Modeling of Quantitative and Qualitative Characteristics of the Neva River Runoff Under Conditions of External Influences on the Catchment

Two tasks related to the study of environmentally safe water supply in St. Petersburg have been solved. These are predictive estimates of possible changes in the runoff of the Neva River as a result of climate change and the possible consequences of an emergency at the Krasny Bor toxic wastes landfill. The tasks were solved using the methods of mathematical modeling. Scenarios RCP 2.6 and RCP 8.5 are taken as the basis for predicting possible climate changes - the best and worst in terms of environmental impact. Runoff calculations using the specified climate scenarios showed an increase in runoff under the RCP 8.5 scenario and its decrease under the RCP 2.6 scenario. It has been established that the process of dilution of discharged pollutants from the Krasny Bor landfill as they transport towards the water intakes of St. Petersburg depends on the emergency scenario, hydrological conditions, and the choice of maximum permissible concentrations value for each chemical. The negative impact of the destruction of the embankment of pits with pollutants may be insignificant for municipal water intakes due to dilution processes in the hydrographic network of the catchment. At the same time, hypothetical catastrophic scenarios (terrorist attack, earthquake) in some cases can lead to serious problems with water quality in municipal water intakes.