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Flooding is a natural process but climatic changes and the way we manage our landscapes are causing it to become more frequent with increasing devastation to homes, communities and infrastructure. It is predicted that in the U.K. total rainfall will increase in winter with individual storm events becoming more intense. We need to adapt to better manage flood risk; what we have done in the past is unlikely to be sufficient in the future.

Many factors have contribute to increased flood risk in towns and villages. Across large areas soils are compacted and have lost their capacity to store water. Wetlands have been drained and smooth grass fields with few trees allow water to flow quickly into river channels. In many places rivers have been straightened and dredged to move water quickly downstream towards towns and villages. When this huge volume of water reaches a town and is squeezed through walled channels and under bridges it spills out onto its floodplain. Building and development on floodplains leaves the water nowhere to go and so it floods property. We need to slow the speed of water coming off the hills and store more water on natural floodplains.

‘Natural flood management’ is the alteration or restoration of landscapes to store water or ‘slow the flow’ of water reaching the river channel.

Natural flood management techniques are cost-effective, sustainable and deliver lots of other benefits such as cleaning water, storing carbon and increasing wildlife.

See how we can manage our catchments to help reduce the risk of flooding:

So what do we actually do for ‘natural flood management’?

Restoring our natural habitats

• We need to improve soils so they have greater capacity to store water. Soils can become compacted from heavy machinery and livestock trampling. Aerating the soil and maintaining the amount of organic matter in the soil will reduce compaction and improve the soil structure. This will increase productivity and reduce flood risk so it is a win-win!
• Peat bogs are natural sponges but many have been drained or overgrazed and no longer hold water. Restoring peat bogs by rewetting them will allow new layers of moss and peat to form and hold flood water. Find out how Cumbria Wildlife Trust are restoring peat bogs.
• Trees  soak up lots of water and act as a store. They also intercept water flowing off the hillside slowing the speed at which it reaches the river channel and moves downstream. We know it is not realistic to plant up all of our catchments but small areas of planting of trees or hedges, particularly across steep slopes or alongside streams can really help to reduce the volume of water reaching the river channel.
• Short rotation willow can be planted as a crop that is harvested every 3-4 years so landowners can make a profit. It has many of the same benefits as traditional woodland planting for slowing the flow and is a useful foraging habitat for birds. Find out more from Iggesund who work with farmers to grow willow to provide biofuel for their Workington Mill.
• Rivers are naturally ‘wiggly’, meandering across their floodplains. Straightened rivers deliver water very quickly to towns and the energy of all this water moves gravels rapidly downstream. Restoring rivers to their natural course and reconnecting them to their floodplains allows flooding and gravel deposition in areas where it won’t cause damage.

Green engineering

We can also use natural materials to engineer structures within the landscape that store flood water and slow the flow.

For example, building bunds and ponds with extra capacity can allow water to be stored during flood events then drain away slowly. Leaky dams across water courses or pathways of runoff can slow the flow downstream.

The video below shows examples of these different techniques.

Research and modelling

Lots of research into the benefits and effectiveness of natural flood management techniques is underway across the country. The Environment Agency has published a detailed guide to the current state of scientific understanding on natural flood management.

Projects

We are currently delivering and developing a number of Natural Flood Management Projects. Click the links below to find out more:

• Dovenby natural flood management project
• River Annas catchment project
• Flimby natural flood management project
• Cocker catchment project
• Glenderamackin catchment project

Natural Flood Management Handbook

As part of the Cumbria Strategic Flood Partnership we have developed a  guide to different Natural Flood Management measures and how they can fit into a farm business.