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Papers by Aleksey Sidorchuk
Вестник Московского университета. Серия 5. География, Apr 2, 2020
Advances in Environmental Research, 2015
Вестник государственного университета морского и речного флота им. адмирала С.О. Макарова, 2010
Water Resources, 2020
Linearized equations of two-dimensional hydraulics have been analyzed by the method of small pert... more Linearized equations of two-dimensional hydraulics have been analyzed by the method of small perturbations within a wide range of alluvial features sizes at large values of Froude numbers and hydraulic resistance. The preservation of three-dimensional effects in depth-averaged equations of motion, continuity, and deformation enabled the authors to identify domains with combinations of flow hydraulic characteristics that correspond to alluvial features of different size and morphology. The study confirmed the results of the earlier analysis for subcritical flows with small hydraulic resistance and showed new types of relationships between alluvial features morphology and the hydraulic characteristics of flow for flows with large Froude numbers and high hydraulic resistance. In addition, a relationship between the length of two-dimensional ultramicroforms and hydraulic resistance has been established. A new class of macroforms-two-dimensional macroforms-have been identified. The verification of the results of theoretical analysis by measurements data on the morphology of channel formations and hydraulic characteristics of the flow has shown that the analysis of linearized equations of two-dimensional hydrodynamics by small-perturbation method can be used to determine the morphology and dimensions of channel forms in both subcritical and supercritical streams. The step-pool systems in torrential streams in mountain rivers are analogues of antidunes (in supercritical flows) and ripples (in subcritical flows), obtained in large flumes with sand alluvium. Three-dimensional macroforms are most common in rivers. If such macroforms are well developed in wide channels (at flow width greater than the half-width of the macroform), their length is determined by channel depth. Macroforms in narrower channels cannot develop completely, and their lengths are limited by channel width and can be calculated only through this width.
Вестник Московского университета. Серия 5. География, Mar 1, 2021
Geomorfologiâ, Mar 19, 2015
Геоморфология, Jul 8, 2015
The hierarchical classification of Lower Volga channel landforms is put forward. The classificati... more The hierarchical classification of Lower Volga channel landforms is put forward. The classification consists of 8 complexes and 5 classes. The class of nanoforms includes riffles; microforms - dunes and zastrugas; mezoforms -sand waves and alternate bars; macroforms - big meanders and large ramification junctions; megaforms - ramifica-tions with parallel arms or the river. The main channel of Volga and its branch - Akhtuba form a parallel-channel system. Empirical probability density of channel forms length (for each class) may be fitted well by Gamma distribu-tion; the height may by fitted by Weibull distribution.
Geomorfologiâ, Feb 21, 2015
Fractal dimensions of the more than 200 large river networks of the former USSR were calculated. ... more Fractal dimensions of the more than 200 large river networks of the former USSR were calculated. We use the term «fractal» as «a structure consisted of parts which are in some sense alike to the whole». River networks don’t possess the complete self-likeness – fractal dimension changes with the change of measurer unit and the chosen length of the rivers. Therefore the calculations were fulfilled with the measurer length lying within the limits of 1–10 km. Fractal dimension of the river networks of the former USSR changes from 1.1 to 1.7, which corresponds to the aggregate length of the short rivers (1–10 km) consisting 20–80% of total river network length. Then all studied networks have fractal dimension more than Euclidian dimension of line (1) and less than Euclidian dimension of plane (2) as it should be accordingly to the fractal approach. There is a tendency for fractal dimension to grow with the height of the river basin and humidity of the territory. It is also strongly correlated with the network density. Fractal dimension as an index of the river length distribution has some advantages in comparison with the other morphometric indexes used. It augments significantly the possibility of the quantitative analysis of the drainage networks.
Pages (Bern), Dec 1, 2000
Water, Jan 7, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Springer proceedings in earth and environmental sciences, 2019
Climate change is one of the main factors of the modern erosion. Much less investigated the influ... more Climate change is one of the main factors of the modern erosion. Much less investigated the influence of accelerated erosion on climate change due to greenhouse gases emission. Healthy modern soils are the sinks for atmospheric carbon. Washed-out and buried soils (stratozems) are the sources of atmospheric carbon. The modern emission of carbon dioxide from this formed by accelerated erosion pool of carbon is small and does not affect significantly the CO2 budget in the atmosphere.
Springer proceedings in earth and environmental sciences, 2019
The empirical three-dimensional hydraulic gully erosion and thermo-erosion model GULTEM was used ... more The empirical three-dimensional hydraulic gully erosion and thermo-erosion model GULTEM was used to calculate the surface runoff optimal to form ancient periglacial dry valleys on the East European plain.
Geomorfologiâ, Jul 8, 2015
HAL (Le Centre pour la Communication Scientifique Directe), 2016
no abstrac
Water Resources, Mar 1, 2017
Active bed forms of three major classes are formed in Terek lower reaches during summer floods. T... more Active bed forms of three major classes are formed in Terek lower reaches during summer floods. They include ripples, dunes of the first order, and dunes of the second order (from smaller to larger), which commonly form an incomplete hierarchy. The morphology of the bed forms is essentially stochastic and can be adequately described by probability distribution functions of bed form characteristics for some narrow ranges of hydraulic flow characteristics. At the same time, the mean values of bed form morphometric characteristics (length, height, and asymmetry) show stable relationships with flow velocity and depth. The celerity of active dunes can be adequately described by a modified Snishchenko-Kopaliani formula. The channelforming sediments that move as bed forms in Terek lower reaches account for 7% of sediment transport rate of all channel-forming sediments, a value near the lower limit for rivers with sand alluvium.
Вестник Московского университета. Серия 5. География, Apr 2, 2020
Advances in Environmental Research, 2015
Вестник государственного университета морского и речного флота им. адмирала С.О. Макарова, 2010
Water Resources, 2020
Linearized equations of two-dimensional hydraulics have been analyzed by the method of small pert... more Linearized equations of two-dimensional hydraulics have been analyzed by the method of small perturbations within a wide range of alluvial features sizes at large values of Froude numbers and hydraulic resistance. The preservation of three-dimensional effects in depth-averaged equations of motion, continuity, and deformation enabled the authors to identify domains with combinations of flow hydraulic characteristics that correspond to alluvial features of different size and morphology. The study confirmed the results of the earlier analysis for subcritical flows with small hydraulic resistance and showed new types of relationships between alluvial features morphology and the hydraulic characteristics of flow for flows with large Froude numbers and high hydraulic resistance. In addition, a relationship between the length of two-dimensional ultramicroforms and hydraulic resistance has been established. A new class of macroforms-two-dimensional macroforms-have been identified. The verification of the results of theoretical analysis by measurements data on the morphology of channel formations and hydraulic characteristics of the flow has shown that the analysis of linearized equations of two-dimensional hydrodynamics by small-perturbation method can be used to determine the morphology and dimensions of channel forms in both subcritical and supercritical streams. The step-pool systems in torrential streams in mountain rivers are analogues of antidunes (in supercritical flows) and ripples (in subcritical flows), obtained in large flumes with sand alluvium. Three-dimensional macroforms are most common in rivers. If such macroforms are well developed in wide channels (at flow width greater than the half-width of the macroform), their length is determined by channel depth. Macroforms in narrower channels cannot develop completely, and their lengths are limited by channel width and can be calculated only through this width.
Вестник Московского университета. Серия 5. География, Mar 1, 2021
Geomorfologiâ, Mar 19, 2015
Геоморфология, Jul 8, 2015
The hierarchical classification of Lower Volga channel landforms is put forward. The classificati... more The hierarchical classification of Lower Volga channel landforms is put forward. The classification consists of 8 complexes and 5 classes. The class of nanoforms includes riffles; microforms - dunes and zastrugas; mezoforms -sand waves and alternate bars; macroforms - big meanders and large ramification junctions; megaforms - ramifica-tions with parallel arms or the river. The main channel of Volga and its branch - Akhtuba form a parallel-channel system. Empirical probability density of channel forms length (for each class) may be fitted well by Gamma distribu-tion; the height may by fitted by Weibull distribution.
Geomorfologiâ, Feb 21, 2015
Fractal dimensions of the more than 200 large river networks of the former USSR were calculated. ... more Fractal dimensions of the more than 200 large river networks of the former USSR were calculated. We use the term «fractal» as «a structure consisted of parts which are in some sense alike to the whole». River networks don’t possess the complete self-likeness – fractal dimension changes with the change of measurer unit and the chosen length of the rivers. Therefore the calculations were fulfilled with the measurer length lying within the limits of 1–10 km. Fractal dimension of the river networks of the former USSR changes from 1.1 to 1.7, which corresponds to the aggregate length of the short rivers (1–10 km) consisting 20–80% of total river network length. Then all studied networks have fractal dimension more than Euclidian dimension of line (1) and less than Euclidian dimension of plane (2) as it should be accordingly to the fractal approach. There is a tendency for fractal dimension to grow with the height of the river basin and humidity of the territory. It is also strongly correlated with the network density. Fractal dimension as an index of the river length distribution has some advantages in comparison with the other morphometric indexes used. It augments significantly the possibility of the quantitative analysis of the drainage networks.
Pages (Bern), Dec 1, 2000
Water, Jan 7, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Springer proceedings in earth and environmental sciences, 2019
Climate change is one of the main factors of the modern erosion. Much less investigated the influ... more Climate change is one of the main factors of the modern erosion. Much less investigated the influence of accelerated erosion on climate change due to greenhouse gases emission. Healthy modern soils are the sinks for atmospheric carbon. Washed-out and buried soils (stratozems) are the sources of atmospheric carbon. The modern emission of carbon dioxide from this formed by accelerated erosion pool of carbon is small and does not affect significantly the CO2 budget in the atmosphere.
Springer proceedings in earth and environmental sciences, 2019
The empirical three-dimensional hydraulic gully erosion and thermo-erosion model GULTEM was used ... more The empirical three-dimensional hydraulic gully erosion and thermo-erosion model GULTEM was used to calculate the surface runoff optimal to form ancient periglacial dry valleys on the East European plain.
Geomorfologiâ, Jul 8, 2015
HAL (Le Centre pour la Communication Scientifique Directe), 2016
no abstrac
Water Resources, Mar 1, 2017
Active bed forms of three major classes are formed in Terek lower reaches during summer floods. T... more Active bed forms of three major classes are formed in Terek lower reaches during summer floods. They include ripples, dunes of the first order, and dunes of the second order (from smaller to larger), which commonly form an incomplete hierarchy. The morphology of the bed forms is essentially stochastic and can be adequately described by probability distribution functions of bed form characteristics for some narrow ranges of hydraulic flow characteristics. At the same time, the mean values of bed form morphometric characteristics (length, height, and asymmetry) show stable relationships with flow velocity and depth. The celerity of active dunes can be adequately described by a modified Snishchenko-Kopaliani formula. The channelforming sediments that move as bed forms in Terek lower reaches account for 7% of sediment transport rate of all channel-forming sediments, a value near the lower limit for rivers with sand alluvium.