scholarly journals Predicting river channel pattern based on stream power, bed material and bank strength

2020 ◽  
pp. 030913332094883
Author(s):  
Jasper Candel ◽  
Maarten Kleinhans ◽  
Bart Makaske ◽  
Jakob Wallinga
Keyword(s):  
Clay Fraction ◽  
Stream Power ◽  
Channel Pattern ◽  
Meandering Channel ◽  
Approximate Boundary Conditions ◽  
Channel Slope ◽  
Channel Patterns ◽  
Bed Material ◽  
Bank Strength ◽  
Independent Parameters

Rivers exhibit a wide variety of channel patterns, and predicting changes in channel pattern is important in order to foresee river responses to climate change and river restoration. Many discriminators have been developed to define approximate boundary conditions for different channel patterns, based on channel-pattern-controlling parameters such as discharge and valley gradient. However, presently available discriminators have two main shortcomings. First, they perform poorly for rivers with cohesive, relatively erosion-resistant banks. For this subset, discriminators tend to indicate an actively meandering channel pattern, whereas the river morphology and dynamics show that many of these rivers should be classified as laterally stable. Second, channel pattern discriminators are often used to predict channel patterns, which is only valid when parameters are used that are independent of actual channel pattern. This condition is often not met, as many discriminators use the channel slope or width–depth ratio of the channel as input. To resolve both shortcomings, we first propose an additional class of rivers with scroll bars and tortuous channel patterns, which have an inhibited mobility due to their self-formed cohesive deposits. Second, we compare frequently used empirical and mechanistic channel pattern discriminators, taking into account the success in predicting channel pattern and the independence of causal factors used. Thirdly, we present a novel channel pattern discriminator and predictor that includes the effect of a cohesive floodplain, using the average silt-plus-clay fraction of the river banks as proxy. We show that this new predictor outperforms previously used empirical and mechanistic approaches, and successfully predicts channel pattern for 87% of the rivers from a dataset of 70. This new predictor is widely applicable, as it is relatively simple and based on easily obtainable, and mostly independent, parameters.

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 Freshwater Mussel Bed Habitat in an Alluvial Sand-Bed-Material-Dominated Large River: A Core Flow Sediment Refugium?

Diversity ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 174
Author(s):  
Alan D. Christian ◽  
Andrew J. Peck ◽  
Ryan Allen ◽  
Raven Lawson ◽  
Waylon Edwards ◽  
...  
Keyword(s):  
Flow Direction ◽  
Freshwater Mussel ◽  
Physical Habitat ◽  
Stream Power ◽  
Mussel Bed ◽  
Mean Velocity ◽  
Core Flow ◽  
White River ◽  
Bed Material ◽  
Mussel Habitat

Habitat degradation, organismal needs, and other effects influencing freshwater mussel declines have been subject to intense focus by conservationists for the last thirty plus years. While researchers have studied the physical habitat requirements and needs of mussels in small- to medium-sized rivers with variable levels of success, less research has been conducted on mussel habitat in larger non-wadeable rivers, especially at the reach scale, where core flow environmental conditions provide and maintain habitat for freshwater mussels. We designed a quasi-experimental observational field study to examine seven hydrologic energy and material variables laterally and longitudinally at Current and Extirpated mussel bed habitat reaches in lower White River, Arkansas, a large non-wadeable, sand-bed-material-dominated river. As expected, lateral and longitudinal hydrologic variable differences were identified within a reach. Mean velocity, bed velocity, the Froude number, and stream power were all significantly lower at Current mussel bed habitat stations within a sampling reach. Energy regime differences in shear stress and, marginally, stream power were higher at Extirpated mussel bed habitat reaches. Several factors emerged as important to mussel habitat in the White River. First, bed velocity warrants further exploration in terms of both flow strength and flow direction. Second, bedload appears to be the primary contributor to mussel habitat but requires additional exploration within the context of core and secondary flow pathway interactions. The combined empirical evidence from our study supports the flow refugium concept identified for mussel habitats in smaller systems but expands the concept to large non-wadeable streams and includes reach-scale refuge from sediment transport conditions.

Minimum stream power and river channel patterns

1979 ◽  
Vol 41 (3-4) ◽  
pp. 303-327 ◽  
Author(s):  
Howard H. Chang
Keyword(s):  
River Channel ◽  
Stream Power ◽  
Channel Patterns

scholarly journals ANALISIS TATANIAGA KOPRA DI DESA BALOBONE KECAMATAN MAWASANGKA KABUPATEN BUTON TENGAH

2019 ◽  
Vol 3 (2) ◽  
pp. 73-92
Author(s):  
Waode Alzarliani
Keyword(s):  
Marketing Channel ◽  
Sampling Procedure ◽  
Marketing Channels ◽  
Snowball Sampling ◽  
Marketing System ◽  
Channel Pattern ◽  
Channel Patterns ◽  
The Cost ◽  
Short Time ◽  
Marketing Margins

This research was conducted in Balobone Village, Mawasangka Sub-district, Central Buton Regency. Coconut farmers in Balobone village have problems, in addition to the low quality of copra as well as price fluctuations in a short time often occur in copra marketing so that it affects the marketing efficiency that is formed. For this reason, a comprehensive assessment of the most efficient copra marketing system needs to be carried out, so that it can provide a proportional income contribution for farmers. The objectives of this study are: (1) Knowing copra marketing channels in Balobone Village; (2) Knowing the number of costs, margins and profits received by each marketing institution involved in copra marketing in Balobone Village; (3) Analyzing copra market performance in Balobone Village through analysis of marketing margins and producer share. The sampling procedure is carried out in an institutional approach with a snowball sampling method with the amount adjusted to field conditions and research analysis needs. Marketing channel analysis is done descriptively qualitatively to see the pattern of marketing channels formed during the copra drainage process from producer farmers to exporter traders. The conclusions of the research are (1) Farmers in marketing copra produced through 2 patterns of marketing channels, namely: a. The pattern I Marketing Channels: Inter-island Traders Surabaya Big Surabaya Traders. (2) The result of Analysis of Marketing Margin 1 received by traders shows that the marketing margin of the village collecting trader is IDR 600/Kg, costs IDR 350/Kg, Profits IDR 250/Kg, while the marketing margin of the big traders in Baubau Town is IDR 3,700/kg, with the cost IDR 1,354.5/kg, the profit received is IDR 2,543.5 / kg. Pattern 2 marketing margin received by inter-island traders is IDR 4,300, with a total cost of IDR 1,354.5/Kg, with a profit of IDR 2,945.5/Kg; (3) The percentage of the price received by farmers from each of the marketing channels I patterns is 53% and the marketing channel pattern 2 is 53. Thus, the copra marketing system of the 2 marketing channel patterns formed in Balobone Village is efficient. Farmers, Village Traders, Large Village Traders, Large Traders I (Exporters); (b) Marketing Channel Pattern II: Farmers.   Keywords: Copra, marketing margins, marketing channels

scholarly journals Empirical Studies in Alluvial Streams

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Levent Yilmaz
Keyword(s):  
Single Channel ◽  
Empirical Studies ◽  
Laboratory Data ◽  
Fine Sediments ◽  
Channel Interaction ◽  
Variable Curvature ◽  
Alluvial Channel ◽  
Channel Patterns ◽  
Bed Material ◽  
River Meandering

Meander flow takes place in one single channel which oscillates more orless regularly with amplitudes that tend to increase with time. Meandersare found in beds of fine sediments with gentle slopes. In this study, effortwill be made to investigate meanders’ turbulent boundary layer and toimprove the present knowledge about the river meandering phenomena. Itis assumed that the development of the perturbations which develop intomeanders or braids, is longer than the width of the channel. Interaction between the flow and mobile boundaries produces channel patterns which areclassified as meandering or braided. It is therefore long compared with theripples or dunes which cover the bed of such a channel and whose wavelength is shorter than the width of the channel. The variation of resistance toflow and rate of transport of bed material with velocity are discussed brieflyand taken into account. Meander flow and meander shear stress distribution of the channel are described. The basis is a steady, two-dimensionalmodel of flow in an alluvial channel with variable curvature. The meanderdevelopment is described by forcing a travelling, small-amplitude channelalignment wave on the system, and determining the growth characteristicsof the wave. Laboratory data are used to verify the formulas.

scholarly journals Effect of riparian vegetation roots on development of meander bends in Tarim River, Northwest China

2018 ◽  
Vol 40 ◽  
pp. 02029
Author(s):  
Guo-An Yu ◽  
Zhiwei Li ◽  
He Qing Huang ◽  
Weiwei Yao
Keyword(s):  
Phragmites Australis ◽  
Riparian Vegetation ◽  
Clay Content ◽  
Fine Sand ◽  
Northwest China ◽  
Necessary Condition ◽  
Tarim River ◽  
River Bank ◽  
Meandering Channel ◽  
Bank Strength

Meandering channel with distorted bends develops along the Tarim River, the longest dryland river in China. The river bank and bed is majorly composed of coarse silt and fine sand and almost none clay content, making the bank strength very low. The development of meander bend in such environment hence is somehow irrational. We preliminarily investigate the effects of riparian vegetation root on bend development in this region through examining the root cohesion and its enhancement on bank stability. In-situ measurements and sampling of roots from local typical riparian vegetation (i.e., populous, Tamarix, and Phragmites Australis) were conducted to obtain root parameters like diameter and root area ratio. Local bend curvature corresponding to sampling sites are also obtained. BSTEM model is used to quantitatively estimate the effects of different root conditions on improving channel bank strength. Four vegetation root scenarios were modelled, i.e., tree (populous), shrub (Tamarix), grass (Phragmites Australis) and no root. The results show that root supplies effective cohesive reinforcement for the channel bank and enhances the bank safety factors (Fs). Riparian vegetation should be a necessary condition for development of meandering channel in Tarim River.

Influences of Flow Discharge Processes on Morphological Evolutions in an Experimental Channel: A 3-D Numerical Study

2013 ◽  
Vol 353-356 ◽  
pp. 2515-2519
Author(s):  
Dong Dong Jia ◽  
Xue Jun Shao ◽  
Xing Nong Zhang ◽  
Chang Ying Chen
Keyword(s):  
Flow Condition ◽  
Numerical Study ◽  
Morphological Changes ◽  
Discharge Process ◽  
Alluvial Rivers ◽  
Meandering Channel ◽  
Experimental Channel ◽  
Unsteady Flow Condition ◽  
Flow And Sediment Transport ◽  
Channel Patterns

The discharge process influences the morphological evolutions of alluvial rivers, even the channel pattern evolutions. The impacts of discharge processes on morphological evolutions in an experimental channel were investigated by a 3-D mathematical model, in which turbulence flow and sediment transport as well as bank erosion were modeling. The simulated results demonstrated that the discharge process had significant effects on morphological changes. Planfrom evolution in the period with large discharge was much more notable than that with small discharge. Different discharge processes may lead to different channel patterns. A single meandering channel was formed under steady flow condition. A braided channel was observed with unsteady flow condition.

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