Ice impact on the flow dynamics the Northern Dvina River mouth area

Abstract

The authors consider case of the winter period 2019-2020 as example of ice cover and ice jam influence on the flow dynamics in the section upstream the delta of the Northern Dvina River mouth area. Hydrological monitoring, calculations and forecasts of the ice drift in the Northern Dvina River mouth area are actual practical tasks. The hydrological regime of a tidal river mouth is very complex phenomena and one of the most difficult for a quantitative description. The authors implemented an integrated approach to study ice jams, including field ice surveys, satellite data analysis, data from the state hydrological monitoring system and hydrodynamic modeling. STREAM_2D CUDA software is applied for two-dimensional numerical modeling. It takes into account the impact of ice cover. Ice phenomena usually make significant changes in the water level and velocity regime. In 2019/2020 hydrological year the ice cover provided and maintained a large backwater during all the autumn and the winter. When the spring ice drift came from the river upstream there was a 3-4 meter water level rise, which lasted for 5 days, creating a threat of flooding of the Kholmogory village by a breakthrough wave. There is no effective technique to forecast or assess probable scenarios for such situation. The article identified difficulties arising during ice conditions analysis and hydrodynamic modeling of the situation. Steps to optimize the monitoring of ice cover, flow discharges and water levels are also formulated