Flood gate

The job of getting water to go where you want it to go has just got easier thanks to an invention pioneered by the Environment Agency.

In 2007, Mike Williams, a technical specialist with the agency, teamed up with a Devon-based engineering company to develop a device that could revolutionise the way wetland habitats are created.

The challenge was to come up with a better way of creating wildlife-rich wetlands around rivers and estuaries without increasing the risk of flooding to adjoining land and properties.

Although the technique is widely used in the US, there are only a few sites in the UK and, where it has been used, the equipment has had to be imported – with cost and carbon-footprint implications. Williams believed that the Environment Agency could develop its own design that could be manufactured locally and installed in more places.

After months of development, Williams and a team from Stoneman Engineeringfinally hit upon a solution - a rotary valve. Made of stainless steel and operated by an adjustable float, the valve controls the amount of water flowing in and out of a site.

One of the advantages of the design is that it can be incorporated into existing flood-defence structures and is easily adapted to different locations. Another important advantage is that it is much easier for fish to move freely in and out through the valve. This is a major improvement on conventional valves that can injure fish or stop them gaining access to wetlands or parts of river systems.

A prototype valve was recently installed at Black Hole Marsh near Seaton by the agency and East Devon District Council as part of the Axe Estuary Wetland Project.

The valve remains closed at low tide to stop freshwater entering the tidal lagoon. At mid-tide, it opens to allow salty water to enter, but closes again at high tide to prevent flooding.

As well as estuaries and coastal sites, the device can also be adapted for use on rivers and freshwater wetlands. Williams and his team believe that it could soon be used in habitat creation projects across the country.

‘We’re receiving a steady stream of inquiries. An agency colleague in Nottingham is keen to install one of our valves on the River Trent to allow fish to access new parts of the catchment and we’re working on another tidal site in Hampshire. Other organisations such as the RSPBare also showing keen interest,’ said Williams.

Inspiration for the device came from an unlikely source. Williams was discussing the finer points of regulated tidal exchange with a fellow ecologist and motorcycle enthusiast when he remembered how rotary valves were used in old two-stroke engines. This Eureka moment led to the same engineering concept being employed in a new guise.

‘The device had to meet some pretty tough criteria. It had to be low maintenance, require no power and allow fish movement. It is very satisfying to have come up with such a successful solution that ticks all the boxes and can be so widely applied. Stoneman Engineering has been excellent in providing us with all the design and technical support we needed,’ said Williams.
                                                                                                                          
The agency is taking out a UK patent on the device that cost around £20,000 to research and develop. Once it has become established in the UK, it is thought that the rotary tidal valve could go worldwide. Once it has a patent, the agency can control licensing of the invention.