NATURE RECOVERY – THE WHOLE RIVER
Restoring the river’s meanders
There are several projects around the country looking at ‘restoring’ streams and rivers to their ‘natural state’:
“Making Swindale Beck meander, pool and ripple once more through the remote Lakeland valley south of Penrith, was part of a project to restore about 60 miles (100km) of streams and rivers in Cumbria to as close to their natural state as possible.”
The question is whether similar things can be done to the River Sid.
It is understood that with urbanisation and flood defences along the stretch of the river within the built-up area of Sidmouth, it is not possible to reconnect the Sid with its flood plain in the lower reaches. There are issues, however, with the decades if not centuries-old engineering leading to the river cutting a deep channel for much of its lower course.
Nevertheless, the river above Fortescue has the scope to meander and wander, creating a diversity of habitats – which would also help to reduce the energy in the system.
The report commissioned by the Sid Valley Biodiversity Group in April 2021 suggests several remedial measures which could be taken:
With the current course, from Sidbury to the sea, having an approximate gradient of 1 in 100 re-meandering could reduce this by approximately 7% but the measures to establish this will also increase hydraulic roughness, further decreasing discharge (Chart 1). As such, allowing lateral erosion will have a net benefit to flow reduction, habitat value and slowing the bed erosion.
• Improve sinuosity on the entire reach wherever there is space to do so.
• Manipulate boulder weirs to move flows laterally. This could be in conjunction with deliberate lateral erosion to produce meanders.
• Add LWM to increase channel diversity and increase hydraulic roughness.
• An environmental Permit from the Environment Agency will be necessary to complete such work.