Computer modeling of a non-stationary regime of distribution of the wastewater of Togliatti city in the coastal zone of the Bakhilovsky Island of the Middle Volga Integrated Biosphere Reserve (Saratov Reservoir, the Volga River, Russia)

Abstract

The formation of the pollution zones in the coastal water area of the Bakhilovsky Island belonging to the Middle Volga Integrated Biosphere Reserve was examined under the influence of a large source of wastewater discharge from the Togliatti city taking into account different phases of the daily flow regime of the Saratov Reservoir (the Volga River, Russia). Numerical simulation methods were used to calculate the flow fields and the transfer of the wastewater lenses at various water flow rates at the Zhigulevsk hydroelectric complex. Three typical scenarios for regulating water discharge were calculated: at night, during the day, and during the regulating releases. According to model calculations, the maximum pollution zone is formed in the area of wastewater discharge and in the vicinity of the Bakhilovsky Island during long-lasting regulating releases in the summer-autumn low-water period. The maps of the sewage plume distribution were developed, and vulnerable zones were defined for subsequent environmental monitoring of the water quality in the water area surrounding the protected island.