Natural Flood Management (opens new window) should be the primary tool in tackling flood risk. Interventions in the Peak District can both hold water and release it slowly, reducing flood risk downstream during storm and heavy rainfall events, as well as creating wet habitats that are good for wildlife.

By tackling the problem of flooding at the entire river (opens new window) catchment scale (opens new window), Natural Flood Management has the potential to improve flood resilience: slowing the flow of water (opens new window) more effectively at reduced costs compared to the exclusive use of traditional engineering approaches.

Slow the Flow © - https://slowtheflow.net/

Opting for greener, "spongy (opens new window)" approaches to tackle flooding, by slowing and absorbing water is well suited to areas like the Peak District. Increasing the amount of water stored using natural features, with vegetation to slow the flow of water can reduce the flood risk, lower maintenance costs and benefit nature in the Peak District. Slowing the flow in the Peak District is likely to have huge benefits to surrounding towns and cities such as Sheffield, Derby and Chesterfield (opens new window) in reducing downstream flood risk.

For nature

• Making water channels more complex results in a range of chutes, pools, submerged and exposed sediment bars, creating micro-habitats for a range of plants and animals.
• Creating wet woodland to add to the 117 hectares recorded in the Peak District will help the rare willow tit.
• Woody debris scours the river or stream bed, cleaning and sorting spawning gravels for fish such as trout and salmon. Tree roots and woody debris in watercourses slow the flow, shade the water and provide protection from predators, making them ideal nursery sites for young fish.
• Increasing surface area for algae and microbes which form the base of the food chain helps species such as the Southern Iron Blue Mayfly, a priority species and indicator of healthy rivers found in the Peak District, which feed by scraping algae from underwater objects, or by gathering organic material from the sediment.
• Exposed riverbanks and sand and shingle patches along rivers act as microhabitats for insects and nest sites for kingfishers and sand martins.

What else can natural flood management deliver?

• A mosaic of habitats for different species.
• Woody debris and trees can increase resilience to climate change by regulating temperature and water levels, as well as providing a long-term carbon store.
• Reconnecting rivers to their floodplains can reduce diffuse pollution by accumulating silt on the floodplain.
• Large woody debris helps trap and retain sediment, organic matter and coarse woody debris such as twigs and leaf litter, preventing it being washed away downstream.
• Increasing water holding capacity and slowing the flow may reduce the need for costly engineering and hard infrastructure.
• Woody debris can protect banks from erosion by resisting and deflecting flow, and trees help stabilise soils in and around the banks.
• Willow is rich in cobalt, which when grazed, can make up the deficiency in grasses in late summer, providing natural immunity (opens new window) to disease and reducing worm burden (opens new window).
• Re-wiggling watercourses will increase their length and potential water-holding capacity, and slow down the water flowing through, both of which will improve flood resistance further downstream.
• Natural flood defences such as ponds, wetlands and vegetation may have reduced maintenance costs compared to engineering and hard infrastructure.
• Natural Flood Management can create more aesthetically pleasing flood defences compared to concrete or metal drains and tunnels, increasing people’s enjoyment of using these areas.
• Options for delivering natural flood management could attract private finance to support costs.

In practice

• Starting at the top of the catchment, restoring blanket bog holds water and slows the flow.
• Leave naturally fallen woody debris, or install trees and/or branches. Coppice or pollard riverside trees can be tied using plastic-free twine, or naturally hinged. If there is a strong flow, pin to the bank or riverbed using untreated wooden posts, wire or cable, link chains and/or rebars. Seek advice from the Environment Agency or lead local flood authority to check if you need consent to install woody debris.
• Help water courses become more natural by re-meandering and increasing the variation in width. Remove culverts and drains where possible.
• Restore hydrological connectivity between watercourses and flood plains, by allowing geomorphological processes such as natural bank erosion or removing flood bunds. This can also involve larger scale reconnections, restoring multiple channels and wet grassland.
• Plant or allow natural regeneration of trees and scrub along watercourses.
• Create ponds and wet areas as water storage.
• Leave or create exposed sand and shingle patches and banks along watercourses.
• Maintenance payments for delivering natural flood management options should be highest, prioritised and fair, considering the public goods that could potentially be delivered.
• Ensure any work conducted is done so with the correct permits (opens new window), and is within the Environment Agency`s guidelines.
• The reintroduction of beavers could be an appropriate and feasible means of contributing to natural flood management in some relevant places, in consultation with local communities.

CASE STUDY Re-wiggling and woody debris at High Ash Farm