Особливості руслових процесів на гірських річках в межах Ворохто-Путильського низькогір’я (басейн Черемошу)

Abstract

Стаття присвячена визначенню особливостей руслових процесів гірських річок, що протікають в межах Ворохто-Путильського низькогір’я. Це зокрема річки, що відносяться до басейну Черемошу: його гідрографічні витоки ріки Чорний та Білий Черемош, та їх менші допливи. Головною особливістю руслових процесів на річках в межах досліджуваного регіону є непропорційно широкі днища долин, які неспівставні із сучасним розмірами русел. Другою особливістю є переважання алювіального типу русел, з добре обкатаними наносами в межах даного геоморфологічного району. Важливим елементом досліджень сучасних руслових процесів на річках, є зйомка поперечного перерізу русла, на ключових ділянках, що дозволяє більш обґрунтовано і точно проводити аналіз зон затоплень під час проходження катастрофічних паводків та інтенсивності вертикальних деформацій навіть при відсутності регулярних спостережень на досліджуваних водних об’єктах.

This publication is devoted to the study of the features of channel processes on mountain rivers that cross the Central synclinorium of the Ukrainian Carpathians, namely the region of the Vorokhto-Putilsky low mountains. These are mainly the rivers of the Cheremosh river basin, the hydrographic sources of the Black and White Cheremosh, as well as their small tributaries Iltsa and Richka. It is within the boundaries of this geological and geomorphological region that atypical hollow expansions of the bottoms of river valleys are observed (Zhabeevskaya, Krivopilskaya, Iltsevskaya, Krivorivnesvkaya and Yablunetskaya). According to the data of some researchers, the zone of the Vorokhto-Putyl low mountains is part of an older river runoff, the so-called Yasynya-Cheremoshskaya River, which is fragmentarily represented in the modern orography of the Ukrainian Carpathians and is currently not a homogeneous morphological structure. This old river, during the Pliocene period, had an internal flow into the basin of the Siret River, in the direction of its tributary, the Moldova River. It is in this zone that high terrace levels (VIII, IX) are well preserved, the direction of which does not correspond to modern river valleys. The main feature of the channel processes of the rivers in this particular region is the disproportionate size of the bottoms of their valleys in accordance with the modern dimensions of the channels. The second feature is the predominantly alluvial type of channels with a clearly expressed thick bottom pavement, as well as alluvial forms with well-rounded sediments. An important modern element of modern scientific studies of channel processes is the measurement work in the channel to measure the depths of the river channel and the subsequent construction of the transverse profile of the river in certain key areas. The results of these measurements, as well as the graphs of the transverse profiles themselves, are presented in this paper for the Iltsa, Chorny, and Bely Cheremosh rivers. A brief description of the features of the channel processes in the leveling areas is also given. The obtained results make it possible to more reasonably and accurately analyze the flood zones of these rivers during the passage of floods and spring floods. And also, based on a comparison of the graphs of transverse profiles for different periods, it will be possible to more accurately assess the vertical deformations in different parts of the channels of the studied rivers. Thus, for most riverbeds crossing the Vorokhta-Putilsky terraced lowlands, we see atypical hollow expansions of valley bottoms, which indicate local changes in geological and homorphological conditions in these areas, which in turn affects the formation of alluvial type of channels, with quite a large number of deposits of good run-in. This type of channel is more typical of rivers flowing within the foothills and more reminiscent of the free conditions of channel formation. At the same time, when moving to the area of the Skibov Carpathians, the incised type of channel becomes predominant again. It should also be noted that the development of channel macroforms (incised macro-meanders on the rivers Iltsa, Chorny Cheremosh, Rivers) is observed within this lowland, which indicates a complex hierarchy of channel processes in this geomorphological zone. Prospects for the use of results. The obtained results give the starting material for further, deeper, study and determination of the peculiarities of channel processes on the studied mountain rivers: due to the cross-sections it is possible to calculate the channel-forming water flow at given speeds and water levels; repeated leveling, after a certain period of time, will allow to estimate the intensity of vertical and planned deformations in the surveyed areas; it became possible to determine the zones of flooding during high floods by mathematical (calculation) methods, even in the absence of regular observations at the object of research and to estimate the coefficient of stability of the riverbed.