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 UK, 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 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.
Credit: Ryan Milsom Photography
‘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. WWRT have experience in delivering the following interventions to help restore our natural habitats and reduce the risk of flooding:
- Improving soil health so they have greater capacity to store water.
- Restoring drained or overgrazed peat bogs as natural sponges but many have been and no longer hold water.
- Planting trees and hedges to soak up water and intercept water flowing off the hillside, slowing the speed at which it reaches the river channel and moves downstream. Small planted areas, particularly across steep slopes or alongside streams, can really help to reduce the volume of water reaching the river channel.
- Restoring rivers to their naturally ‘wiggly’ form, meandering across their floodplains. Straightened rivers deliver water very quickly to towns and can increase flood risk. Restoring rivers to their natural course and reconnecting them to their floodplains slows peak flows.
- Creating Sustainable Urban Drainage Systems (SuDS), urban land use changes which mimic natural drainage to reduce the volume of surface runoff in urban areas. They also help to reduce pollution and provide environmental enhancements.
- 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.
