Resource Metadata

NFM Prioritisation for Small Flood Risk Catchments

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NFM Prioritisation for Small Flood Risk Catchments
Resource ID
3d1e1ac9-50e3-459d-9b63-096bbbe9dbdf
Title
NFM Prioritisation for Small Flood Risk Catchments
Date
Feb. 18, 2025, midnight, Publication Date
Abstract
This dataset comprises of a prioritisation method 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. 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. This dataset comprises of a prioritisation method 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. 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 catchments have been categorised based on the percentage area of NFM potential of: <10% 10%-25% 25%-50% >50%
Edition
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Responsible
natalie.small@gov.wales
Point of Contact
Wells
dickon.wells@gov.wales
Purpose
This dataset was developed to aid in the identification of catchments suitable for Natural Flood Management.
Maintenance Frequency
None
Type
vector
Restrictions
Other Restrictions
This mapping should be reviewed against the following datasets:  Archaeological sites Historic Environment Features (HEF) Historic Landscape Areas (HLA) Registered Historic Parks and Gardens (RHPG) Scheduled Monument (SM) 50m buffer Scheduled Monument World Heritage Site (WHS) Bio-physical  Acid Sensitive Catchment Ancient Woodland Inventory Deep Peat and Modified Deep Peat Grassland Fungi Potential Habitat for Fritillary Butterflies over Bracken Potential Habitat for Great Crested Newts Potential Habitat for Open-ground Dependent Birds Priority Habitat – High Sensitivity Priority Habitat Mosaics – Investigation Required Red Squirrel Areas Regionally Important Geodiversity Site (RIGS) Sensitive Arable Plants Potential Habitat for Water Voles Landscape designations  Area of Outstanding Natural Beauty (AONB) Registered Common Land National Park Open Access Site of Special Scientific Interest (SSSI) Site of Special Scientific Interest (SSSI) 100/300m Buffer Upland Special Protection Areas (SPA) Upland Special Protection Areas (SPA) 500m Buffer Agriculture Agricultural Land Classification
License
Open Government Licence for Public Sector Information
Language
en
Temporal Extent
Start
Jan. 1, 2011, midnight
End
Dec. 31, 2022, midnight
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: Prioritisation Map for Natural Flood Management – Larger Catchments Natural Flood Management Status Report To compliment this mapping, the user can also refer to the following open-source layers, which have not been included in this prioritisation: Agricultural Land Classification Bio-physical sites, archaeological sites and landscape designations as described under “Restrictions”  
Data Quality
The data has been derived from:  Flood Risk Assessment Wales – Flood risk from Surface Water and Small Watercourses OpenPopGrid OS Open Terrain WwNP 1% AEP Runoff Attenuation Features WwNP Floodplain Reconnection WwNP Riparian Planting WwNP Catchment Planting SCCAN Bog Restoration Opportunities SCCAN Surface Roughness Opportunities SCCAN Agricultural Management Opportunities The user should be directed to the Prioritisation Mapping Technical Report for the methodology used to produce this dataset.
Extent
  • x0: 179010.0
  • x1: 353860.03125
  • y0: 166220.0
  • y1: 393770.03125
Spatial Reference System Identifier
EPSG:27700
Keywords
no keywords
Category
Environment
Regions
Global