Riverbank Protection at River Derwent, Cumbria, UK

Introduction & Problem Statement

On the River Derwent in Barepot, severe erosion of the right bank resulted in damage to important infrastructure. The access to the pumping station, the bank near the weir and the stability of the weir itself were affected. Targeted protective measures were required to secure the facilities and prevent further damage.

The Challenges

The riverbank showed significant scouring as a result of riverbed scouring. In addition, the river began to dig a new, shorter riverbed across the landscape, bypassing a large weir structure. After a severe flood, the bank had receded by over 6 metres and large scours formed at the base of the bank. This weakened the weak bank areas to such an extent that they were susceptible to further erosion even during minor flood events.

The Solution

As this is an ecologically sensitive location, conventional, hard bank protection was out of the question and biotechnical constructions were favoured.
Large rock fills were not considered either due to negative effects downstream and other ecological impacts. 
The solution for controlling erosion in the scour basins came in the form of AquaRockBag®.

Advantages

AquaRockBag® reduces water flow in a controlled manner by absorbing the energy of the water. In addition, by using smaller stones, AquaRockBag® function like artificial reefs and provide a habitat for flora and fauna. To further support renaturation, tree trunks, rootstocks, and willow stakes were installed as revetments. This allows everything to blend in naturally and ecologically with the surrounding environment.