Variations of bed surface sediment size in a channel bend

1997 ◽  
Vol 99 (1-4) ◽  
pp. 81-88 ◽  
Author(s):  
Chin-Lien Yen ◽  
Yan-Lang Lin
Keyword(s):  
Surface Sediment ◽  
Sediment Size ◽  
Channel Bend

Effect of lift on bed‐surface sediment size distribution in channel bend

2006 ◽  
Vol 29 (4) ◽  
pp. 565-579 ◽  
Author(s):  
Jiun‐Huei Jang ◽  
Hsin‐Ya Ho ◽  
Chin‐Lien Yen
Keyword(s):  
Size Distribution ◽  
Surface Sediment ◽  
Sediment Size ◽  
Channel Bend

scholarly journals Effects of Spur Dyke’s Orientation on Bed Variation in Channel Bend

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Mohammad Athar ◽  
Talib Mansoor ◽  
Nishank Aggarwal
Keyword(s):  
Angular Displacement ◽  
Velocity Shear ◽  
Bridge Piers ◽  
Geometrical Parameters ◽  
Meandering Channel ◽  
Sediment Size ◽  
Channel Bend ◽  
Outer Bank ◽  
Main Emphasis ◽  
Present Thesis

Spur dykes also known as Groynes are often used to either divert or attract the flow from the main structure to safeguard their life. Those structures may be bridge piers, abutments or any similar hydraulics structures. Spur dykes are also used to save the cutting of banks on concave side of stream. Lots of work have been done in recent past on spur dykes by many investigators in which various hydraulic and geometrical parameters of spur dykes such as discharge, sediment size, flow velocity, shear stress, spur dykes shape, size and submergence etc. are studied in detail. But mostly all the studies were pointed out in straight open channels. Very few studies were done in curved channel and only their similar effects were studied. In present thesis main emphasis is given to study the effect of orientation and location of spur dykes in meandering channel on the bed of downstream side. In the present study experimental work has been carried out in 80° bend and constant discharge (Q = 4.5 l/s) is allowed to pass in channel without spur dyke. It is found that maximum scouring occurs at angular displacement θ = 60° to 80° in the vicinity of outer bank. To minimize this scouring, spur dyke has been installed at angular displacement θ = 20°, 40° & 60° by changing the dyke angle α = 60°, 90° & 120° respectively. It is found that scouring at θ = 60° is reduced by installing spur dyke at angular displacement θ = 40° which is oriented at α = 60° and scouring at θ = 80° is reduced by installing spur dyke at angular displacement θ = 60° which is oriented at α = 60°.

Study on the Seasonal Variation of Surface Sediment Composition in Estuaries

1988 ◽  
Vol 20 (6-7) ◽  
pp. 123-132
Author(s):  
O. Kawara
Keyword(s):  
Particle Size ◽  
Seasonal Variation ◽  
Surface Sediment ◽  
Seasonal Variations ◽  
River Estuary ◽  
Water Runoff ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Sediment Composition ◽  
Sediment Size

The purpose of this study, as the first step toward clarifying the pollutant transport mechanism of sediments, is to clarify the characteristics of the seasonal changes of surface sediment composition in estuaries based on observation. Remarkable seasonal variations are found in the particle size distributions and the concentrations of the constituents of the surface sediments, though the patterns of the variations are different in each estuary observed. The seasonal variations of the concentrations show good correspondence to those of the particle size distributions. One cause of the seasonal variation is the variation of river discharges. When the sediment size in the Asahi River estuary, Okayama prefecture, became finer, the fresh water inflow to the estuary was about 2.5-3.5 times as much as ordinary water runoff (100-150m3/s) and the change was completed in about 10 days. On the other hand, the change to coarser sediment was completed in a day, by the inflow of over 400m3/s.

THE ABUNDANCE OF RECENT FORAMINIFERA IN SURFACE SEDIMENT OF AMBON BAY

2010 ◽  
Vol 2 (1) ◽  
Author(s):  
Suhartati M. Natsir
Keyword(s):  
Surface Sediment ◽  
Benthic Foraminifera ◽  
Sea Water ◽  
Planktonic Foraminifera ◽  
Sediment Characteristic ◽  
Abundance And Distribution

Foraminifera are generally live in sea water with various sizes. These organisms consist of planktonic and benthic foraminifera. Geological activity on plutonic and volcanic with vomiting magma is transpiring on, and then affects sedimentation and foraminiferal abundance of Ambon Bay. The study was determined to study the abundance and distribution of foraminifera based on the sediment characteristic of Ambon Bay. Sample collected in 2007 of Ambon Bay showed that only 29 samples of 50 samples containing foraminifera. The collected sediments have 86 species of foraminifera, consisting 61 species of benthic foraminifera and 25 species of planktonic foraminifera. The dominant benthic foraminifera in the surface sediment of Ambon bay were Amphistegina lessonii, Ammoniabeccarii,Elphidium craticulatum,Operculina ammonoides and Quinqueloculina parkery. The planktonic foraminifera that were frequently collected from the bay were Globorotalia tumida, Globoquadrina pseudofoliata, Globigerinoides pseudofoliata, Globigerinoides cyclostomus dan Pulleniatina finalis. Generally, the species dwelled as abundant on substrate sand, whereas the areas within substrate mud have no foraminifera lie on them. Keywords: Foraminifera, Abundance, Sediment, Ambon Bay

Particle Size Effects on Concentration of Metals in Lake Erie Bottom Sediments

1984 ◽  
Vol 19 (1) ◽  
pp. 27-36 ◽  
Author(s):  
Alena Mudroch
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Clay Minerals ◽  
Surface Sediment ◽  
Size Effects ◽  
Lake Erie ◽  
Size Fraction ◽  
Mineralogical Composition ◽  
Major Elements ◽  
Sediment Samples

Abstract Surface sediment samples obtained at the offshore and nearshore area of Lake Erie were separated into eight different size fractions ranging from <2 µm to 250 µm. The concentration of major elements (Si, Al, Ca, Mg, K, Na, Fe, Mn and P), metals (Zn, Cu, Cr, Ni, V, Co and Pb) and organic matter was determined together with the mineralogical composition and morphology of the particles in each size fraction. The distribution of the metals in the offshore sediment was bimodal with the majority of the metals divided between the 63 to 250 um size fraction which also contained the highest concentration of organic matter (about 20%) and the <4 µm fraction containing up to 60% of clay minerals. However, the metals in the nearshore sediment were associated mainly with the clay minerals.

Design options for self-cleansing storm sewers

1996 ◽  
Vol 33 (9) ◽  
pp. 215-220 ◽  
Author(s):  
Chandramouli Nalluri ◽  
Aminuddin Ab. Ghani
Keyword(s):  
Cohesive Sediments ◽  
Stress Criterion ◽  
Sediment Bed ◽  
Sediment Size ◽  
Codes Of Practice ◽  
Design Charts ◽  
Design Options ◽  
Minimum Velocity ◽  
Limited Depth ◽  
Storm Sewers

A list of available codes of practice for self-cleansing sewers is presented and a review of appraisals of minimum velocity criterion is summarised. Comparisons of newly developed “minimum velocity” criteria and “minimum shear stress” criterion are presented. Some design charts are also given. These charts are applicable to non-cohesive sediments (typically storm sewers). It appears that sediment size and concentration need to be taken into account, and that a limited depth of sediment bed is recommended for large pipes (diameters > 1000 mm) to maximise their transport capacity.

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