Upper Worfe River Restoration
Severn Trent Water
Atkins, Environment Agency, Severn River Trust, JN Bentley, Mott MacDonald
- Installation of large wood features (e.g. log jams and deflectors) with chestnut stakes to ensure the orientation of deflectors doesn’t shift under high flows.
- Creation of low-level marginal berms composed of compacted earth or gravel. Larger sediment to be placed at the toe of the berm to provide protection against erosion.
- Construction of riffles and glides to raise the river bed and to contribute to shallow, faster flowing sections.
- Designing pools and backwaters to provide variation in bed profiles and resting areas for fish.
- Materials were locally sourced to reduce the cost and carbon footprint during construction.
- Smaller branches and limbs were removed from large wood to allow more efficient flow through and around the feature.
- Pools were created by lowering the existing beds through excavation. A range of water depths was considered when building pools to stimulate the settlement of a diverse range of vegetation.
- Ensuring the backwater entrance were wide enough to allow fish and other fauna to access.
- Hydromorphological features increased the habitat complexity through narrowing, deepening and energizing flows. Furthermore, they locally increased flow velocities to provide cleaner gravel, thus, improving spawning habitats for salmonids.
- Large wood features enabled the kick-start of natural processes, such as scour and preferential erosion/deposition of sediment, resulting in a more sinuous flow path. In addition, such features increased the retention of organic matter (e.g. leaf litter) that in turn improves nutrient processing and supplies a food source for invertebrates.
- The installation of log jams provides cover for fish species and attachment sites for invertebrates.
- We improved bankside conditions for peripheral wetland plant species by laying berms along the river bank.