What is NFM?

Learn more about the importance of natural flood management and the different measures that can be taken.

A Calderdale field full of trees that have just been planted

Natural flood management (NFM) involves using natural processes to slow the rate of water runoff from the hillside into our valleys.

NFM measures can also increase the volume of water that the landscape can hold to reduce the risk of flooding. This catchment-based approach is an evolving area of work nationally, regionally and locally.

NFM is a key theme in our Flood Action Plan with local organisations playing a key role in developing an evidence base to promote its use on a wider scale. The actions in the Plan are being delivered by a range of partners in collaboration with various landowners to complement engineering works in the borough.

Close up of an empty attenuation basin.
NFM measures

NFM measures can include anything from planting trees to changing the way farmland and moorland is managed so that it absorbs more water. In Calderdale, our work focuses on:

Tree planting

Planting trees helps to prevent flooding by slowing rain reaching the ground, absorbing water as they grow and helping water to infiltrate the ground. They also help stabilise slopes and slow rainwater flowing downhill.

Several large tree planting projects are underway that will see thousands of new trees being planted in Calderdale, including Landscapes for Water and the White Rose Forest.

Treesponsibility has planted an average of 5 hectares of new woodland per year in Calderdale. Hundreds of people from all walks of life have been involved with the project. They include local volunteers and landowners, schools from Calderdale and beyond, a wide range of community groups, and visitors from further afield joining them for their tree planting weekends.

Slowing surface water runoff

Using our unique landscape in innovative ways can help to slow the volume of water coming down our hillsides. Examples of this includes the construction of attenuation basins to store large quantities of water which slowly empty once the rain has passed, and leaky woody dams that mimic natural water management.

Local charity, Slow the Flow Calderdale run regular volunteer days building leaky dams and delivering other NFM measures in the areas that it will have the greatest impact.

Soil aeration

By aerating their land, landowners can help reduce flooding downstream. Aeration of grassland allows greater infiltration, which reduces the amount of water travelling across the surface of a field and beyond. There are other benefits to soil aeration such as allowing air to get to the grass roots and soil, helping root development, alleviating compaction, and reducing slurry and fertiliser runoff.

Panoramic view of Calder Valley. Rolling hills with mist sitting in the valley bottom.
Woodland management

Whilst trees generally protect against erosion, beech trees are different because they shade out the understory and are shallow rooted, which can present an erosion risk on steep valley sides. As a result, selective felling of beech trees is sometimes necessary, allowing the forest floor to revegetate and slow down water passing downhill.

Preserving our moorland

Moorland in good condition is covered in plants that absorb water and slow the flow of water into our valleys.  By improving the health of moorlands, we can help to reduce the risk of flooding in our towns and cities.

Reservoir management

Yorkshire Water is currently evaluating the success of recent trials involving a change in how it manages its reservoirs in the Hebden Bridge catchment to help reduce flood risk in the area.

This trial involved reducing the levels of the reservoirs to allow for the storage of flood water. This will help them to understand whether this is feasible and whether a longer-term change to reservoir management is possible.

Sustainable Drainage Systems (SuDS)

While the above initiatives are going a long way towards improving Calderdale’s flood resilience, there are a number of ways that members of the community can contribute on an individual level. Placing small interventions such as green roofs, permeable paving, leaky water butts, raised planters and attenuation ponds in our homes and gardens could result in a significant amount of water being temporarily stored during storm events in our urban areas. Find out more.

If you are interested in implementing natural flood management on your land, contact nfm@calderdale.gov.uk.

Landowner standing next to a leaky dam made with large sticks.
Natural Flood Management in Calderdale

There are a number of projects across Calderdale designed to naturally manage flood risk. This interactive map shows completed and ongoing Natural Flood Management projects across the Calder catchment, detailing the types of interventions, funding sources and partnerships that have made this work possible.  This spreadsheet summarises all of the information presented in the map.

Open up the map, then press the ‘Present’ arrow and allow the map presentation to fully load which, can take a couple of minutes depending on your internet speed. The orange hexagonal shapes at the top of the map explain how to move around the map and take a look at the project information presented.

Natural Flood Management Opportunities

While lots of work is already underway to naturally manage flood risk, there are a number of sites across the Calder Valley that would benefit from NFM initiatives.

The implementation of NFM measures can vary in terms of complexity, cost, and the benefits provided. This guide provides advice on the range of NFM measures available, the benefits provided and key information for landowners and farmers to consider which measures might be appropriate for their land. Information is also provided on the potential sources of grant funding available to help support the work.

This Natural Flood Management Opportunity map sets out the land areas where new NFM measures are likely to make the greatest impact for flood resilience and where ecological impacts are likely to be low, or where there may be some ecological constraints. The land across Calderdale is colour coded to show potential high-level opportunities based on our current ecological knowledge and catchments which have been prioritised through modelling.

Thinking about implementing NFM on your land? Get in touch for assistance and to hear about any funding opportunities that may be suitable: NFM@Calderdale.gov.uk.

To ensure we protect the biodiversity of Calderdale and don’t create flooding issues elsewhere, there are a number of steps that must be taken before NFM can be undertaken. This document explains these, and aims to assist landowner’s in the implementation of NFM upon their land. The NFM Project Officer is also available to assist landowners with any element of this, get in touch via: NFM@Calderdale.gov.uk.


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