`Assessing the biological quality of fresh waters: RIVPACS and other techniques', edited by John F. Wright, David W. Sutcliffe and Mike T. Furse.
`Assessing the biological quality of fresh waters: RIVPACS and other techniques', edited by John F. Wright, David W. Sutcliffe and Mike T. Furse. Published by the Freshwater Biological Association, Ambleside, June 2000. ISBN 0 900386 62 2. 400 pages. Price £40 softback, £60 hardback (including p. & p.).

RIVPACS - How RIVPACS Works

When a fully validated RIVPACS type predictive model has been developed for a region or country, it can then be used to assess the ecological status of new running water sites of unknown quality.

a rivpacs predictive model

At these new test sites a biological sample is collected and the relevant physicochemical variables measured using the same standard protocols as were used for the reference sites. The RIVPACS predictive model then generates an Expected Fauna from the measured environmental variables. Biotic indices are calculated from this list of expected taxa.

The biological sample taken at the test site provides an Observed Fauna from which biotic indices are also calculated. The Expected and Observed values for various biotic indices are then compared using Environmental Quality Indices (EQI). These are values derived from the ratio of Observed:Expected. The higher the EQI value the closer the observed fauna matches that expected at the site in the absence of any environmental stress.

The RIVPACS type model will provide an output consisting of observed and expected faunal lists (perhaps with expected abundances), observed and expected biotic index values and associated EQI values. The EQI values can be banded into quality classes to aid interpretation of the data across the entire region or country.

It is important to understand that there is just one single classification of the reference sites which is then used in all subsequent predictions. This is based on the best available data for each site. In the UK this is considered to be the overall fauna obtained from combining spring, summer and autumn samples from a site. Using this single site classification gives the prediction system consistency.