A sunny September allowed us to start and complete an in-stream berm installation project at Dysart Park in Grantham.
This particular area of The River Witham was a straight channel with little feature. Due to the high number of trees growing on the riverbank, which were also shading the watercourse, we were able to use a technique called tree-hinging for this project. The benefits of tree-hinging is that we can use natural materials that are already abundant within the area, whilst also opening up the canopy to allow light onto the watercourse.
Berms are low level shelves in the water, formed by partially felling and bending tree structures into the water. Leaving part of the trunk attached at the base allows for the tree to be anchored into place. Once the tree has been anchored this creates the front of each berm, which is then subsequently back filled with brash and faggots (bundles of hazel twigs). Each berm is then secured using wooden stakes and wires.
These berms naturally create the ‘wiggle’ back into the watercourse, and in this instance was quite dramatic – given the very straight channel to begin with. The berms naturally provide shelter for fish and other river dwellers and over time will enable natural plants to take hold providing much needed greenery in the future.
By recreating the natural meander that would have once been a feature of the watercourse. This allows pools of deeper, calmer water as well as the shallower riffles that both allow for a more natural river process. Faster flowing water scours and cleans the riverbed, making it a better habitat for spawning fish whilst silt build up during higher flows will develop each berm into a natural part of the watercourse.
The hinging of trees let in a huge amount of light into the watercourse, but also for nearby residents too and the overwhelming positive feedback has been wonderful. As a local company we are very lucky to have this on our doorstep, both from a work and personal perspective.
We were delighted to work alongside Lincolnshire Rivers Trust for this project as part of their Heritage Fund supported by the National Lottery.