Metadata detail: NFM Prioritisation for Small Flood Risk Catchments with weighting for ecosystem service provision.

Title

NFM Prioritisation for Small Flood Risk Catchments with weighting for ecosystem…

Abstract

This dataset comprises of a prioritisation method, with a weighting towards ecosystem service provision, for identifying small catchments, above communities at risk from frequent surface water and small watercourse flooding where Natural Flood Management (NFM) may be a suitable means of reducing flood risk and may also provide additional environmental benefits. The dataset can be used to support the identification of areas suitable for NFM alongside other analyses undertaken by a suitably qualified person.

The information provided is based on a national scale mapping approach, taking into account largely modelled and open-source data, therefore this mapping should be viewed as indicative rather than specific. Locations identified may have more recent building or land use than available data indicates. It is important to note that land ownership and change to flood risk have not been considered.

The principles behind this prioritisation were inform by current academic understanding of where NFM may be most applicable and has sought to use the latest Natural Environment Research Council (NERC) research. NFM has been shown to work at catchment scales up to 10km2 where the community at risk is immediately downstream. The catchments have been delineated using OpenPopGrid, a grid-based estimation of population density and the Flood Risk Assessment Wales (FRAW) surface water flood map to identify small communities at risk from frequent flooding.

These small catchments above communities at risk from frequent flooding are prioritised based on the percentage area of NFM potential as identified in two mapping sources, the Working with Natural Processes (WwNP) potential area maps and the System Cynorthwyo Cunllunio Adnoddau Naturiol (SCCAN) maps. The potential for the following features was summarised in the prioritisation:

Runoff attenuation features (WwNP)
Floodplain reconnection potential (WwNP)
Riparian Woodland (WwNP)
Infiltration improvements on slowly permeable soils (WwNP)
Hedgerows (SCCAN)
Bog restoration (SCCAN)
Habitat change and improvements for increased surface roughness (SCCAN)
Agricultural management through the retention of winter stubbles (SCCAN)

The following features were given a double weighting for potential ecosystem service provision based on an analysis of the WwNP Evidence Directory:

Riparian Woodland (WwNP)
Infiltration improvements on slowly permeable soils (WwNP)
Hedgerows (SCCAN)
Bog restoration (SCCAN)

The catchments have been categorised based on the percentage area of NFM potential of:

<10%
10%-25%
25%-50%
>50%

Licence

Open Government Licence for Public Sector Information (OGL)

Read more about this licence

Copyright:

None

Publication date

18 February 2025

Type

Spatial data

Keywords

Natural flood management

Category:

Environment

Environmental resources, protection and conservation. Examples: environmental pollution, waste storage and treatment, environmental impact assessment, monitoring environmental risk, nature reserves, landscape

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Regions

Global

Approved

Yes

Published

Yes

Featured

No

Group

Water and Flood Division

Spatial extent

Projection system

EPSG:27700

Extension x0

179010.0

Extension x1

353860.03125

Extension y0

166220.0

Extension y1

393770.03125

Restrictions

This mapping should be reviewed against the following datasets:  Archaeological sites <ul> <li>Historic Environment Features (HEF)</li> <li>Historic Landscape Areas (HLA)</li> <li>Registered Historic Parks and Gardens (RHPG)</li> <li>Scheduled Monument (SM) 50m buffer</li> <li>Scheduled Monument</li> <li>World Heritage Site (WHS)</li> </ul> Bio-physical <ul> <li>Acid Sensitive Catchment</li> <li>Ancient Woodland Inventory</li> <li>Deep Peat and Modified Deep Peat</li> <li>Grassland Fungi</li> <li>Potential Habitat for Fritillary Butterflies over Bracken</li> <li>Potential Habitat for Great Crested Newts</li> <li>Potential Habitat for Open-ground Dependent Birds</li> <li>Priority Habitat – High Sensitivity</li> <li>Priority Habitat Mosaics – Investigation Required</li> <li>Red Squirrel Areas</li> <li>Regionally Important Geodiversity Site (RIGS)</li> <li>Sensitive Arable Plants</li> <li>Potential Habitat for Water Voles</li> </ul> Landscape designations <ul> <li> Area of Outstanding Natural Beauty (AONB)</li> <li>Registered Common Land</li> <li>National Park</li> <li>Open Access</li> <li>Site of Special Scientific Interest (SSSI)</li> <li>Site of Special Scientific Interest (SSSI) 100/300m Buffer</li> <li>Upland Special Protection Areas (SPA)</li> <li>Upland Special Protection Areas (SPA) 500m Buffer</li> </ul> Agriculture <ul> <li>Agricultural Land Classification</li> </ul>

Purpose

This dataset was developed to aid in the identification of catchments suitable for Natural Flood Management.

Temporal extent

Jan. 1, 2011, midnight - Dec. 31, 2022, midnight

Data quality

The data has been derived from: <ul> <li>Flood Risk Assessment Wales – Flood risk from Surface Water and Small Watercourses</li> <li>OpenPopGrid</li> <li>OS Open Terrain</li> <li>WwNP 1% AEP Runoff Attenuation Features</li> <li>WwNP Floodplain Reconnection</li> <li>WwNP Riparian Planting</li> <li>WwNP Catchment Planting</li> <li>SCCAN Bog Restoration Opportunities</li> <li>SCCAN Surface Roughness Opportunities</li> <li>SCCAN Agricultural Management Opportunities</li> </ul> The user should be directed to the Prioritisation Mapping Technical Report for the methodology used to produce this dataset.

Supplemental information

This dataset is one of a suite of products developed as part of the Welsh Government Natural Flood Management Review. 
Other datasets include:<…

Spatial Representation Type

Vector data is used to represent geographic data

Email

floodcoastalrisk@gov.wales

Organisation

Welsh Government

Department

Water and Flood Division

Link online

/layers/geonode:pmfnfm_small_catchments_env_weighting