Probabilistic assessment of water quality by total hardness using gamma distribution

The nature of the total water hardness distribution in the river has been studied. It was found that during the year, changes in the total hardness largely depend on the seasonal factor, therefore, an analysis of the indicator distribution separately for each month was also made. Empirical distribution functions of the total hardness were found from the built-in variational series. It was found that the obtained distribution laws of the water total hardness differ from the normal and lognormal distributions, but are described quite accurately by the gamma distribution. The put forward hypotheses about the laws of distributions were tested by Kolmogorov’s goodness-of-fit test and confirmed. The distribution functions of the water total hardness describe the probabilities of occurrence of events in which the indicator will exceed or not exceed the specified values.