WETLAND HYDROGEOMORPHIC CLASSIFICATION FOR SCOTLAND
WFD66
Novermber 2007

EXECUTIVE SUMMARY
The EU Water Framework Directive (WFD), through its translation into Scots Law by the Water Environment and Water Services (Scotland) Act 2003 (WEWS) introduces a series of new wetland related duties for SEPA, and it has been recognised that an inventory of water body dependent wetlands will be an important first step in meeting these requirements.

The overall objective of the project was to produce an inventory of water body dependent wetlands, based on readily available information, and to detail priorities for future research. Three specific objectives were identified from the outset of the project:
Subsequent steps will enhance the level of detail contained within the inventory. The aim of this project was to deliver the initial phases of the inventory, and to develop a prioritised workplan to support its completion. However, due to limitations in national datasets, it has not been possible to deliver an inventory of Scottish wetlands. The project has produced a hydrogeomorphic classification of potential wetland areas within the Scottish landscape. Using this approach it is possible to construct an inventory of potential wetland sites and to assess their likely surface and groundwater dependence.

A GIS-based wetland hydrogeomorphic classification has been created for Scottish wetlands. The classification provides information on both designated and non-designated sites. Through a GIS it is possible to define the likelihood of dependency of any wetland area on surface and groundwater bodies by assessing likely water sources. Through an interpretation of the surface and groundwater sources it is possible to identify potential pressures on wetlands.

The information generated within the GIS has been validated against digitized National Vegetation Classification (NVC) communities available for 176 SSSIs. The validation process recognizes that NVC communities are not  perfect surrogates for defining wetlands and their water dependence. Correlations (both Spearman’s and Chi-square) yield highly significant results. However, there are subtle relationships within the output data which need to be understood prior to drawing immediate conclusions. A high degree (>80%) of agreement has been achieved for predicting high groundwater dependency. A much lower degree (~50%) of agreement has been achieved for predicting low groundwater dependency. Hydrogeomorphic units derived to describe extensive peatland areas yield the best results for predicting the potential location of wetlands in the Scottish landscape. A variety of different hydrogeomorphic units demonstrate a strong association with wetland NVC communities. Mapping of these hydrogeomorphic units within the GIS generates an initial inventory of areas of high potential to support wetlands and provides information on the ground and surface dependent water bodies.
 
A user’s guide is provided to assist users in investigating the GIS and deriving information on water body dependency and potential pressures.

The hydrogeomorphic classification is not a finished product and should be continually updated and reviewed to improve the ability to generate an accurate inventory of Scottish wetlands. A prioritized workplan is presented to inform future research needs.

Keywords: wetlands, inventory, surface water dependency, groundwater dependency, pressures, Water Framework Directive, GIS, hydrogeomorphic classification

Copies of this report are available from the Foundation, in electronic format on CDRom at 20.00 + VAT or hard copy at 25.00, less 20% to FWR members.

N.B. The report is available for download from the SNIFFER Website.