Engineered Log Jam Features
Bowmont Valley, Scottish Borders
This project represents a catchment-scale approach to managing flood risk by recreating and mimicing natural processes within the river system.
Cheviot Futures has already been instrumental in introducing the concept of Engineered LogJam (ELJ) works to the Bowmont Valley, through the variations on bank protection logjam works already completed at Clifton-on-Bowmont.
Further to this, we now have a series of works completed, introducing a range of ELJ features throughout the valley.
'Bar Apex' LogJams:
These features mimic the action of a fallen tree within the floodplain, acting to slow down flood flows, trap debris and encourage sediment deposition.
This will assist flood management by reducing the debris load, reducing the velocity of flood waters to reduce erosion risk downstream, and also reduce sediment loads.
In total, 45 structures were built throughout the valley, across three sites - Clifton (mid catchment), Swindon Haugh (upper catchment), and Kelsocleugh (headwaters).
Of these, one was lost during the September 2012 flood event, with a further three damaged.
'Grade Control' LogJams:
This feature is intended to assist the repair of a section of incised channel within the headwaters of the Bowmont, on the Kelsocleugh Burn.
Here, the action of water passing through a piped bridge feature has led to scouring and incisment of the natural channel, degrading the river habitat.
This feature will encourage sediment deposition and natural regeneration of the incised section, inmproving the river habitat.
Bank protection LogJams:
Further variations on the timber based protection approach to riverbank erosion repair at key sites within the Bowmont valley were implemented as part of this project.
At Kelsocleugh, a critical farm access route has been protected by a 80m length of logjam, incorporating vertical and horizontal timbers.
At Swindon Haugh a severe eroded section was protected by a series of three separate logjam sections, to encourage restoration of the river channel at that point.
However, this site did not survive the September 2012 flood event, with all three sections removed by the force of the water, leading us to the conclusion that the revised specification utilised due to on-site difficulties was not suitable for the location.
Works were completed during the 2012 riverworks season, between June and August.
Please find below documents relating to the project.