[A-HW22] River Channel Morphology, Water Resource Management, and Advanced Techniques

[AHW22-P13] Danger of riverbank erosion in Western Siberia

*Anna Kurakova¹ (1.Lomonosov Moscow State University, 119991, Moscow, Russia)

Keywords:riverbank erosion, Western Siberia, fluvial process

Riverbank erosion is a dangerous fluvial process that can lead to emergencies and destroy engineering structures, economic and other facilities located on banks and in river channels, and can also serve as a source of sediment entering the river channel that may be contaminated with radionuclides, heavy metals and other pollutants. Assessing bank erosion is particularly important for Western Siberia, Russia's most important oil and gas region, and the location of the Mayak PA, where bank erosion is common. Based on the extensive database of satellite images and its processing, a complete bank erosion database has been created for the first time for 31 plains rivers of Western Siberia, covering about 20,000 km of their length. Medium and most large rivers of Western Siberia are characterized by relatively low rates of bank erosion (not more than 3 m/year), while on the largest rivers (Ob and Irtysh) and in the lower reaches of some large rivers (Tom, Chulym, Tobol) the rate of bank erosion increases, sometimes reaching 7 m/year and more. Western Siberia is characterized by increased rates of bank erosion in the west and south-east of the study area, which decrease towards the north and center. This is due to the general increase in these directions of natural flow regulation by bogs and lakes, the occurrence of permafrost in the northern areas, and the change in the intra-annual distribution of runoff (snow-feeding in spring in the south and near the Urals, and ground-feeding in summer in the north) as a result of changes in the temperature regime, precipitation regime, and hydrogeological structure of the area. The rivers in south-eastern West Siberia, which have a well-divided catchment relief and minimal natural flow regulation, are characterized by increased bank erosion activity: average rates are more than 3 m/yr and maximum rates are more than 12 m/yr. In the rivers of the highly waterlogged central Ob basin, bank erosion rates rarely exceed 2 m/year. In the northern rivers, the intensity of bank erosion has a wide range, decreasing slightly from south to north. This is due to the variety of natural conditions influencing water flow: rugged relief, variability of land cover and wetlands, permafrost, etc. Of great importance is the composition of the river banks, with easily erodible loose sediments, which can cause high rates of bank erosion in the case of high flow regulation by swamps, as observed in the rivers near the Urals: average - about 2 m/year, maximum - up to 7 m/year. The largest rivers in the basin, the Ob and the Irtysh, are characterized by a wide range of bank erosion rates. This is due to the fact that they are polyzonal rivers and flow through several landscape-hydrological regions. The integral assessment of the level of bank erosion hazard on the rivers of Western Siberia shows significant differences in the development of hazardous fluvial process on different rivers. The Ob and Irtysh rivers show both a high level of bank development and an increased intensity of bank erosion and, consequently, a hazard level that leads to a significant risk of infrastructure destruction. At the same time, the northern rivers and most of the tributaries of the Ob and Irtysh are characterized by a lower hazard due to less development and lower rates of bank erosion. The largest rivers, such as the Ob and Irtysh, are characterized by real hazard, while medium and large rivers are mainly characterized by potential hazard.
This work was supported by the grant of the The Government of the Russian Federation (Agreement № 075-15-2024-614 date 13.06.2024).