Two experimental sediment traps: operation and solids characteristics

1996 ◽  
Vol 33 (9) ◽  
pp. 155-162 ◽  
Author(s):  
Jean-Luc Bertrand-Krajewski ◽  
Hervé Madiec ◽  
Olivier Moine
Keyword(s):  
Grain Size ◽  
Field Experiments ◽  
Sediment Traps ◽  
Bed Load ◽  
Storm Events ◽  
Organic Fraction ◽  
Inlet Pipe ◽  
Median Axis ◽  
South West ◽  
Interesting Alternative

Specific sediment traps for solids transported as bed load during storm events could be an interesting alternative to usual grit chambers. Two field experiments have been carried out in Bordeaux (south-west of France) in 1993 and 1994 to characterise the solids caught in the traps and to assess the sediment trap efficiency. These two sites have been chosen because it was easy to transform the existing usual grit chambers with a set of boxes used as sediment traps. The mass of trapped solids is well correlated with the rainfall height, for rainfalls of less than 50 mm. For greater rainfalls, the experimental sediment traps were too small to catch all solids. The efficiency of the sediment traps located at the grit chamber inlet side is assessed at about 70-80% in mass. Only 20-30% of solids are trapped at the outlet side. The efficiency decreases rapidly for the traps that are not in alignment with the median axis of the inlet pipe. The grain size distribution of the trapped solids is very characteristic: the d10, d50 and d90 values decrease when the traps are farther away from the median axis of the inlet pipe. This distribution of the trapped solids is due to the enlargement of the grit chamber which leads to a decrease of the flow velocity. The organic fraction increases when the d50 decreases: the finer the particles, the more organic the fractions.

Improved growth and yield of Faba beans (Vicia faba cv. Fiord) by inoculation with strains of Rhizobium leguminosarum biovar. viciae in acid soils in south west Victoria

1994 ◽  
Vol 45 (3) ◽  
pp. 613 ◽  
Author(s):  
JM Carter ◽  
WK Gardner ◽  
AH Gibson
Keyword(s):  
Vicia Faba ◽  
Rhizobium Leguminosarum ◽  
Field Experiments ◽  
Natural Populations ◽  
Acid Soils ◽  
Growth And Yield ◽  
Nitrogen Accumulation ◽  
Commercial Strain ◽  
South West ◽  
Faba Beans

The response of faba beans (Vicia faba L. cv. Fiord) to seed inoculation with eight strains of Rhizobium leguminosarum biovar. viciae was examined in field experiments at six sites on acid soils in south-west Victoria. At two of the sites, two additional strains were examined, and in 1988, 14 strains were examined at one site. Very low natural populations of R. leguminosarum bv. viciae were found at the experimental sites. Most strains resulted in improved early nodulation and increased grain yield at all sites, when compared to inoculation with the commercial strain of rhizobia (SU391). Plant dry matter production and nitrogen accumulation in the plant shoot tissue was also increased at one site during the flowering period by some strains. Large visual differences between plots inoculated with SU391 and other strains were evident at most sites. Most uninoculated treatments were not nodulated and yielded very poorly. Treatments inoculated with the strain SU391 performed similarly to the uninoculated treatments.

scholarly journals A method for detecting the presence of organic fraction in nucleation mode sized particles

2005 ◽  
Vol 5 (12) ◽  
pp. 3277-3287 ◽  
Author(s):  
P. Vaattovaara ◽  
M. Räsänen ◽  
T. Kühn ◽  
J. Joutsensaari ◽  
A. Laaksonen
Keyword(s):  
Sulfuric Acid ◽  
Field Experiments ◽  
Inorganic Compounds ◽  
Particle Diameter ◽  
Ethanol Vapor ◽  
Organic Fraction ◽  
Saturation Ratio ◽  
Nucleation Mode ◽  
Atmospheric Nucleation ◽  
20 Nm

Abstract. New particle formation and growth has a very important role in many climate processes. However, the overall knowlegde of the chemical composition of atmospheric nucleation mode (particle diameter, d<20 nm) and the lower end of Aitken mode particles (d≤50 nm) is still insufficient. In this work, we have applied the UFO-TDMA (ultrafine organic tandem differential mobility analyzer) method to shed light on the presence of an organic fraction in the nucleation mode size class in different atmospheric environments. The basic principle of the organic fraction detection is based on our laboratory UFO-TDMA measurements with organic and inorganic compounds. Our laboratory measurements indicate that the usefulness of the UFO-TDMA in the field experiments would arise especially from the fact that atmospherically the most relevant inorganic compounds do not grow in subsaturated ethanol vapor, when particle size is 10 nm in diameter and saturation ratio is about 86% or below it. Furthermore, internally mixed particles composed of ammonium bisulfate and sulfuric acid with sulfuric acid mass fraction ≤33% show no growth at 85% saturation ratio. In contrast, 10 nm particles composed of various oxidized organic compounds of atmospheric relevance are able to grow in those conditions. These discoveries indicate that it is possible to detect the presence of organics in atmospheric nucleation mode sized particles using the UFO-TDMA method. In the future, the UFO-TDMA is expected to be an important aid to describe the composition of atmospheric newly-formed particles.

Measuring Bed Load Transport Rates by Grain-Size Fraction Using the Swiss Plate Geophone Signal at the Erlenbach

2016 ◽  
Vol 142 (5) ◽  
pp. 04016003 ◽  
Author(s):  
Carlos R. Wyss ◽  
Dieter Rickenmann ◽  
Bruno Fritschi ◽  
Jens M. Turowski ◽  
Volker Weitbrecht ◽  
...  
Keyword(s):  
Grain Size ◽  
Size Fraction ◽  
Bed Load ◽  
Load Transport ◽  
Bed Load Transport

Yield response of restricted-tillering wheat to transient waterlogging on duplex soils

2003 ◽  
Vol 54 (10) ◽  
pp. 957 ◽  
Author(s):  
A. G. Condon ◽  
F. Giunta
Keyword(s):  
Grain Size ◽  
Biomass Production ◽  
Wheat Yield ◽  
Relative Yield ◽  
Field Trials ◽  
Growth And Yield ◽  
Yield Response ◽  
South West ◽  
Relative Extent ◽  
Before And After

Transient waterlogging during winter and spring reduces wheat yield in many parts of southern Australia. Yield reductions from waterlogging are associated with reduced production and survival of tillers, fewer and smaller fertile tillers, and smaller grain size. Under favourable conditions, wheats that have the tiller-inhibition ('tin') gene produce a lower total number of tillers but a higher proportion of large, productive tillers and larger grains than wheats without this gene. These characteristics of restricted-tillering wheat may contribute to improved yield under transient waterlogging. We compared the growth and yield of the commercial variety Bodallin and 2 Bodallin backcross derivatives containing the 'tin' gene in 8 field trials grown on shallow, duplex soils in 1995 and 1996 at 3 locations in the south-west of Western Australia. Trials were sown at standard (1995) and standard and high (1996) seeding rates. Trial-mean yield ranged from 0.5 to 4.7 t/ha, depending on the occurrence and severity of waterlogging before anthesis and of soil water deficit before and after anthesis. Grain yield of the restricted-tillering (RT) lines averaged only c. 80% of Bodallin. At all sites and seeding rates the RT lines had fewer spikes per m2 (45% fewer, on average) but averaged 44% more grains per spike. In 1996 only, grain weight of the RT lines was 6% greater than of Bodallin. There was no evidence that the relative yield of the RT lines was greater at waterlogged sites than at other sites. Waterlogging reduced the number of fertile spikes of RT lines and of Bodallin to the same relative extent and differences in grains per spike and grain size had little effect on relative yields. Even though harvest index of the RT lines was slightly elevated in some environments, biomass production of the RT lines was low in all environments. We conclude that wheats with the 'tin' gene are unlikely to have a yield advantage under transient waterlogging unless their biomass production can match that of more freely tillering wheats.

Numerical modelling of bed load sediment traps in sewer systems by density currents

1999 ◽  
Vol 39 (9) ◽  
pp. 153-160 ◽  
Author(s):  
F. Schmitt ◽  
V. Milisic ◽  
J.-L. Bertrand-Krajewski ◽  
D. Laplace ◽  
G. Chebbo
Keyword(s):  
Sediment Trap ◽  
Sediment Traps ◽  
Bed Load ◽  
Density Currents ◽  
Solid Concentration ◽  
Two Phase ◽  
Trap Design ◽  
Continuous Layer ◽  
Sewer Systems ◽  
Load Sediment

A model with density currents has been developed and tested to simulate bed load sediment traps. In this model, the bed load layer over the pipe invert is considered as a continuous layer characterised by a density and a viscosity which depends on the solid concentration. A set of equations has been established that describes the trapping of the bed load material as the dynamics of two non-miscible fluids over and in the bed load sediment trap. The Fluent package has been used and adapted to solve the equations of the model. The VOF method (Volume Of Fluid) has been chosen to solve the two phase approach according to a Euler-Euler scheme. Several series of simulations have been carried out in order to assess the influence of the slot position and trap design on efficiency. The results obtained agree with previous empirical findings, and allow confirmation (in a more reliable manner than before) that the best sediment trap design involves a centrally-placed slot with the two plates covering the trap reservoir placed at the same height as one another.

scholarly journals Design optimization of permeable sediment traps for fluvial bed load transport

2018 ◽  
Vol 40 ◽  
pp. 03009 ◽  
Author(s):  
Anita Roth ◽  
Mona Jafarnejad ◽  
Sebastian Schwindt ◽  
Anton Schleiss
Keyword(s):  
Sediment Trap ◽  
Sediment Traps ◽  
Sediment Supply ◽  
Bed Load ◽  
Hydraulic Control ◽  
Check Dam ◽  
Sediment Retention ◽  
Existing Structures ◽  
Load Transport ◽  
Set Up

Sediment traps are crucial elements for flood protection in mountain rivers with high sediment transport capacity. Existing structures often interrupt the channel connectivity. Ideally, a sediment trap should be permeable for bed load during non-hazardous floods and ensure sediment retention during hazardous discharges. A new sediment trap concept, fulfilling these requirements was recently developed and tested in a laboratory flume. A guiding channel trough the deposition area is combined with a slot check dam having an upstream bar screen with bottom clearance. This study aims to validate the proposed concept with a finer sediment mixture on an experimental set-up. Furthermore, we provide improved recommendations for bar screen design regarding minimal bar spacing and the range of applicable clearance heights. Optimal bar spacing and clearance heights of the bar screen are determined through individual tests of the bar screen with steady discharges and varying sediment supply intensity. The best performing bar screen configuration is subsequently tested in combination with a slot check dam using a flood hydrograph to simulate the influence of quasi-unsteady discharge. The proposed concept corresponds to a combined mechanical-hydraulic control and works well for a large range of grain sizes, if the bar screen is correctly adapted.

scholarly journals Reduced Tillage Impacts on Pumpkin Yield, Weed Pressure, Soil Moisture, and Soil Erosion

HortScience ◽  
2016 ◽  
Vol 51 (12) ◽  
pp. 1524-1528 ◽  
Author(s):  
Megan E. O’Rourke ◽  
Jessica Petersen
Keyword(s):  
Soil Moisture ◽  
Soil Erosion ◽  
Weed Control ◽  
Field Experiments ◽  
Production Systems ◽  
Conservation Tillage ◽  
Fruit Weight ◽  
Storm Events ◽  
No Till ◽  
Trade Offs

Conservation tillage has the potential to decrease the environmental footprint of pumpkin production, but possible trade-offs with yield are not well understood. This study experimentally tested the effects of three cultivation techniques (conventional-till, strip-till, and no-till) on pumpkin production, weed pressure, soil moisture, and soil erosion. Randomized complete block field experiments were conducted on Cucurbita pepo L. ‘Gladiator’ pumpkins in 2014 and 2015. Overall yields were higher in 2015, averaging 45.2 t·ha−1, compared with 37.4 t·ha−1 in 2014. In 2014, pumpkin yields were similar across tillage treatments. In 2015, the average fruit weight of no-till pumpkins was significantly greater than strip-till and conventional-till pumpkins, which corresponded to a marginally significant 13% and 22% yield increase, respectively (P = 0.11). Weed control was variable between years, especially in the strip-till treatment. Soil moisture was consistently highest in the no-till treatment in both years of study. Conventional-till pumpkin plots lost ≈9 times more soil than the two conservation tilled treatments during simulated storm events. The 2015 yield advantage of no-till pumpkins seems related to both high soil moisture retention and weed control. Research results suggest that no-till and strip-till pumpkin production systems yield at least as well as conventional-till systems with the advantage of reducing soil erosion during extreme rains.

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