Modeling of Eutrophic Lake Taking into Account the Data Uncertainty

Complex environmental models are often difficult to analyze and are poorly identifiable due to their nonlinearities and the large number of parameters. In this paper the two components of an integrated series of the models that have been developed to simulate species dynamics in lake’s ecosystem are presented. The uncertainty of the data on natural ecosystem’s condition is taken into account by using fuzzy set of possible interspecies relations with graded membership. This approach has been applied to an aquatic ecosystem shallow-water eutrophic lake. Analysis and comparison of the results showed the important role of bacterial-detrital link in the food chains of water body. Thus the membership function is used to choose among various system development scenarios for which the system dynamics for a long time, in this particular case 4 years, is relatively stable. At the same time with the help of the membership function it is possible to identify the critical water conditions, for example, the water body hypertrophicity.