scholarly journals Pokrovsko-Yakutsky reach of the Lena River: transformation of complex conjugated channel, recent deformations and management of channel changes

2019 ◽  
pp. 83-96
Author(s):  
R. S. Chalov ◽  
A. S. Zavadsky ◽  
D. V. Botavin ◽  
P. P. Golovlev ◽  
E. A. Morozova ◽  
...  
Keyword(s):  
Sediment Accumulation ◽  
Emergency Situation ◽  
System Transformation ◽  
Channel Processes ◽  
Valley Bottom ◽  
Channel Deformations ◽  
Local Conditions ◽  
Channel Changes ◽  
Lena River ◽  
Near Shore

The article considers the conditions of conjugate branches system transformation into parallel-branched channel, which are the most complex morphologically (by the mode of deformations and management) on the example of the Pokrovsko-Yakutsky section of the middle Lena River basin in the 21st century. It may arise from the general increase in the Lena Rivers water content and thawing frozen soils (composing shallow waters and near-shore shallows), as well as from the development of sleeves with unstable channel. At the same time, local conditions encouraged to the formation of a complex single (three-arm) branching at the beginning of the expansion of the valley bottom and the channel below city of Pokrovsk, the preservation of a straight unbranched channel upstream, the channel of the same type below the Tabaga Cape and alternating one-side branching at the end of the site. The modern riverbed reformation after the changes occurred consists in the transgressive displacement of floodplain-island massifs, intensive banks erosion, and the sediment accumulation zones formation. This has led to the significant complications in the river water usage (including water intake and port water areas sedimentation, creation an unfavorable environment in the port approaches area, berths and industrial infrastructure) and to creation of an emergency situation at the coastal infrastructure facilities. The revealed channel deformations regularities on the basis of long-term and modern researches and hydrodynamic modeling allowed to develop and justify the complex scheme of channel processes management, which implementation will allow to reduce or neutralize their adverse or dangerous manifestations.

scholarly journals Yakutsk Water Agglomeration at the Lena River – Channel Processes Problems: History, Current State, Prospect, and Possibilities of Control

2012 ◽  
pp. 44-56
Author(s):  
Keyword(s):  
Flow Line ◽  
River Channel ◽  
Main Trend ◽  
Channel Processes ◽  
Channel Deformations ◽  
Lena River ◽  
Current State ◽  
Valley Side ◽  
Predictive Assessment ◽  
The Right

The paper presents results of the analysis of the Lena River channel deformations near the Yakutsk City over the period exceeding the past 100 years. The data presented enables to conclude that the main trend of the channel development over that period has been a transformation of the adjoint braids pattern into the parallel arms pattern accompanied with directed migration of the main flow line towards the right valley side along the entire studied reach. Such a tendency of channel evolution creates an unfavorable situation for operations of the Yakutsk water industry and transportation facilities. The paper also gives a predictive assessment of the future channel deformations and proposes a set of channel regulation measures aimed at improving the situation.

scholarly journals Improvement of the method of combined plans for the analysis of channel re-formations of a water body on the example of the oka river section

2021 ◽  
Vol 2131 (3) ◽  
pp. 032076
Author(s):  
M Matugin ◽  
D Miltsin ◽  
M Reshetnikov ◽  
A Mazgaleva
Keyword(s):  
Water Body ◽  
Vertical Channel ◽  
River Channel ◽  
Qualitative Assessment ◽  
Channel Processes ◽  
Channel Deformations ◽  
Channel Changes ◽  
River Bed ◽  
The Stability ◽  
Vertical Deformations

Abstract The article discusses the ways of improving the method of combined plans for a water body channel reformations analysis on the example of a section of the Oka River. The main disadvantages of the existing classical approach to the analysis of channel processes through the channel surveys separate isobaths’combination are highlighted. A new approach to combining digital models of the river bed relief obtained from the hydrographic surveys results is proposed. Two directions of surface comparison are shown for the subsequent analysis of channel processes. For a qualitative assessment of channel changes, it is proposed to construct a new surface of vertical deformations and visualize it in color gradation or using lines of equal vertical deformations. For a quantitative assessment of channel processes, the use of a cartogram of vertical channel deformations is considered, and the numerical parameters for assessing the stability of the river channel are introduced. For the considered section of the Oka river channel, the main indicators of channel processes were obtained and analyzed using the proposed updated method. Separately, the calculation of the most optimal grid size was performed when constructing a cartogram of vertical channel deformations.

scholarly journals The conditions for occurrence of critical flow regime of water in the open stream

2019 ◽  
Vol 97 ◽  
pp. 05006
Author(s):  
Yuliya Bryanskaya ◽  
Aleksandra Ostiakova
Keyword(s):  
Froude Number ◽  
Flow Regime ◽  
Water Flow ◽  
Practical Interest ◽  
Open Water ◽  
Critical Regime ◽  
Critical Flow ◽  
Channel Processes ◽  
Channel Deformations ◽  
Critical Flow Regime

For the solution of engineering problems require increasingly accurate estimates of the hydraulic characteristics of the water streams. To date, it is impossible to consider sufficiently complete theoretical and experimental justification of the main provisions of the theory of turbulence, hydraulic resistance, channel processes. The composition of tasks related to flows in wide channels, turbulence problems are of scientific and practical interest. Various interpretations of the determination of the critical Froude number in wide open water flows based on observations and theoretical transformations are considered. The conditions for the emergence of a critical regime of water flow in an open wide channel are analyzed in order to estimate the critical Froude number and critical depth. Estimates of the critical Froude number for laboratory and field conditions are given. The estimations allow us to consider the proposed approach acceptable for determining the conditions of occurrence of the critical flow regime. The General, physical interpretation of conditions of occurrence of the critical regime of water flow on the basis of phenomenological approach is specified. The results take into account the values of the components of the total specific energy of the section. This shows the estimated calculation. The results obtained theoretically make it possible to compare the above interpretations and determine their applicability, and the results of the analysis can be useful for the estimated calculations of flows in channels and river flows in rigid, undeformable boundaries and with minor channel deformations.

scholarly journals Channel processes of a small river heavily modified by human activities

2020 ◽  
Vol 163 ◽  
pp. 06011
Author(s):  
Aleksandr Varenov ◽  
Anna Tarbeeva ◽  
Dmitriy Botavin ◽  
Nadezhda Mikhaylova ◽  
Leonid Turykin ◽  
...  
Keyword(s):  
Human Impact ◽  
Water Discharge ◽  
High Sensitivity ◽  
Bank Erosion ◽  
Small Rivers ◽  
Channel Processes ◽  
Channel Changes ◽  
Volga Upland ◽  
Local Residents ◽  
Special Approach

Widely-spread small rivers are very poorly studied in relation to channel processes. The influence of local factors, high sensitivity to human impact, close connection with basin processes, and relatively low rates of channel changes distinguish them from medium and large ones and make it necessary to form a special approach to studies. Based on collection of long-term maps and local residents’ interviews, we reconstructed the transformation of channels in the Kudma River basin (the Volga Upland) for the last 200 years. Based on the bank erosion monitoring during 2011-2019 the modern rates of channel changes were revealed. We found that significant human impact is associated with the artificial channels cutoffs and draining of ponds which led to channel incision of the Kudma and Ozerka Rivers in the middle reaches and the transformation of floodplain into terrace. Agriculture development caused siltation of the upper reaches of rivers. The rivers of the forested part of the basin experienced the least human changes. From 2011 to 2019 the maximum rates of bank erosion were found to be within range of 0.3 to 2.7 m/year and supposed to be driven by peak water discharge.

scholarly journals Spatial and temporal patterns of sediment storage and erosion following a wildfire and extreme flood

2019 ◽  
Author(s):  
Daniel J. Brogan ◽  
Peter A. Nelson ◽  
Lee H. MacDonald
Keyword(s):  
Laser Scanning ◽  
Sediment Accumulation ◽  
Temporal Patterns ◽  
Burn Severity ◽  
Spatial And Temporal Patterns ◽  
Channel Network ◽  
Valley Bottom ◽  
Erosion And Deposition ◽  
Downstream Effects ◽  
Extreme Flood

Abstract. Post-wildfire landscapes are highly susceptible to rapid geomorphic changes at both the hillslope and watershed scales due to increases in hillslope runoff and erosion, and the resulting downstream effects. Numerous studies have documented these changes at the hillslope scale, but relatively few studies have documented larger-scale post-fire geomorphic changes over time. In this study we used five airborne laser scanning (ALS) datasets collected over four years to quantify valley bottom changes in two ∼15 km2 watersheds, Skin Gulch and Hill Gulch, after the June 2012 High Park fire in northern Colorado and a large mesoscale flood 15 months later. The objectives were to: 1) quantify spatial and temporal patterns of erosion and deposition throughout the channel network following the wildfire and including the mesoscale flood; and 2) evaluate whether these changes are correlated to precipitation metrics, burn severity, or morphologic variables. Geomorphic changes were calculated using a DEMs of difference (DoD) approach for the channel network segmented into 50-m lengths. The results showed net sediment accumulation after the wildfire in the valley bottoms of both watersheds, with the greatest accumulations in the first two years after burning in wider and flatter valley bottoms. In contrast, the mesoscale flood caused large net erosion, with the greatest erosion in the areas with the greatest post-fire deposition. Volume changes for the different time periods were weakly but significantly correlated to, in order of decreasing correlation, contributing area, channel width, percent burned at high and/or moderate severity, channel slope, confinement ratio, maximum 30-minute rainfall, and total rainfall. These results suggest that morphometric characteristics, when combined with burn severity and a specified storm, can indicate the relative likelihood and locations for post-fire erosion and deposition. This information can help assess downstream risks and prioritize areas for post-fire hillslope rehabilitation treatments.

scholarly journals Geography of braided rivers within the territory of Russia

2019 ◽  
Vol 151 (6) ◽  
pp. 20-34
Author(s):  
R. S. Chalov ◽  
E. R. Chalova
Keyword(s):  
River Channels ◽  
Channel Processes ◽  
Channel Changes ◽  
Braided Rivers ◽  
Meandering Channels ◽  
Russian Scientific ◽  
Different Types ◽  
Incised Channel ◽  
Structural Levels ◽  
First Time

The paper represents the geographical analysis of braided river channels development and distribution for the first time in Russian Scientific Literature. On asmall-scale map of Russia we display the distribution of braided channels on small and middle mountain, semi-mountain and plain rivers, in free and limited conditions of channel changes development (on rivers with wide floodplain and incised channel), which are determined by geologic-geomorphologic structure of the territory. On the large and largest rivers we distinguish braided reaches of different morphological types according to the MSU classification (single, conjugated, one-sided and alternate one-sided, sub-parallel branches, etc) and also bifurcations as aconsequence of meander cut-off which complicate the morphology of straight and meandering channels. Separately we display bifurcations on the other structural levels of channel processes development point mid-channel bifurcations on mountain reaches of large rivers, split channels and deltaic braided reaches. The causes of different types of braided channels development in different natural conditions are described.

scholarly journals Numerical modeling and forecast of channel changes on the river Lena near city Yakutsk

2019 ◽  
Vol 381 ◽  
pp. 65-71 ◽  
Author(s):  
Pavel Golovlyov ◽  
Ekaterina Kornilova ◽  
Inna Krylenko ◽  
Vitaly Belikov ◽  
Aleksandr Zavadskii ◽  
...  
Keyword(s):  
Negative Impact ◽  
Point Of View ◽  
Water Levels ◽  
Positive Trend ◽  
Equal Distribution ◽  
Channel Changes ◽  
Lena River ◽  
City Water ◽  
Infrastructure Maintenance ◽  
The City

Abstract. STREAM_2D software package was applied to retrospective and predictive simulations of the Lena River near city Yakutsk hydraulic and channel changes during ice-free period. The modelling results indicate significant correspondence of simulated water discharges distribution and water levels with observed ones for the period 2001–2016. Model has captured main erosion and depositional zones observed in the 2009–2016 years. Combination of typical monthly average hydrographs of 1 %, 10 % and 50 % return intervals was used as an initial parameter for 10-year channel changes forecast. According to the simulation results, degradation of the Adamovskaya branch will be continued, which is the most negative impact for the Yakutsk city infrastructure maintenance. At the end of the forecast period the equal distribution between Adamovskaya and Buorylarskaya channels is possible, which is a positive trend from the point of view of the city water supply system.

scholarly journals METHODS OF IMPROVING THE EFFICIENCY OF MONITORING OF CHANNEL DEFORMATIONS OF MOUNTAIN RIVERS NEAR BUILT-IN SETTLEMENTS: ON THE EXAMPLE OF THE BUKTYRMA RIVER

2018 ◽  
Vol 44 (1) ◽  
pp. 28-35 ◽  
Author(s):  
Talgat TAUKENOV ◽  
Kulchikhan DZHANALEEVA ◽  
Zhuldyz YERZHANOVA
Keyword(s):  
Public Space ◽  
Morphological Characteristics ◽  
Control Measures ◽  
Mountain Rivers ◽  
Channel Processes ◽  
Channel Deformations ◽  
Geoinformation Systems ◽  
The Earth ◽  
River Bed ◽  
Scientific Justification

The results of research on the development of methods for increasing the efficiency of monitoring the channel deformations of mountain rivers using the methods of aerospace studies of the Earth and geoinformation systems are presented. Examples are given of estimating channel deformations, compiling morphological characteristics of the valley, floodplain and river bed, determining the scheme for the development of channel processes using public space imagery, scientific justification for erosion control measures.

Modeling of channel processes in large rivers with the use of field data

2021 ◽  
Vol 9 (1) ◽  
pp. 87-102
Author(s):  
A.T. Zinoviev ◽  
◽  
A.V. Dyachenko ◽  
K.B. Koshelev ◽  
K.V. Marusin ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Anthropogenic Impacts ◽  
Three Dimensional ◽  
Large Rivers ◽  
Observation Data ◽  
Channel Processes ◽  
Channel Deformations ◽  
Study Section ◽  
In Situ Data

The paper deals with mathematical description of channel processes occurring in long sections of large rivers with a complex morphometry. To forecast negative manifestations of channel deformations, a computer model of river sediment transport in the study section is proposed. It is based on a three-dimensional (3D) / two-dimensional horizontal (2DH) flow model, a 2DH model of bed sediment transport and observation data. Comparative analysis of simulation results of channel processes in the Ob river section at the Barnaul water intakes and in situ data makes it possible to evaluate forecast capabilities of the designed model, in particular, for quantitative assessment of changes in channel topography of the study section caused by natural and anthropogenic impacts.

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