Analysis of Long-Term Changes in Anoxic Zones in the Mozhaisk Reservoir Based on Model Calculations

The results of model calculations of the characteristics of anoxic zones in the Mozhaisk Reservoir over a 57-year period have been analyzed. A two-dimensional box hydrological model of the reservoir has been used to calculate variations of the values of ecological variables with a daily time step. The main regularities in the formation and development of anoxic conditions in different parts of the reservoir have been revealed. The factors that govern the space and time distribution of anoxic zones in the reservoir in different years have been identified. Empirical dependences of the volumes of anoxic zones on the characteristics of water mass stability in the reservoir and blooming index, which characterizes the rate of primary production in reservoir ecosystem, have been obtained. The identified trends toward an increase in anoxic zone volumes over the period under consideration characterize the progressive eutrophication of the Mozhaisk Reservoir.