ABIOTIC FACTORS AFFECTING THE ECOLOGICAL STATE OF LAKE NERO ACCORDING TO MATHEMATICAL MODELING. 2. TWO-PHASE MASS TRANSFER IN THE WATER AREA

Abstract

For the shallow Lake Nero, calculations of currents, sediment transport and the intensity of bottom reformation in various hydrometeorological situations were performed. The calculations were carried out using a two-dimensional model of currents and sediment transport in a shallow reservoir and an analytical formula for sediment discharge developed at the Institute of Limnology of the Russian Academy of Sciences. Numerical experiments have been carried out to assess the possible consequences of the implementation of two design solutions aimed at improving water exchange for the recovery of Lake Nero. According to the first decision, it was planned to excavate bottom sediments within the city limits of Rostov in order to increase the depths in the coastal zone of the lake. Calculations showed that for a section of the water area with a deep bottom, the current velocities decrease several times (in some areas, to zero values). The sediment rate will slightly increase directly in the deepening section due to the increase in the cross-sectional area of the flow. Therefor this event will not bring any positive effect. The second project proposal was to be aimed at increasing the transit capacity of the longitudinal section of the aquatic area from the mouth of the main tributary of Sara River to the inflow of Veksa River. Calculations have shown that an increase in depth along the indicated trajectory while maintaining the transferred amount of water masses will also lead to a decrease in the speed of currents. Based on the simulation, it can be concluded that the practical implementation of the presented design solutions will not lead to an improvement in water exchange in the lake, but also vice versa, will contribute to the formation of stagnant zones, especially for the first proposed design solution.