Assessment of the Geochemical State of Small Rivers Using Fuzzy Set Theory

Abstract

In this paper, for the assessment the geochemical state of small rivers we have solved the problem of identification of a mathematical model of self-purification processes in the rivers with low water consumption. The scheme of statistical testing of the model, allowing to create an adequate model of the object on the basis of available experimental data was developed. Finding areas of acceptable values of the model parameters is carried out during the simulation test, which is based on the Monte Carlo method. Sufficient estimation accuracy of the number of tests is obtained using the Laplace integral theorem. Approbation of the proposed scheme is done on the example of the river Tsna as a receiver of treated wastewater of industrial enterprises of Tambov. As a result of the study, the following processes occurring in the river were identified: aerobic oxidation of organic matter, nitrification, denitrification, plankton growth and death, deaeration of water with air oxygen, protein and urea ammonification, ion exchange and others. At the final stage of the study, an assessment of the geochemical state of water in the studied section of the river was carried out, including forecasts of the content of dissolved oxygen in the water.