What is Natural Flood Management?

Flooding is a historic natural phenomenon whereby prolonged heavy rain feeds into rivers and then into lowland waterways which can then become overwhelmed and the water spills out onto the floodplain.

However, flooding is getting worse both in terms of the number and intensity of flood events. Flooding also has a knock on impact on the sewage system which can’t cope with the amount of additional rain water in the system. The primary causes of the increase in flooding are climate change, agricultural intensification, changes in land drainage, increased development, building on flood plains and a reduction in wetlands.

A lot of work has taken place in straightening out rivers, dredging rivers, general tidying and removing of obstacles. Paradoxically the impact has been to deliver water downstream more quickly and therefore increasing the risk of flooding.

Natural flood management aims to reduce the speed of the flow of water to the lowest point by introducing natural features in the landscape. Where these features are located needs careful thought depending upon the exact details of the catchment. The main approaches are slowing water, storing water, increasing water filtration into soils and mitigating the impact of rainfall.

Water can be slowed by putting obstacles in the way such as buffer strips and woodland areas or by trying to reduce large areas of hard or compacted surfaces that cause water to flow more quickly. ‘Leaky dams’ is another approach which allows water to pass but restricts the flow if the volume goes above a certain level. The water may then spill over so you need to ensure this happens at an appropriate location. There is also growing interest in reintroducing beavers for their dam building capabilities.