2025 , Volume 30, № 5, p.21-31

Quantification of the mass of agitated sediments is an integral part offor solving of the problem related to pollution due to the secondary heavy metal pollution problemmetals. This estimation is inextricably linked with the solution of the two-phase mass transfer equations. The authors developed algorithms for assessing secondary pollution of water bodies and carried out numerical modelling of the bottom sediment agitation processes using the example of the Kuibyshev reservoir Dammedbasin with copper (its gross content). The proposed model is based on both the hydrodynamic equations of “shallow water” andequations and related algorithms offor two-phase mass transfer, which is implemented on a regular rectangular grid with a step of 200 meters step. The mechanism of heavy metals (HM) entering the water mass from bottom sediments in the model is describedmodelled by the convective-diffusion equation of conservative impurity transfer, which takes into account accounts the flow of the total mass of HM adsorbed on the surface of transported particles of a certain size, as well as the flow of HM coming from the pore waters. At the same time, in contrast to the accepted algorithms for assessing of the heavy metals load on bottom sediments of effective size, the curve of the granulometric composition of bottom sediments is taken into account. A series of model calculations has been carried out and of the gross copper distribution maps content in the water area of the Kuibyshev reservoir near the dam under conditions of runoff and wind currents of different directions have been obtained. It was found that the highest values of the gross copper content for calm conditions occur in the places of the most hydrodynamically active runoff currents, namely the Klimovskoye narrowing and the area immediately in front of the Zhiguli hydroelectric dam. The results of modelling two-phase mass transfer under unfavorable hydrometeorological phenomena (dominant winds of the south-west and north-west directions with a speed of 15 m/s) showed an excess of background concentrations in the northern part of the Kuibyshev reservoir Dam water area by 2–6 times. The proposed calculation method and the developed model make it possible to quickly predictallows quick predicting for the gross content of HM in water bodies when making decisions on additional water purification at intake facilities in the event of a threat of increased wind.