Hydrology-Morphodynamic Characteristics and Reforming the Branched Channel in the Lower Reaches of the Ob River (within the Yamalo-Nenets Autonomous Okrug)

The article analyzes the conditions for the formation of the river channel and river morphology in the lower reaches of the Ob River within the Yamalo-Nenets Autonomous Okrug. Despite its important economic and water transport significance, the lower Ob River has remained practically unexplored until now. The geomorphological structure of the valley determines the formation of a wide-floodplain channel. The floodplain reaches 50 km across and narrows to 10 km only near Salekhard. For the first time, the bifurcated channel appears within the Khanty-Mansi Autonomous Okrug. The beginning of the bifurcated channel within the Yamalo-Nenets Autonomous Okrug is the Bolshoy Nyurik branch between the two main branches—Malaya Ob and Bolshaya Ob. Numerous floodplain channels branching off from the Malaya Ob reduce its water content to 10% of the total water. This is accompanied by a change in the river morphology and the parameters of riverbends. At the same time, the intensity of riverbank erosion decreases. In addition to the riverbends on the Malaya Ob, there are often segments of an unbranched channel. The Bolshaya Ob has an unbranched channel due to its location along the right valley side. Along with the data on water runoff dispersion, the data on the distribution of suspended load along the branches are presented during the flood. It is shown that its change is greatly influenced by riverbanks erosion and the floodplain branches, especially on the Malaya Ob. The obtained materials, in addition to general scientific value, are important for substantiating projects for water management and water transport development of the Ob River.

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