Mathematical Modeling of Thermal Regime and Dissolved Oxygen Dynamics in the Kuibyshev Reservoir

Abstract

The purpose is to estimate spatial and temporal patterns of distribution of water temperature fi elds and dissolved oxygen concentration in the water area of the Kuibyshev reservoir under conditions of a hot year using a mathematical model. Materials and methods. A numerical 2D spatially inhomogeneous model of the dynamics of water temperature fi elds, primary production and dissolved oxygen content has been developed. The model describes the formation of the oxygen regime taking into account the unsteady fl ow regime and uneven warming of the reservoir water area with a spatial step of 200 meters and a daily time step. Results and discussion. On the basis of numerical experiments, the convection of the temperature fi eld, the dynamics of oxygen dissolved in water and primary production in the Kuibyshev reservoir during the ice-free period are studied. Diff erent-scale zones of the water area with diff erent warming of the water column and oxygen content have been identifi ed. It is shown that in autumn the spatial heterogeneity of water temperature is about three times higher than in spring and summer periods. There is a large contribution (>50 %) of phytoplankton photosynthesis to the overall oxygen balance during the fl owering period. Conclusion. Maps of the spatial distribution of water temperature, dissolved oxygen content and primary production in the hottest year of 2016 in the last 10 years have been obtained. The comparison of the calculated and full-scale values of the indicators was evaluated by the Tail criterion, which showed satisfactory convergence. This makes it possible to use the developed model for further studies of the current state of the Kuibyshev reservoir.