Ecological Systems and Devices Annotation << Back On one Approach to Assessing the Quality of Natural Water Bodies Purification Akhobadze G.N. An approach to assessing the quality of natural water bodies purifi cation degree by experts – ecologists using entropy concordance coeffi cient is proposed. A brief overview of modern methods and means of natural water bodies purifi cation from various pollution is given. The necessity of quantitative assessment of the degree of agreement of experts – ecologists ranking the considered natural water body using the coeffi cient of agreement is substantiated. Various calculation options are presented with different numbers of experts and reservoirs, showing the consistency of expert opinions depending on the ranks and object. A functional diagram and algorithm for an autonomous expert opinion analysis device are presented for solving such tasks. Keywords: reservoir, degree of purification, concordance coefficient, information entropy, methodology, expert – ecologist. DOI: 10.25791/esip.3.2026.1581 Pp. 36-42.