Water Framework Directive: Characterisation Of Reference Conditions And Testing Of Typology Of Rivers

Final Report - ERTDI Report 31 - Kelly-Quinn et al

Summary: A survey of 50 sites previously classified as high quality by the EPA, to determine whether they were of high ecological status (and thus could be used as reference conditions) and to use these spatial reference sites to develop the river typology for the Water Framework Directive.

Published: 2005

ISBN: 1-84095-162-1

Pages: 21

Filesize: 1,032KB

Format: pdf

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Executive Summary

To fulfil the obligations of the Water Framework Directive, a river typology within Ecoregion 17 had to be produced. The objective of this study was to survey 50 sites within Ireland that had been previously classified as high quality by the Environmental Protection Agency, to determine whether they were of high ecological status (and thus could be used as reference conditions) and to use these spatial reference sites to develop the river typology.

The biological elements (macroinvertebrates, phytobenthos and macrophytes) were surveyed at all 50 sites during 2002/2003. Chemistry (ammonia, phosphate, nitrate, nitrite, hardness, alkalinity, dissolved oxygen, pH, temperature, calcium, magnesium, potassium, chloride and sulphate) and basic hydromorphological variables (sediment, bank slope, etc.) were measured during the same period to ensure reference status.

Q-values, TDI and MTR scores were applied to the biological elements to judge reference status, although it was acknowledged that these methods may not be appropriate since different river types cannot be directly compared using these measures. Potential deviations from reference status were identified by the biological elements, chemistry and hydromorphology at 23 sites, although coincidence of impact indication from the different elements only occurred at six sites.

Agreement of a biological response with chemistry only occurred at one site (MOY2). Despite potential minor impacts, it was considered that the development of the typology would suffer more from the omission of river types than from the effect of the potential impacts.

Thus, no sites were excluded, though the status of MOY2 and OGLIN1 should be reviewed in future developments. Several typologies were developed from this dataset: Expert based, Canonical Correspondence Analysis (CCA) based, the WFD System A Typology, and typologies developed from permutations of different environmental variables and variable boundaries.

The permutation-based typologies best segregated the biological elements across all groups, and with combined biological data. A 12-category permutation-based typology was recommended as the best typology, and has now been accepted by the EPA.

Categorisation of the 50 sites, indicator species, and the frequency of different species are shown for the 12 different river types within this typology.