A series of berms have been installed along a section of the River Slea, Sleaford, to create in-channel habitat and sinuosity within the river. These berms consist of brushwood faggots (or fascines), chestnut posts and coir matting to introduce some more natural features into the channel.
As this section is confined by hard concrete banks, the river isn't able to erode and deposit material to create meanders across the floodplain as it would in a natural environment. As an alternative for this urban setting, these in-channel berms can be installed to create some natural variation within the channel without moving onto the floodplain.
These berms are set at summer water levels, designed to narrow the channel in low flows and be drowned out in high flows. Their placement is working with the natural process of the river, installed in areas the river has already started depositing material.
Construction of in-channel berms along the River Slea
Berm creation along the River Slea
By narrowing the river and creating variation within the channel these structures provide habitat for different in-channel species which prefer faster and slower moving sections. These species at the bottom of the food chain are essential to supporting our larger animals throughout the blue green corridor.
The pre-planted coir matting that has been secured into the structure to introduce aquatic and marginal habitat for our local species. Due to the high wild fowl population along the River Slea, bird deterrent has been attached to the berms to prevent the plants being eaten before they have established!
A gravel bar was installed in this section to prevent bankside erosion due to high footfall in the area as well as adding additional habitat to the area.