scholarly journals Morphological diversity of channel patterns of braided rivers

2019 ◽  
pp. 3-18
Author(s):  
R. S. Chalov
Keyword(s):  
Water Regime ◽  
Water Discharge ◽  
Morphological Diversity ◽  
State University ◽  
Channel Stability ◽  
Channel Processes ◽  
Valley Bottom ◽  
Braided Rivers ◽  
Braided Channel ◽  
Channel Patterns

The paper presents the description of main channel types of braided rivers distinguished in the channel pattern classification produced in the Moscow State University. It is shown that the diversity of braided channels is determined by various conditions of their formation, different degree of channel stability and other factors. This diversity is defined by the number, size and shape of islands, formation of islands in channel arms, composing bifurcations of the 2nd and 3rd orders, presence of floodplain branches (floodplain multi-channel), symmetry or asymmetry of braided reaches themselves, development of the bends of the branches, water discharge of the branches and distribution of runoff over them in different phases of water regime, high- and low-water years, etc. Also braided channel reaches occur when cut-off meanders are formed (incomplete meandering). On the largest rivers there are braided reaches which are characterized by the development of branches in different parts of the river valley bottom and differing in their channel and even water regime. Certain features are typical for braided reaches of wide-floodplain or incised channels, for rivers with a one-sided floodplain. As a result single, conjugated, floodplain, parallel branches, one-sided, alternate one-sided braided reaches can be either simple (for example, single or parts of conjugated formed by one island) or complex, and the latter are represented by several varieties. The identification of various morphological types, subtypes and varieties of braided channel reaches is directly connected and determines the methods of channel processes management in water economy and water transport development of rivers, construction of communications through rivers, etc.

scholarly journals Assessment of the Dnieper Alluvial Riverbed Stability Affected by Intervention Discharge Downstream of Kaniv Dam

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1104
Author(s):  
Oleksandr Obodovskyi ◽  
Michał Habel ◽  
Dawid Szatten ◽  
Zakhar Rozlach ◽  
Zygmunt Babiński ◽  
...  
Keyword(s):  
Water Discharge ◽  
Hydrological Regime ◽  
Hydroelectric Power Plant ◽  
Hydroelectric Power ◽  
Channel Stability ◽  
Catchment Scale ◽  
Channel Processes ◽  
Mean Velocity ◽  
Erosion Processes ◽  
Unconsolidated Material

Along the middle reaches of the Dnieper River in central Ukraine, braided riverbeds with many islands have developed in alluvial valleys. In the 1970s, six dams were commissioned, and respective monitoring infrastructure was installed. Riverbanks and valley floors composed of unconsolidated material have much lower bank strengths and are susceptible to fluvial erosion and bank collapse, particularly during the release of high flow volumes from hydropower dams. The regulation of the Dnieper River along a cascade of storage reservoirs caused significant changes in its active river channel and hydrological regime. In order to estimate channel stability downstream of the Kaniv reservoir, we conducted an analysis of the hydraulic conditions in terms of changes in flow velocity and propagation of waves caused by intervention water discharges from the Kaniv Hydroelectric Power Plant (HPP). In this paper, we assess the hydromorphological parameters of the studied river reach as well as the characteristics of the related erosion and deposition zones. Therefore, a monitoring framework for channel processes (MCP) downstream of the Kaniv HPP was installed. The analysis of the intervention discharge parameters was conducted based on measurements from July 2015. Channel stability was expressed by the following factors: Lohtin’s number (L), Makkaveev’s (Kc) factor of stability, and a complex index of stability (Mx) by Grishanin. This study shows that the velocity of artificial wave propagation may reach a speed of up to 74.4 km·h−1. The wave propagates for a distance of approx. 45 km within 65 min at a mean velocity of 37.4 km·h−1. The L, Kc, and Mx indicators used in this work showed that when water discharge increased (e.g., during typical peak-capacity operation), the channel becomes unstable and sediments are subject to erosion processes. The riverbed stability indicators clearly illustrate that an increase in parameter values is not dependent on the distance to the dam. The results are valuable for sustainable sediment management at catchment scale and hence, directly applicable in water management.

scholarly journals Sandstone body character, river styles, and geomorphology of the lower Eocene Willwood Formation, Bighorn Basin, Wyoming, USA

2021 ◽  
Author(s):  
Youwei WANG ◽  
Timothy Baars ◽  
Hiranya Sahoo ◽  
Joep Storms ◽  
Allard Martinius ◽  
...  
Keyword(s):  
Water Discharge ◽  
Bighorn Basin ◽  
Early Eocene ◽  
Average Width ◽  
Lower Eocene ◽  
Braided Rivers ◽  
Braided Channel ◽  
Facies Associations ◽  
Sinuous Channel ◽  
Willwood Formation

The lower Eocene Willwood Formation of the intermontane Bighorn Basin, Wyoming, USA, is an alluvial red bed succession with a sand content of ca. 20%-25%. The formation has been studied intensively for paleontology, paleoclimate, and sedimentary reconstruction. However, alluvial sandstone bodies and their corresponding river styles remain little characterized and documented. Here, efforts are made to study the characteristics and river styles of sandstone bodies through ca. 300 m of alluvial stratigraphy in the McCullough Peaks outcrop area based on the field data and a georeferenced 3-D photogrammetric model. Four channel facies associations are recognized, and they are ascribed to four river planform styles: distributary channel, massive trunk-shaped channel, braided channel, and sinuous channel, with the latter two styles being the more abundant. The channel sandstone bodies that show the character of sinuous rivers and those of braided rivers differ significantly in average thickness (6.1 m versus 9.0 m) and insignificantly in average width (on average 231 m) and paleoflow directions (on average N003). Braided-character dominated and sinuous-character dominated river styles are seen to alternate in the outcrop, while they show no spatial dependency in the 10 km2 study area. Bighorn Basin margins varied in the early Eocene, with differing tectonic, geological, and topographic characteristics. The observed mixture of river styles may be attributed to differential influences of axial and transverse river systems and/or climate change that controls water discharge and sediment load. An early Eocene geomorphologic reconstruction is constructed summarizing these new and earlier results.

Linking rivers to the rock record: Channel patterns and paleocurrent circular variance

Geology ◽  
2021 ◽  
Author(s):  
C.P. Galeazzi ◽  
R.P. Almeida ◽  
A.H. do Prado
Keyword(s):  
Water Discharge ◽  
Global Scale ◽  
Sedimentary Record ◽  
Discharge Data ◽  
Alluvial Rivers ◽  
Channel Pattern ◽  
Fluvial Deposits ◽  
Circular Variance ◽  
Rock Record ◽  
Channel Patterns

Alluvial rivers are the most important agents of sediment transport in continental basins, whose fluvial deposits enclose information related to the time when rivers were active. In order to extract the most information from fluvial deposits in the sedimentary record, it is imperative to quantify the natural variability of channel patterns at the global scale, explore what controls may influence their development, and investigate whether channel pattern information is preserved in the alluvial plains in order to develop tools for recognizing them in the sedimentary record. By surveying 361 reaches of modern alluvial rivers with available water discharge data at a global scale, we present a quantitative channel pattern classification based on sinuosity and channel count index applicable to the recognition in the rock record. A continuum of channel patterns ranging from high-sinuosity single channel to lowsinuosity multichannels is documented, along with the proportion of depositional elements in their alluvial plains and their conditions of occurrence. Preserved barforms in the alluvial plains of these rivers are used to infer and quantify paleoflow directions at the channel-belt scale and result in ranges of paleocurrent circular variance that may lead to channel pattern identification in the rock record. Data from this work indicate that the recognition of channel patterns may be used to predict paleogeographic features such as the scale of drainage basin area and discharge, slope, and annual discharge regimes.

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 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 A cusp catastrophe model for alluvial channel regime and classification of channel patterns

2014 ◽  
Vol 7 (1) ◽  
pp. 1477-1497
Author(s):  
Y. Xiao ◽  
X. J. Shao ◽  
Y. Yang
Keyword(s):  
Three Dimensional ◽  
Cusp Catastrophe ◽  
Channel Stability ◽  
Catastrophe Model ◽  
Cusp Catastrophe Model ◽  
Alluvial Channel ◽  
The Stability ◽  
Three Dimensional Coordinate ◽  
Channel Patterns ◽  
Natural Rivers

Abstract. A cusp catastrophe model for alluvial channel regime is established by selecting suitable parameters to reflect channel stability. An equation is obtained from the equilibrium state of channel regime, which is a cusp catastrophe surface in a translated three dimensional coordinate. The stability of channel patterns can be identified by such a model in a direct way, and the 2-D projection of the cusp catastrophe surface can be used to classify alluvial channel patterns. Predictions based on this model are consistent with field observations involving about 100 natural rivers. The results indicate that this method may be applied to study the regime of natural rivers and to assist decision making in river engineering.

scholarly journals Braided rivers networks dynamics: analyzing topographic data from a large flume experiment

2020 ◽  
Author(s):  
Daniel Papa ◽  
Christophe Ancey
Keyword(s):  
Single Channel ◽  
Quantitative Description ◽  
Stochastic Simulations ◽  
Braided River ◽  
Dimensionless Numbers ◽  
Braided Rivers ◽  
Braided Channel ◽  
Open Questions ◽  
Digital Elevation ◽  
Elevation Model

<p>Braided rivers are highly dynamical systems characterized by varying network-like structures even under quasi-steady conditions. Understanding their dynamics is crucial in geomorphology and river engineering (e.g., river restoration in Alpine and piedmond streams). Open questions about these dynamics include the definition and quantitative description of bed equilibrium. Here we propose to tackle this problem using a new method based on graph theory. This algorithm, called low-path allows one to extract the network structure of a braided river from its Digital Elevation Model (DEM). It is then possible to quantify and analyse the dynamics of the braided system, and not just the bed evolution, as has been done in earlier studies. To assess the dynamics and equilibrium of a braided river, we study two runs representing two distinct phases of the same braided river: the transition from a single channel to a braided river (run 1) and the equilibrium state of this river (run 2). A set of control parameters was used to characterise both runs and supplement the low-path method. We find that although a clear distinction can be made between straight channel and braided channel for both methods, it is more difficult to distinguish between transitional braided and equilibrium braided rivers. Finally we propose a set of dimensionless numbers that specify the braided network and can be used with numerical or stochastic simulations of a braided network. To illustrate their utility, we apply the Low Path method to a real Alpine braided river (the River Navisence, Wallis, Switzerland) and compare the results to our experimental data.</p>

scholarly journals Hydraulics of braided river dynamics. Insights from flume experiments

2018 ◽  
Vol 40 ◽  
pp. 02020
Author(s):  
Riccardo Vesipa ◽  
Carlo Camporeale ◽  
Luca Ridolfi
Keyword(s):  
Probability Distribution ◽  
Measurement System ◽  
Water Discharge ◽  
Flowing Water ◽  
Braided River ◽  
Flume Experiments ◽  
Braided Rivers ◽  
Bed Elevation ◽  
Active Channels ◽  
Set Up

We focus on the measurement of the topography and bathymetry in flume-models of braided rivers. To this aim, an innovative measurement system is adopted. It consists of a laser-ultrasonic sensor and can survey the bed elevation under flowing water. This measurement system was used to profile a flume transect with a frequency of 2 minutes, without stopping the water discharge. By this technique, the topography and the bathymetry of a single transect was continuously acquired in 3 braided rivers generated with the same experimental set-up. The main results are: (i) the quantification of the variability of the number of channels and number of active channels; (ii) the assessment of the probability distribution of some key hydraulic and morphodynamic parameters; and (iii) the verification of the repeatability of results obtained from flume-models of braided rivers.

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