Just a few minutes from Richmond station, the River Thames flows past a parade of royal palaces, stately homes and well-groomed parks. Known as the Arcadian Thames, or London’s countryside, this is where the capital begins to transform into the wilderness beyond it.

But this is a wilderness that has been tamed and controlled over time, much like the rest of the river. To help boats moving along it and to protect riverside communities from flooding, much of the Thames has been straightened and canalised – the natural flood plain either side has been built over and water has been penned in with flood defences.

The dangers of building on flood plains have been exposed more than ever in recent weeks, as a series of storms left hundreds of homes and businesses deluged by water across the UK. The Guardian has revealed that more than 11,000 homes in England will be built on land with a high risk of flooding in the coming years and in some of the areas most affected by the recent floods, up to one in five homes built between 2015-2018 were built in flood zones.

As a result, only 10% of flood plains in England are now fit for purpose, as infrastructure has hindered their ability to store water and act as a natural sponge to soak up deluges.

With the climate crisis set to bring more heavy rains and rising sea levels, the river along the Arcadian stretch in Richmond is just one of many waterways increasingly breaching its restraints and flooding open areas that fall within its natural flood plain.

“It’s pretty much underwater and that is going to be the new norm. The river is telling us that it wants that flood plain back,” says Jason Debney, the coordinator of the Thames Landscape Strategy (TLS), a partnership of 15 organisations and more than 200 community groups leading a multi-million pound project to restore and rewild the Arcadian flood plain.

Volunteers rewild the Home Park water meadows at Hampton Court during a previous project. Photograph: Jason Debney

Despite flood plain land making up 12% of England’s landscape, the Environment Agency says most people have no “general awareness” of of their existence.

“People are so disconnected from their natural flood plains now that they might not understand what we’re trying to do here. They could see it as a loss of open space and the beetle-huggers taking over somewhere where kids can kick a football around,” says Debney. That’s why effective communication and education is an integral part of the rewilding project, which was launched by Sir David Attenborough last year. If the flood plain is not made more effective soon, these areas will end up underwater anyway, Debney says, so it is crucial to develop them now so they can host water and people simultaneously.

Historically the Thames has been controlled by building flood defences such as the Thames Barrier, often in response to specific events such as the 1953 North Sea flood that claimed hundreds of lives. But a report says London has become the most vulnerable city in western Europe to floods as a result of climate breakdown, meaning this method is no longer sustainable, unless residents are happy to see huge walls built along their riverbanks. Debney says: “You can either have that flood defence and be completely disconnected from the river, or you can have a rewilding process, and keep the character of the river.” Healthy flood plains also bring other benefits, as they are a natural habitat for many species and act as a carbon sink.

While a huge flood plain areawould need to be created to completely solve the problem of the rising Thames, Debney says this is an effective first step in stemming the tide. The Arcadia area is at particular risk of flooding as it is the meeting point for seawater flowing upstream and fresh water coming downstream. Changing weather patterns and rising sea levels are increasing the risk of tidal surges, while the paving over of green spaces and increased frequency of heavy storms is directing rainwater straight into the river and increasing flow by as much as 40%.

In Richmond’s Old Deer Park, one of six sites chosen for the rewilding project, an expanse of grass is regularly flooded, rendering it unusable. Debney says the plan would transform this barren area into “one of the most diverse, wet ecosystems anywhere in the country”. The TLS plans to create a network of creeks, wetlands, bogs, reedbeds and fen, a mosaic of wet habitats that could sustain more wildlife and better hold excess river water, with a raised footpath giving public access. Other sites include Desborough Island in Surrey and the Canbury Gardens urban park in Kingston upon Thames.

The London charity Thames21 also works to rewild the capital’s waterways. It says 30km (18 miles) has already been rewilded, but there is scope for at least three times this amount to be restored if the practice is embedded in future planning.

The building of pathways allows members of the public to continue using rewilded areas. Photograph: Jason Debney

Flood plain rewilding projects have long been present in rural areas to try to combat flood risks. In Leicestershire, the Wildlife Trust is working to restore the plains along the River Soar used as agricultural land. “Rewilding helps the flood plain to keep water for longer and makes a big difference downstream in Leicester, where we’ve seen lots of flash floods recently,” says Ben Devine, a conservation officer at Leicestershire and Rutland Wildlife Trust.

“The conventional understanding of flood defences is of a big wall, but we know that collectively these natural flood management [rewilding] interventions work and now we’re scientifically trying to prove it so they can become part of a broader flood management approach,” he added.

Their work involves preventing any more building on the plain, reconnecting wetland habitats and allowing areas to become wilder. Similar work is being carried out on the Upper Aire to tackle flooding in Leeds, which has been hit by the recent storms.

An Environment Agency spokesperson said the need for strong flood plains is more vital than ever: “ Global overheating is changing our weather and increasing our risks of flooding. Over 5 million people in England are at risk from flooding and coastal erosion, yet only a third of people who live in areas at risk of flooding believe their property is at risk.”

Debney warns the Arcadian Thames can breach its banks and overwhelm those nearby in a matter of minutes – a lifeboat is frequently called out to rescue walkers trapped on flooded benches. “Doing nothing is not an option any more. We have to respond in some way. And this is about adapting to climate change.”