Harrington's desirability function for natural water quality assessment

The theoretical analysis of the possible application of Harrington's desirability function for the state of natural ecosystems assessment was made. It was shown that the desirability function with double limiting should be used for water quality objects assessment. The function makes it possible to eliminate arbitrary rule while the number of quality classes at different ways of optimization (typification, classification etc.) of information was determined. This resulted in mathematically valid limitation to the maximum 5 types of the first level. It was underlined that if even one particular response or a particular desirability function does not satisfy the requirements, the general estimation should be considered unsatisfactory, in spite of the fact that the other parameters (properties) of the studied system were satisfied. The tables were made which gave the possibility to assess the up-to-date state of the Rybinsk Reservoir ecosystem according to the content of nutrients and organic matters on the basis of future mesurments. The seasonal pattern of hydrophysical, hydrochemical and hydrobiological processes should be taken into account in order to make more accurate the water quality assessment at the concrete time in the definite site in the Rybinsk Reservoir area.