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Geography and Natural Resources

2021 year, number 2

MORPHODYNAMICS AND HYDROLOGIC-MORPHOLOGICAL CHARACTERISTICS OF THE MIDDLE OB RIVERBED AT THE LATITUDINAL STRETCH

R.S. CHALOV, A.A. KAMYSHEV, A.S. ZAVADSKY, A.A. KURAKOVA
Lomonosov Moscow State University, 119899, Moscow, Leninskie gory, 1, Russia
Keywords: river bed processes, forked river bed, bends, branching, reconfigurations, bank erosion

Abstract

This article presents for the first time the hydrologic-morphological and morphodynamic characteristics of the river bed of the latitudinal stretch of the middle Ob within the Khanty-Mansiisk Autonomous Okrug - Ugra (upstream of the mouth of the Irtysh river). The assessment of the river bed deformations is based on the expedition-based data obtained in 2018, the analysis of satellite images, pilot charts and plans of channel bars for different time intervals. The morphodynamic types of river bed, the conditions and patterns of their distribution and alternation along the length of the river are determined; the characteristics of the river bed morphology and dynamics of each of the occurring morphodynamic types are assessed: a relatively straight line and unbranched; gentle, steep and straightening of rivers bends; single, floodplain-river bed, and complex three-branch and conjugate branching. For the first time, we assessed the impact of the river division into two independent branches forming the bifurcated river bed-the right river bed (the main as regards the discharge), and the left river bed, represented by the Yuganskaya Ob, Bolshaya Salymskaya and Neuliov river duct system. Also for the first time, complex three-branch forks with meandering branches are identified. Differences in the formation of the bends of the river bed, the bends of the branches of the forked river bed and river bed branches are revealed. The analysis of the bends was carried out using conventional techniques as well as statistical methods which allowed us to obtain empirical curves of availability and distribution density of their main morphological parameters: the radii of curvature, and steps and degrees of development of the river bends. Forks of different types were considered and the specificity of the complexity of the forks was revealed by comparing them with forks in the upstream sections of the middle and upper Ob river bed.