MNV delivers restoration solutions for rivers and river channels, including erosion damage caused by flood flows, rivers which have been damaged by machinery, canalised, culverted or gravel abstraction, inappropriate infrastructure in or next to the river, where effluent discharge affects water quality and where water abstraction or storage impacts the natural flows of the rivers.
The benefits of river restoration include the improvement of aquatic and riparian habitats, removal of barriers to fish migration, protection of properties and infrastructure and the control of flood flows. Where possible the restoration work should work with the river to restore natural processes with developments designed to accommodate the natural flexibility of a river channel.
This type of work can be very sensitive and detailed surveys of the river are undertaken, designs are developed and monitoring systems installed. All aspects of the river system are considered from land ownership, fish migration, protected species and protection of water supplies. The work is carried out at appropriate times of the year and measures undertaken to avoid damage caused by machinery operating in or close to the rivers.
The techniques used by MNV for river restoration work includes:
- Rock armouring – use of boulders as rip-rap in very energetic rivers.
- Root wadding – building root protection into river banks.
- Log terraces – use of tree trunks to protect steep river banks
- Willow spiling – use of green willow to create living bank protection.
- Meander restoration – re-create channel meanders in canalised rivers
- Leaky barriers – creation of leaky barriers along river banks
- Riparian tree planting – restoration of woodlands for bank protection
- Large woody debris – restoration to create natural buffers in the channel
- Sediment management – excavation of excessive sediment accumulations .
During the work the river will be protected so dry working areas are created using coffer dams, sediment mats, silt traps and straw bales used to capture silt, geotextiles used to protect new excavations and refueling of machinery is carried out away from the river.