ENTROPY PRINCIPLES IN THE PREDICTION OF WATER-QUALITY VALUES AT DISCONTINUED MONITORING STATIONS

A new methodology for predicting water quality values at discontinued water quality monitoring stations is proposed. The method is based upo n the Principle of Maximum Entropy (POME) and provides unbiased predic tions of water quality levels at upstream tributaries and on the mains team of a river given observed changes in the distribution of the same water quality parameter at a downstream location. Changes in the valu es of water quality parameters which are known a priori to have occurr ed upstream, but which are not sufficiently large to account for all t he observed change in the same water quality parameter at the downstre am location are able to be incorporated in the method through the intr oduction of a new term in the basic entropy expression. Application of the procedure to water quality monitoring on the Mackenzie River in Q ueensland, Australia indicates the method has considerable potential f or prediction of water quality at discontinued stations. The method al so has potential for identifying the location of causes of observed ch anges in water quality at a downstream station.