Floodplain restoration
While natural flood management measures associated with land management seek to reduce flood water generation, natural flood management measures in the river channel or on its bank or floodplain seek to improve the ability of rivers to manage those floodwaters.
Scottish Environment Protection Agency (SEPA), Natural Flood Management Handbook, 2016
Restoring the connection between a river and its floodplain provides a valuable contribution to natural flood management, allowing floodwater to spill naturally onto land to provide significant flood storage, reducing risk to lives and property further downstream. The mid and lower parts of the river system, where the river enters the flatter floodplain, are the most appropriate areas.
Restoration always needs to be carefully planned by specialist water engineers and ecologists as it will influence the behaviour of the flow of floodwater over a wide area. It will need detailed computer modelling and design, and will require planning and other permissions and consents. It is likely to be high cost and need specialist contractors.
Initial advice as to a site’s suitability can be given by local Rivers Trusts (RT), Environment Agency (EA) or Yorkshire Dales National Park Authority staff, and early contact is highly recommended.
River and floodplain restoration encompasses a range of different techniques which are often used in conjunction. They include restoring meanders and removal or setting back of flood banks, often together with habitat creation such as wetlands, habitat for breeding and wintering waders, and wet woodland.
The following flood management measures are classified as level 3. This means that they involve a level of design that is targeted to certain locations within the catchment, requiring planning permission and consents from authorities, and, in most cases, involving professional water management consultant advice. These measures are usually high cost and need contractors to install them.
Restoring meanders
In the past, rivers have been managed to increase the land available for agriculture (by straightening the channel) and to protect land from flooding (by building embankments). Even small becks have often been altered. These changes combine to disconnect rivers from their natural floodplain. Reducing the area naturally available to store floodwater means that the speed and volume of the flood arriving downstream is increased, often affecting villages and towns.
Scottish Environment Protection Agency (SEPA), Natural Flood Management Handbook, 2016
Benefits, methods and considerations
Reconnecting the river with its floodplain
This is work to directly reconnect the river with its floodplain using a wide range of techniques. Choice of technique is dependent upon the type and characteristics of the water body in which it is going to be applied.
These include:
- River restoration
- Reconnecting old side channels
- Breaching of existing earth bunds
- Improving the operation of flap valves within embankments
- Lowering of flood defences
- Connecting the river to floodplain wetland
- Removing or modifying pumping stations
- Breaching embankments as part of habitat creation projects.
