ABSTRACT
This chapter evaluates the relative merits of existing UK approaches to the chemical assessment of river water quality and explores the potential advantages offered by the use of physicochemical indices of water quality. The utility of physicochemical indices of water quality for detecting changes in water quality has been assessed. Advantages and disadvantages of specific indices to water quality assessment have been highlighted. Rivers are dynamic systems possessing large, temporal and spatial variations in water quality. Long-term trends in water quality are monitored in the UK using the National Water Council Classification. A more precise and rigorous method of utilizing physicochemical water quality data for the detection of both long- and short-term changes in river water quality is provided by the use of Water Quality Indices. The aforementioned indices were developed in four stages: determinant selection, determinant transformations, determinant weighting and determinant aggregation.
