Geology-geomorphology factors of the structure and dynamics of the fluvial systems in the Upper Dnieper

Features of territory geological and geomorphological structure manifest themselves in morphology, spatial structure and dynamics of fluvial relief. The influence of the factor has a probabilistic nature in connection with the accounting complexity for the interaction of the related fluvial forms, diversity of their spatial combinations. At the level of individual bends of the meandering channel a significant impact on the dynamics is the strength properties of channel-forming grounds. For the middle course of the Desna River a direct link between the intensity of the longitudinal and transverse channel deformations and their comprehensive strength parameter (resistance to erosion and average-maximal channel-forming discharge) is established. The most stable is the bend whose slopes are composed of strong loam rocks, fast configuration changes are characteristic of the segment bend in a sandy alluvium. The spatial structure of the floodplain-channel complexes, which is forms of organization of fluvial relief on the level between individual forms and hydrological networks, reflects the influence of the rock strength characteristics through the correlation of different bend types. Indicator characterizes the specifics of the process in different geological-geomorphological conditions. In the left-bank part of the basin of the Upper Dnieper the ratio is made of bends in the river crossing morainal, fluvial-glacial plains with different depth of pre-Quaternary rocks, loess plateaus. Features of dynamics of floodplain-channel complexes manifested in the scale of morphodynamic and morphological changes, the sustainability of individual forms typical transformation non-definitely reflect the specifics of the geological and geomorphological structure of the territory of the basin. Non-uniformity of the relief development speed in the scale of thousands / tens of thousands square kilometers is manifested in the difference of the hydrological networks structure from the classical erosion scheme. Deviations appear in violation of the connection sequence of watercourses. Small rivers of the first and the second orders directly flowing into the major river constitute a substantial share in the hydrological networks of the left bank of the Dnieper basin. Such streams are much larger than the classical upper elements of the erosion network. The main reason for the deviations is the interception of the flow part by the neighboring catchment basin. The influence of geological and geomorphological features on the dynamics and spatial structure of fluvial relief is significant for forms with a typical development period of several decades: bends of the modern channel, and less clearly - higher levels of its organization. The dependencies have a probabilistic character, defined by the dynamics of both related, and relatively remote similar forms, the impact of which is difficult to formalize. The specific methods for description of geological and geomorphological factors that depend on the model objects hierarchical level and the specificity of the region are justified.

Keywords

Authors

References