Mathematical modelling of spatial-temporal variability of phosphorus content and phytoplankton development in the Kuibyshev reservoir

Abstract

The article is dedicated to simulation of phytoplankton biomass growth dynamics amidst flow control in one of the biggest flowing water reservoirs in the world – the Kuybyshev Reservoir. Uniqueness of this natural-technical water body with such large area is pre-defined by significant spatiotemporal changes in physical, chemical and biological parameters, specifying quality and ecological condition of aquatic environment. Studies are conducted using materials of full-scale hydro-ecological observations in the reservoir within vegetation period, in 2016. Some simulation exercises were performed on the model. The model is developed based on hydro-thermodynamics equations and empirical dependences of phosphorous limitation of phytoplanktonic community biomass growth, which is implemented in VOLNA authorial software envelope. The calculation was performed on rectangular spatial grid with spacing of 200 m and timed discretization of 1 day. Within full-scale observations, initial information is acquired, model parameters are calibrated and quality of performed calculations is assessed. Simulation modelling of seasonal phytoplankton field dynamics in Kuybyshev reservoir were analysed using 2D-model of phyto-phosphorous system and results were represented. According to calculations data, phytoplankton biomass growth along reservoir length from headstream to Zhigulevsk HPP dam is observed, as well as intense water blooming locations were detected in estuarial areas and shallow-water parts of the reservoir.