Creation of largest-ever flood defences provides new habitats

A now historical shot of Steart Marshes from the air, just before the seawall was breached to create the new flood defences and habitat. Photo: WWT.
A now historical shot of Steart Marshes from the air, just before the seawall was breached to create the new flood defences and habitat. Photo: WWT.
The Wildfowl and Wetlands Trust (WWT) has announced the completion of the UK’s biggest ever coastal realignment scheme at Steart peninsula, Somerset.

Homes and businesses along the Severn Estuary will have a safer future from today (8 September), when the scheme is officially completed. The Steart Marshes WWT scheme – a joint project between the WWT and Environment Agency (EA) – uses the shallow gradient and coarse vegetation of saltmarsh to naturally absorb wave energy. This will help protect local villages from storm surges, and prevent seawalls from eroding so that they last longer. The announcement comes a year after the previous largest coastal relignment scheme was announced by the RSPB at Medmerry, West Sussex.

WWT Chief Executive Martin Spray said: “We need to be bold if we are going to deal with the impacts of climate change. Steart Marshes proves you can protect homes and businesses by using wetland technology that works with nature, not against it. Climate change is here now. Last winter was the wettest on record and we suffered the worst storms for 20 years. I want to give full credit to the villagers of the Somerset peninsula for getting behind this idea, helping to shape it and helping to save the peninsula from being lost to rising sea levels.”
The construction of Steart Marshes means the EA can continue its maintenance of flood risk schemes elsewhere in the Severn Estuary – these already protect 100,000 homes and businesses. People and property remain protected by newly constructed flood risk management scheme, and over the coming months and years salt-tolerant plants will colonise the area and form new saltmarsh.

Rising sea levels are predicted to result in loss of inter-tidal habitat in the Severn Estuary. Steart Marshes will replace about half of this loss and reduce the flood risk for local communities. Just before 7 am on Monday 8 September, high tides entered 250 ha of low-lying land for the first time in centuries, through a newly excavated 200 m gap in the Parrett Estuary coastal embankments.

The scheme uses the shallow gradient and coarse vegetation of the saltmarsh to absorb wave energy naturally. This will help to protect local villages from storm surges, and protect the newly constructed flood banks from erosion so that they last longer.

Richard Cox, for the Environment Agency, said: “Over 200 km of coastal banks around the Severn Estuary reduce flood risk to more than 100,000 homes and businesses, a benefit valued at £5 billion.
Saltmarsh is natural flood risk management. Like coral reefs or mangroves in the tropics, saltmarsh takes energy out of the tide and reduces wave height. At Steart Marshes, the new flood embankments are set behind hundreds of metres of saltmarsh which will reduce the impact of high tides on them, bringing down maintenance costs and prolonging their life.”

Half a million cubic metres of soil were dug and moved to create new and improved flood banks. 
The area is being managed as farmland and a nature reserve, and in time the creek system should become a nursery for commercial fish stocks such as sea bass. Steart Marshes has been carefully landscaped over the last two years and paths and bridleways have been created and improved to help more people enjoy the landscape. Local residents have played a key part in creating the scheme, and several even took part in a sweep of the land, to move any mammals or reptiles before the seawater flowed in.

As well as protecting the country from coastal flooding, and filtering pollution that would otherwise flow into the sea, the Severn Estuary saltmarshes alone support more than 70,000 waterbird