, but only a few centimetres more would have seen much wider flooding, including in Hull.
A barrier - which could protect 500,000 people and could cost between £5bn and £10bn -could become the option of choice if rising sea levels means conventional approaches - like building higher defences - are no longer viable.
Humber Strategies Manager Philip Winn said: “Sea level rise is likely to be an enormous factor here, at the moment it’s about 5mm a year (quarter of an inch), but it is rising at an increasing rate - by 2300 potentially up to 4m.
“By 2050 there’s probably only 300mm or a foot, but by 2100 we might be talking 1m. We are just now starting to do specialist early work looking at a barrier, what kind of structure it might be and where might it be.
“In the 1980s they looked at barriers around the country, including on the Humber for power generation, but this is the first time it has been looked at for flood management.
“It would be a huge engineering undertaking, you have to think where is the best spatial location, what is the underlying geology, what are the environmental issues. The whole of the estuary is designated and I would expect it will still be protected after Brexit.
“There are navigation issues and Spurn is also vitally important as a natural flood management structure. You would have to look a the effects further down the coast and erosion.”
Mr Winn stressed that work was at a very early stage and the idea could be “parked” following the feasibility study.
James Copeland, senior environment and land use adviser for the NFU, said a barrier would be their preferred choice and show that the Humber was “open for business.”
“This one reduces the risk most, therefore it is the most attractive,” he said.
The tidal barrier is one of three options being considered as part of a revised Humber Strategy, which involves a dozen councils and goes as far inland as Gainsborough, Selby and Doncaster.
Letters are going out to 2,000 landowners around the Humber estuary flagging up the major changes which could affect their land from rising sea levels and tidal surges.
“Containing the tide” is the traditional approach and involves combining flood defences, flood storage - where land is designated to flood relatively frequently - and occasional large-scale planned flooding for rare events.
“Adapting to the tide” could see land use changed in some areas, with defences moved back to create larger areas for water to be held and, if it is no longer possible, discontinuing the management of some flood defences.