A section of riverbank on the Owenkillew River which was eroded by flash flooding in Co Tyrone, has been stabilised as part of a wider habitat enhancement project being progressed by Loughs Agency.
Flood waters had stripped the 160m riverbank area of vegetation, and trees became unstable resulting in subsidence and suspended solids entering the river at Beltrim Estate in Gortin.
Sharon McMahon, Loughs Agency CEO, said: “Managing and supporting a sustainable wild fishery is a careful balance of conservation, protection and letting nature take its course. As part of the Agency’s annual monitoring programme, this site was identified as needing support to improve water quality and maximise the potential of downstream spawning sites. It is one of several river enhancement projects being delivered in the Foyle catchment this year and builds on previous projects all aimed at restoring aquatic habitats to support wild salmonid populations.”
Loughs Agency engaged with the landowner who had recently installed fencing to protect the riverbank from livestock access. The Agency reinforced the bank by driving vertical larch timber poles into the edge of the river and fixing layers of horizontal poles to protect the base of the riverbank. Brash was installed behind the poles to help catch silt and debris and naturalise the bank.
The area behind the revetment was planted with native broadleaf trees including Hazel, Oak and Alder. Willow was also planted tight into the riverbank so that the root structure would help stabilise the bank, further reducing erosion. While the riverbank has naturalised with trees and plants becoming established during the summer, the invasive Himalayan Balsam plant has unfortunately also established itself. The Agency hopes to reduce coverage on this non-native species by removing stems before it goes to seed next year.
Seamus Cullinan, Fishery Inspector at Loughs Agency, explained: “It is important to understand the cause of riverbank erosion and design the most appropriate solution to mitigate against it. This type of green engineering is sustainable and effective at providing long-term stabilisation and benefits for the fishery.”
Loughs Agency has used green engineering solutions in other sites in the Foyle catchment, where persistent water flow and floods are responsible for removing bank material, causing erosion and subsidence. The Owenkillew, Camowen, Glenelly and Finn Rivers are among those scheduled for habitat enhancement projects this year.