MODELING OF WATER BLOOMS IN THE KUIBYSHEV RESERVOIR IN YEARS WITH DIFFERENT FLOW REGULATION REGIME

Abstract

The article studies the influence that the dynamics of currents have on algal blooms in the Kuibyshev Reservoir in the conditions of an unsteady flow regime. One of the ways to improve the ecological condition of the reservoir is to reduce cyanobacteria blooms by increasing the flow rate during the maximum warming of the water. The hydrodynamics of the aquatic environment is considered as a regulatory factor that reduces the negative effects of eutrophication and improves the quality of water in the reservoir. The author performed full-scale hydroecological observations in the summer periods of 2016 and 2017 and made model calculations of the dynamics of currents and spatial distribution of phytoplankton in the water area of the Kuibyshev Reservoir. As a result, the dependence of the chlorophyll a index (Chl a) on the flow regulation regime was established. The proposed model is based on the equations of long-wave hydrodynamics, known as the shallow-water equations, the equations of convective transport and development of the components of the ecosystem, which is implemented in the author’s software environment VOLNA. The model is constructed for the near-dam water area on a regular rectangular grid with a step of 200 m. The model was verified on the basis of data from field observations, and the quality of the calculations performed was evaluated. It has been found that the phytoplankton biomass index (Chl a) is related to the water flow velocity non-linearly and varies according to a power law. The conducted studies give reason to believe that the intensity of cyanobacteria blooms largely depends not on the water content of the year, but on the intra-annual redistribution of runoff.