Past human intervention into the course of some rivers has had a big impact on the current state of many of Britain’s waterways.
Straightening, making channels, changing the rivers’ naturaldirection, creating steep banks – all manner of methods over hundreds of years have left many rivers unable to follow their natural meandering course. This has led to waterways getting silted up, unable to release water slowly into the land adjacent. Where once the river would have deposited excess water gently into marshes, now steep banks and unnatural direction of travel means the rivers have to be dredged by machine.
The dredged silt is then deposited on the side of the river, creating even steeper banks and raising the river within the landscape.
The result is water whisking downstream as if in a chute, eventually causing flooding. Habitat is habitually destroyed in the dredging process as there is a loss of much vegetation. In turn, this means species such as eel and crayfish have less to feed on. This has a knock on effect further up the food chain as herons and bittern and other bird species just don’t have a sufficient food source.
One farm cluster that is seeking to change all this is the Breckland Farmers Wildlife Network (BFWN), which is looking to recreate the ‘wiggle’ in one of its rivers. The Little Ouse currently runs through the Breckland area of Norfolk and Suffolk and over the centuries it has been modified to the point where it is running higher than the land around it.
Sam Hurst, a farm adviser for the Norfolk Rivers Trust is working with BFWN to ‘re-wiggle’ the Little Ouse, along with several other rivers, to reconnect them with their natural floodplains. One way to do that, says Hurst, is to dam the river, lower its banks, and see where it went.
If the river were able to find its own way through the valley, breaking its banks in heavy rains, it wouldn’t only create habitats for wildlife, it would also improve the water quality. Currently, the river is overloaded with nitrates and phosphates washed from the fields they were intended to fertilise.
This superabundance of nutrients stimulates the growth of algae, which use up so much of the oxygen in the water that there is little left over for anything else. ‘That really stresses the fish and the wildlife,’ says Hurst. If the river periodically bursts its banks, then the plants and soil on the floodplain will absorb some of the excess nutrients and clean the water.
An additional benefit for slowing the speed of the river would be the restoration of the regions aquifers. The recent years of summer drought have put pressure on water sources in the Brecks but, by allowing the water to recharge the aquifers for longer, then the effects of drought could be lessened.
As well as rewiggling 34 miles of riverbanks along the Black Bourn, Lark, Thet, Wissey and Little Ouse, the BFWN also intend to create a network of heaths, meadows and field margins for species to move through. This is all part of the farmer’s group’s inclusion as one of the government’s Landscape Recovery Pilot schemes.