Combating flood risk: The importance of trees and other natural water storage

Date 30.01.2024
Category Advice
Author LJ Stocks

It’s no secret that the UK has been hit by some of the worst flooding in history this winter. With significant storms battering towns and villages, rivers and streams have been overwhelmed and residents evacuated from their properties. 

Earlier in the year, on a single day there were over 80 flood warnings issued in the UK, and with rivers at record levels and flood barriers proving ineffective, there is cause for taking urgent action.

Modern evolution

More than six million homes are at risk of flooding in the UK, and with major investment in protective man-made infrastructure, there has been far less focus on any natural approaches to reducing flooding.

Centuries past would have seen agricultural and rural land holding much of the run off and overspill of rivers, however this landscape has undergone a fair amount of modification to increase agricultural profits and with the built environment evolving and modernising, there are now few places to accommodate this floodwater.

Looking to nature

There is potential for the natural landscape to go some way to solve this issue, with trees and other natural water storage offering great potential for alleviating flooding. The Rivers Trust works with nature to reduce the risk of flooding for communities. During 2022-23, The Rivers Trust installed over 900 natural flood risk management measures across the UK. These included:

  • Leaky dams – placing logs across a watercourse to mimic fallen trees to slow the movement of water.

  • Rain gardens and Sustainable Urban Drainage (SUDs) – reducing run off in urban areas.

  • Woodland creation – planting trees in the right place can help manage flood risk. Leaves intercept falling rain and slows the rate at which it reaches the ground, and tree roots bind together the soil, reducing the amount that washes into watercourses as well as helping water penetrate deeper into the soil at a faster rate.

  • Creating wetlands and storage ponds – reducing the amount of water elsewhere.

The Rivers Trust is committed to help with flood management, and many local flood management projects now exist in high risk areas. 

A focus on trees

The Woodland Trust report that, “Trees reduce surface water run off by 80% compared to asphalt”. Increasing trees in urban areas could have a serious impact on flooding in towns, drastically reducing the run-off of rain in built up areas. Root systems take water into the soil, and canopy cover is estimated to allow 30% of rain to evaporate back into the atmosphere, meaning it never hits the ground at all. 

In rural locations, the removal of hedges and trees has increased run off from fields, adding to the issue of flooding during heavy rainfall. The Woodland Trust work with the Environment Agency and lobby government to ensure that natural flood risk management solutions are considered as part of local and regional flood management solutions.

Restoring wetlands, developing water retention areas and looking to retain and develop woodland and trees in flood-prone and urban areas could all benefit flood management. Long term approaches must include natural solutions, to help communities thrive, without the fear of losing their possessions and homes.