Stream-bed armouring under known conditions of upstream sediment input

1984 ◽  
Vol 21 (9) ◽  
pp. 1061-1066 ◽  
Author(s):  
Eric J. Schiller ◽  
A. Charles Rowney
Keyword(s):  
Particle Size ◽  
Sediment Load ◽  
Experimental Tests ◽  
Direct Influence ◽  
Sediment Sources ◽  
Characteristic Parameters ◽  
Bed Forms ◽  
Sediment Input ◽  
Bed Material ◽  
Stream Bed

Experiments were conducted to assess ways in which an imposed sediment load can affect the formation and final nature of an armoured bed. A flume loaded with a quartz aggregate of known composition was subjected to various sediment-laden flows of water to produce armoured beds. Characteristic parameters of the armoured beds were then compared.In general, it was found that the final armoured bed can be significantly altered by an imposed sediment load. As the size of the input sediment increased, the amount of bed material that was eroded, the resulting particle size of the bed, and the total roughness of the bed all decreased. The formation of bed forms was very important in this process. The trends observed in these experimental tests indicate that the presence or absence of upstream sediment sources has a direct influence on the resulting armoured layer.

scholarly journals Re-suspension of bed sediment in a small stream – results from two flushing experiments

2014 ◽  
Vol 18 (3) ◽  
pp. 1043-1052 ◽  
Author(s):  
A. Eder ◽  
M. Exner-Kittridge ◽  
P. Strauss ◽  
G. Blöschl
Keyword(s):  
Sediment Load ◽  
Free Water ◽  
High Temporal Resolution ◽  
Sediment Sources ◽  
Small Stream ◽  
Bed Sediments ◽  
Small Watersheds ◽  
Wave Celerity ◽  
Total Sediment ◽  
Stream Bed

Abstract. Streams draining small watersheds often exhibit multiple peaking sedigraphs associated with single peaking hydrographs. The process reasons of the multiple sediment peaks are not fully understood but they may be related to the activation of different sediment sources such as the stream bed itself, where deposited sediments from previous events may be available for resuspension. To understand resuspension of stream bed sediments at the reach scale we artificially flooded the small stream of the HOAL Petzenkirchen catchment in Austria by pumping sediment-free water into the stream. Two short floods were produced and flow, sediment and bromide concentrations were measured at three sites with high temporal resolution. Hydrologically, the two flood events were almost identical. The peak flows decreased from 57 to 7.9 L s−1 and the flow volumes decreased from 17 to 11.3 m2 along the 590 m reach of the stream. However, a considerably smaller sediment load was resuspended and transported during the second flood due to depletion of stream bed sediments. The exception was the middle section of the stream, where more sediment was transported during the second flood event which can be explained by differences between flow velocity and wave celerity and the resulting displacement of sediments within the stream. The results indicate that the first peak of the sedigraphs of natural events in this stream is indeed caused by the resuspension of stream bed sediments, accounting for up to six percent of the total sediment load depending on total flow volume.

A review on share of river bank erosion to the total sediment load with increasing catchment size

2021 ◽  
Author(s):  
Ghulam Abbas ◽  
Seifeddine Jomaa ◽  
Michael Rode
Keyword(s):  
Sediment Load ◽  
Bank Erosion ◽  
Surface Erosion ◽  
Sediment Sources ◽  
Catchment Scale ◽  
River Bank ◽  
River Bank Erosion ◽  
Wide Range ◽  
Catchment Size ◽  
Total Sediment

<p>Information on the share of river bank erosion to the total sediment load at catchment scale by using the fingerprinting approach is important to address our knowledge of erosion processes to better target soil erosion control measures. In particular, river bank erosion is affected by many factors such as spatial and temporal variables and is difficult to quantify the relationship of the share of bank erosion to catchment size and upland erosion rate without extensive fieldwork and data analysis. Potential tracers including geochemical, fallout radionuclides, bulk and compound-specific stable isotopes, and magnetic properties have been used, often in combination with sediment source apportionment. In this worldwide review, the global dataset for percent share of river bank and surface erosion using fingerprinting approach was collected to establish the significance of catchment size and other physical controls on river bank erosion. Google Scholar and Web of Science were used to review research articles that included river bank/subsurface as one of the sediment sources in the study areas. This database showed that the UK (n = 84), USA (n = 14) and Brazil (n = 10) had the highest number of catchments, followed by Iran (n = 4), Southern Zambia (n = 1), Australia (n = 1), Spain (n = 1), Mongolia (n = 1) and Burkina Faso (n = 1) ranging in size from 0.31 to 15000 km<sup>2</sup>, predominately agriculture. Based on published studies, there is a clear shift of sediment sources from surface erosion to river bank erosion with increasing catchment size. The results show the wide range of relative contributions of surface and river bank sources to the catchment sediment yield around the globe. There are a number of catchments with river bank contribution exceeding 25% and surface contribution exceeding 90% of total sediment loss. This diversity highlights the many factors that influence river bank erosion. In addition to the wide range, sediment source contribution in the range 1-25% from river bank is generally representative around the World. We recommend that long term monitoring of sediment load and surface and river bank sources at nested sites within a catchment are indispensable. Furthermore, limited information on the share of sources often makes it difficult to target mitigation measures reducing sediment loads at the catchment scale.</p><p><strong>Keywords: </strong>Sediment load, catchment size, fingerprinting approach, river bank share</p>

Superplastic Materials Characterisation Based on Free-Bulge Tests

2020 ◽  
Vol 306 ◽  
pp. 15-22
Author(s):  
Luis García-Barrachina ◽  
A.J. Gámez
Keyword(s):  
Parameter Estimation ◽  
Tensile Test ◽  
Apparent Viscosity ◽  
Experimental Tests ◽  
Characteristic Parameters ◽  
Forming Process ◽  
Viscosity Function ◽  
Computer Aided ◽  
Fluid Behaviour ◽  
Good Agreement

A new characterisation method based on free-bulge tests is proposed to find the characteristic parameters of the strainstress relation in superplastic alloys. The method is applied to experimental tests found in the literature and to new adhoc tests performed on aluminium, magnesium and titanium alloys. The parameters are then compared to independent values obtained from tensile test and computer-aided simulations. The characterisation of the material is evaluated as an apparent viscosity function of the strain-rate and is extracted from the height evolution at the apex dome during the forming process. Results show a good agreement between parameter estimation using this method and independent values. Moreover, this characterisation method exposes the non-newtonian fluid behaviour of these materials during superplastic processes known as shear-thinning or pseudoplasticity.

Simulation Method of Particle Size Scale for Fine Sand Model

2014 ◽  
Vol 580-583 ◽  
pp. 1878-1882
Author(s):  
Wan Li Liu ◽  
Xiao Fei Liu ◽  
Pei Jiu Yue
Keyword(s):  
Particle Size ◽  
Fine Sand ◽  
Simulation Method ◽  
Size Scale ◽  
Sediment Movement ◽  
Design Basis ◽  
Median Particle ◽  
Flow Intensity ◽  
Material Grain Size ◽  
Bed Material

In sediment movable bed model, the basic similar conditions include the flow movement similar and the sediment movement similar. In water flow movement similar conditions, the velocity scale of the Freund's similarity and resistance similarity is inconsistency, and the flow resistance is the function of bed material grain size and flow intensity. In sediment movement similar, the particle size scale forms are not consistent too, and they are also related to the flow conditions, so the sediment partial size scale is difficult to determine. According to the research, the similar conditions can be focused on primary and secondary one, and put the primary one as the design basis. In view of the waterway regulation, the regulation flow discharge should be the design basis, others allowed a certain deviation; In the straight reach, resistance similarity should be the design basis, Freund's similarity allowed a certain deviation; In the bend reach, the Freund's similarity and resistance similarity should be simultaneously satisfied; For the bed load model, the incipient motion should meet similarity condition; The suspended sediment model should meet the sediment suspension similarity; For the non-uniform sediment, median particle size should be the design basis. According to the above principles, the sediment particle size scale can be determined.

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