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

Welsh Government

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%

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Attributes (22)

Attribute name Label Description
id ID Unique ID for each catchment / ID unigryw ar gyfer pob dalgylch
catcharea Catchment area Catchment area in m2 / Dalgylch mewn m2
brarea Area of opportunity for bog restoration Area in m2 of potential bog restoration opportunities / Arwynebedd mewn m2 o gyfleoedd adfer corsydd posibl
brclarea Area of opportunity for bog restoration on common land Area in m2 of potential bog restoration on common land opportunities / Arwynebedd mewn m2 o adfer corsydd posibl ar dir comin
spsarea Area of opportunity for soil infiltration improvements Area in m2 of potential soil infiltration improvement opportunities / Arwynebedd mewn m2 o gyfleoedd gwella ymdreiddiad pridd posibl
rwarea Area of opportunity for riparian woodland Area in m2 of potential riparian woodland opportunities / Arwynebedd mewn m2 o gyfleoedd coetir torlannol
hrarea Area of opportunity for hedgerows Area in m2 of potential hedgerow opportunities / Arwynebedd mewn m2 o gyfleoedd perthi posibl
hcarea Area of opportunity for habitat change Area in m2 of potential habitat change for surface roughness opportunities / Arwynebedd mewn m2 o newid cynefin posibl ar gyfer cyfleoedd garwedd arwyneb
hiarea Area of opportunity for habitat improvements Area in m2 of potential habitat improvement for surface roughness opportunities / Arwynebedd mewn m2 o welliant cynefinoedd posibl ar gyfer cyfleoedd garwedd arwyneb
wsarea Area of opportunity for winter stubbles Area in m2 of potential for winter stubbles opportunities / Arwynebedd mewn m2 o botensial ar gyfer cyfleoedd sofl gaeaf
froparea Area of opportunity for floodplain reconnection Area in m2 of potential floodplain reconnection opportunities / Ardal mewn m2 o gyfleoedd ailgysylltu gorlifdir posibl
rafarea Area of opportunity for runoff attenuation features Area in m2 of potential runoff attenuation feature opportunities / Arwynebedd mewn m2 o gyfleoedd nodwedd gwanhau dŵr ffo posibl
allnfmarea Sum of all areas of opportunity Sum of the areas in m2 of the potential NFM measures / Swm yr ardaloedd y mesurau NFM posib mewn m2
allnfmper Percentage of catchment area covered by NFM opportunity Percentage of catchment Area covered by potential for NFM measures / Canran y dalgylch a gwmpesir gan botensial ar gyfer mesurau RhLlN
dbl_br_a Doubled area of opportunity for bog restoration Weighted area (doubled) in m2 of potential bog restoration opportunities / Arwynebedd wedi'i bwysoli (dyblu) mewn m2 o gyfleoedd posibl i adfer cors
dbl_brcl_a Doubled area of opportunity for bog restoration on common land Weighted area (doubled) in m2 of potential bog restoration on common land opportunities / Arwynebedd wedi'i bwysoli (dyblu) mewn m2 o waith adfer corsiog posibl ar dir comin
dbl_sps_a Doubled area of opportunity for soil infiltration improvements Weighted area (doubled) in m2 of potential soil infiltration improvement opportunities / Arwynebedd wedi'i bwysoli (dyblu) mewn m2 o gyfleoedd gwella ymdreiddiad pridd posibl
dbl_rw_a Doubled area of opportunity for riparian woodland Weighted area (doubled) in m2 of potential riparian woodland opportunities / Arwynebedd wedi'i bwysoli (dyblu) mewn m2 o gyfleoedd posibl am goetiroedd glannau'r afon
dbl_hr_a Doubled area of opportunity for hedgerows Weighted area (doubled) in m2 of potential hedgerow opportunities / Arwynebedd wedi'i bwysoli (dyblu) mewn m2 o gyfleoedd perthi posibl
w_allnfm_a Sum of all areas of opportunity (including environmental weighting) Sum of the areas in m2 of the potential NFM measures including those of double weighting /Swm yr ardaloedd ym m2 y mesurau RhLlN posibl gan gynnwys y rhai â phwysiad dwbl
w_allnfm_p Percentage of catchment area covered by NFM opportunity (including environmental weighting) Weighted percentage of catchment Area covered by potential for NFM measures / Canran wedi'i phwysoli o'r dalgylch a gwmpesir gan botensial ar gyfer mesurau RhLlN
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Type:
Spatial data
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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Publication date:
Licence:
Open Government Licence for Public Sector Information (OGL)

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Copyright:

None

Keywords:
Natural flood management
Point of contact:
Restrictions
<p>This mapping should be reviewed against the following datasets:&nbsp;</p> <p>Archaeological sites</p> <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> <p>Bio-physical</p> <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 &ndash; High Sensitivity</li> <li>Priority Habitat Mosaics &ndash; 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> <p>Landscape designations</p> <ul> <li>&nbsp;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> <p>Agriculture</p> <ul> <li>Agricultural Land Classification</li> </ul> <p>&nbsp;</p>
Purpose

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

Language
English
Temporal Extent
Jan. 1, 2011, midnight - Dec. 31, 2022, midnight
Data Quality
<p>The data has been derived from:</p> <ul> <li>Flood Risk Assessment Wales &ndash; 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> <p>The user should be directed to the Prioritisation Mapping Technical Report for the methodology used to produce this dataset.</p>
Supplemental Information

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

Spatial Representation Type
Vector data is used to represent geographic data
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