The identification of UK BAP priority rivers:

Generating a spreadsheet of potential, or candidate qualifying river water bodies

(December 2011)


The development of the UK BAP 'rivers' priority habitat

A review of UK BAP priority habitats and species was carried out and published in 2007.  This was the first full review of the UK BAP list, generated over 10 years previously, and its aim was to ensure that the list of priority habitats and species remained focused on the correct priorities for action.  As part of this review, it was proposed that a UK BAP priority 'rivers' habitat was necessary, but that the definition and description of this habitat needed to be developed further.  In particular it was agreed that it was necessary to draw up a set of criteria for identifying features that could qualify a river as a priority habitat, to ensure sufficient coverage of the whole range of river types important for nature conservation, without classifying every river within the UK as a priority habitat.


At the time of the review, the definition of the new priority habitat ‘rivers’ was therefore accepted only in draft form, pending further work and agreement by specialists.  Work to refine the definition and develop the criteria was carried out by a Steering Group, including representatives from the conservation and environment agencies (Scottish Natural Heritage (SNH), Natural England (NE), Northern Ireland Environment Agency (NIEA), Countryside Council for Wales (CCW), Joint Nature Conservation Committee (JNCC), the Environment Agency (EA) and the Scottish Environment Protection Agency (SEPA)), and an NGO (Buglife). 


Agreed criteria

The criteria were finally agreed and published in July 2010, along with a more comprehensive definition of the habitat.  The criteria are summarized as:

  1. Rivers of high hydromorphological status under the EC Water Framework Directive (WFD).
  2. Headwaters.
  3. Occurrence of the EC Habitats Directive Annex I habitat H3260 ‘Water courses of plain to montane levels with the Ranunculion fluitantis and Callitricho-Batrachion vegetation’.  This includes, but is not confined to, all river Special Areas of Conservation (SACs) designated for the feature.
  4. Chalk rivers, as described in the pre-existing BAP definition.
  5. Active shingle rivers.
  6. Areas or Sites of Special Scientific Interest (ASSIs or SSSIs) designated for river species, riverine features or fluvial geomorphology.  This also includes Geological Conservation Review (GCR) and Earth Science Conservation Review (ESCR) sites of importance for fluvial geomorphology.
  7. The presence of priority or indicator species, including: Annex II Habitats Directive species; BAP priority species; and invertebrate species which are strongly indicative of river shingle.


Further information on the criteria is available in the published definition (see
) for the most recent version, updated in December 2011).  For a river water body to qualify as a potential priority river, one or more of the criteria listed is required to be present.


Collecting, compiling and comparing the data

As part of the work to improve the definition and to establish the criteria, a large amount of digital geographic data was collected, including digitized river networks, information on sites protected for riverine features such as A/SSSIs and SACs, habitat classification datasets, and priority species occurrences.  The data were combined and compared using GIS: a base layer of the digitized rivers network of the UK was used, onto which the criteria were mapped.  Priority river stretches could then be selected where qualifying criteria intersect with the base layer.  Only one criterion needs to intersect for a river stretch to qualify.  For example, Figure 1 shows the rivers network in Northern Ireland, overlain by riverine Areas of Special Scientific Interest (ASSIs) the river water bodies which intersect the ASSI layer will therefore qualify for inclusion as potential UK BAP priority habitat. 


Figure 1. The digital rivers network for Northern Ireland (blue) and Riverine ASSSIs (red)

Figure 1. The digital rivers network for Northern Ireland (blue), and Riverine ASSIs (red).


Figure 2 shows two criteria  the EU Habitats Directive Annex I habitat H3260, and chalk rivers  in relation to a trial rivers network for south-east England. Again, priority river water bodies can be identified where one or both of these layers intersect the underlying rivers network.


Figure 2. Ranunculion fluitantis and Callitricho-Batrachion communities (points), chalk rivers (turquoise lines) and a sample rivers network (blue lines) for south-east England

Figure 2. Ranunculion fluitantis and Callitricho-Batrachion communities (points), chalk rivers (turquoise lines) and a sample rivers network (blue lines) for south-east England.


Species data

In order to develop criterion 7, 'the presence of priority or indicator species', a list of species of relevance or importance to rivers was generated. This was extracted from the full list of 1150 UK BAP priority species, which was filtered to idenfity those which rely on rivers. Expert knowledge of species and ecology was used to identify relevant species. In addition, several other species which represent particular riverine environments, but which weren't UK BAP priority species, were considered mostly species which are representative of shingle rivers.


For some species, it was concluded that individual records could be used to select priority river stretches these were defined as 'BAP prioriity species strongly dependent on river habitat quality' (category A species), and 'non-BAP species indicative of shingle rivers' (category C species).  For widespread BAP priority species which are considered to be less dependent on river habitat quality alone (category B species), a threshold of species was felt to be more appropriate.  A threshold of 6 or more category B species was finally agreed by assessing available records and identifying a level which returned an appropriate number of qualifying river stretches.


Further information

It was agreed by the Steering Group that the information gathered in defining and developing the definition and criteria for priority rivers could be of potential use to the wider UK BAP community, in forming a starting point for those wishing to identify priority rivers in their area.  Issues of intellectual property and tight resources do not allow for the publication of the full GIS dataset.  However, it was agreed that a spreadsheet of potential, or candidate, UK BAP priority rivers could be generated, by applying the new definition and criteria to the data collected.  The spreadsheet converts the information gathered into a more useable format, and enables the user to filter or sort the data in a number of ways.


The spreadsheet containing all the relevant data was completed in May 2011, and is now available (December 2011).

In addition, a background document (PDF, 235kb) is available, which provides more detail on the development of the spreadsheet and the data gathered.


Last updated: 13 December 2011