Water Framework Directive Marine Plants Task Team Tools Paper ...

The final metric system works on a sliding scale, as with the full species list, to enable
an accurate EQR value to be calculated for each of the different parameters, an
average of these values is then used to establish the final classification status. For the
calculation of the EQR value for each of the parameters this requires two slightly
different calculations.
For species richness, proportion of red species and the ESG ratio, all of which
increase in value with increasing EQR, use the following equation:
Class Range = CR Class Width = CW
EQR Band Range = BR EQR Band width = BW
EQR = {(value – lower CR)/(CW) x EQR BW} + lower EQR BR
For the proportion of green species, proportion of opportunist species and shore
description, all of which decrease in value with increasing EQR, use the following
equation:
Class Range = CR Class Width = CW
EQR Band Range = BR EQR Band width = BW
EQR = Upper EQR BR ­ {(value – lower CR)/(CW) x EQR BW}