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The Biological General Quality Assessment (GQA) was developed in 1995 to report the national biological quality of rivers in England and Wales. It is based on the comparison of observed data with the RIVPACS Predicted Ecological Quality Index (EQI), providing insights into the distribution of EQI values. This classification system utilizes EQI_ASPT and EQI_N-Taxa to derive the Biological GQA and includes classifications, definitions, and confidence measures for grade changes.
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BIOLOGICAL GQA National Classification for reporting Biological Quality in England and Wales
Biology GQA • Biological General Quality Assessment • Developed in 1995 to report National Biological Quality of Rivers in England and Wales • Based upon comparison of Observed data with RIVPACS Predicted - Ecological Quality Index (EQI)
Observed EQI Predicted Ecological Quality Index (EQI)
Distribution of EQI Values England and Wales 1995
Biological GQA Classification Class limits
Derivation of Biological GQA using EQI_ASPT & EQI_N-Taxa
Biological GQA Class definitions
Confidence of Grade & of Grade Change
Illustration of Confidence of Change in Grade
Example of use confidence of change
a b c d e f Biological grade probabilitites for the upper Aire, 1995-1998
Biological grade probabilitites for the lower Aire, 1995-1998 a b c d e f