MORPHODYNAMIC CLASSIFICATION OF CHANNEL OF SUKIL RIVER

Abstract

The morphodynamic classification of the Sukil river channel made it possible to determine the hydromorphological processes and to study the factors that determine them. The channel was classified according to the method of R.S. Chalov. Three main classification criteria were taken into account: the geomorphological type of conditions for the formation of the channel; the type of channel processes; the mophrodynamic type of channel. According to the geomorphological type of channel-forming conditions, the channel is divided into the incised channel – located mainly in mountainous and semi-mountainous parts with a characteristic the narrow valley, laid in sandstones, siltstones, and argillites; confined channel – located in intermountain basins, with one bank of channel composed of bedrock, and the other – of Quaternary sediments; wide-floodplain channel – mainly located in the lower part of the channel on the Stryi-Zhydachiv basin, laid in the Quaternary deposits of loams and sands. According to the type of channel processes, the channels with developed alluvial forms and without developed alluvial forms are dominant. Together they make up 2/3 of the channel. Other types of channels are wide-floodplain – characterized by slow flow and stable development of the meandering process, and rapid-waterfall – located in the upper reaches of the channel. The latter is characterized by a stormy current and the presence of numerous rapids made of boulders and wood. There are 3 main morphodynamic types of the channel – meandering, branched, and straightforward, and 6 their subtypes. Meandering, incised channels are characterized by structural meanders, their shores are composed of hard rocks, mostly sandstones. The meandering confined channels are defined by the root bank in the apical part and the upper wing along the root bank, which leads to the formation of segmental and blockage convolutions. Meandering, broad-flooded channels are characterized by longitudinal displacement of meanders, their convolutions are segmented, rarely loop-shaped. The coefficient of meandering gradually increases from the mountainous part of the channel to the plain one (1.10–1.35). Branched type is represented by a single complex and floodplain-channel subtypes. The size of the islands that divide the channel into arms is from a few meters to 350–400 m. The straightforward type of channel is widespread and is 1/3 of the total length of the river. Key words: channel type; straightforward; branched; meandering; incised; confined; floodplain.