Aquatic weed growth and flow resistance: Influence on the relationship between discharge and stage over a 25 year river gauging station record

1994 ◽  
Vol 8 (1) ◽  
pp. 63-73 ◽  
Author(s):  
Angela M. Gurnell ◽  
Peter Midgley
Keyword(s):  
Flow Resistance ◽  
Aquatic Weed ◽  
Weed Growth ◽  
The Relationship ◽  
Station Record ◽  
Gauging Station

scholarly journals Evaluating the Effects of Sediment Transport on Pipe Flow Resistance

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2091
Author(s):  
Vito Ferro ◽  
Alessio Nicosia
Keyword(s):  
Velocity Profile ◽  
Pipe Flow ◽  
Power Distribution ◽  
Flow Resistance ◽  
Unit Length ◽  
Particle Diameter ◽  
Self Similarity ◽  
Sediment Size ◽  
The Mean ◽  
The Relationship

In this paper, the applicability of a theoretical flow resistance law to sediment-laden flow in pipes is tested. At first, the incomplete self-similarity (ISS) theory is applied to deduce the velocity profile and the corresponding flow resistance law. Then the available database of measurements carried out by clear water and sediment-laden flows with sediments having a quasi-uniform sediment size and three different values of the mean particle diameter Dm (0.88 mm, 0.41 mm and 0.30 mm) are used to calibrate the parameter of the power-velocity profile). The fitting of the measured local velocity to the power distribution demonstrates that (i) for clear flow the exponent δ) can be estimated by the equation of Castaing et al. and (ii) for the sediment-laden flows δ is related to the diameter Dm. A relationship for estimating the parameter Гv obtained by the power-velocity profile) and that Гf of the flow resistance law) is theoretically deduced. The relationship between the parameter Гv, the head loss per unit length and the pipe flow Froude number is also obtained by the available sediment-laden pipe flow data. Finally, the procedure to estimate the Darcy–Weisbach friction factor is tested by the available measurements.

scholarly journals Overland Flow Resistance Law under Sparse Stem Vegetation Coverage

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1657
Author(s):  
Jingzhou Zhang ◽  
Shengtang Zhang ◽  
Si Chen ◽  
Ming Liu ◽  
Xuefeng Xu ◽  
...  
Keyword(s):  
Flow Resistance ◽  
Overland Flow ◽  
Vegetation Coverage ◽  
Dominant Factor ◽  
Roughness Coefficient ◽  
Hydraulic Parameters ◽  
Slope Condition ◽  
Manning Roughness ◽  
The Relationship ◽  
Manning Roughness Coefficient

To explore the characteristics of overland flow resistance under the condition of sparse vegetative stem coverage and improve the basic theoretical research of overland flow, the resistance characteristics of overland flow were systematically investigated under four slope gradients (S), seven flow discharges (Q), and six degrees of vegetation coverage (Cr). The results show that the Manning roughness coefficient (n) changes with the ratio of water depth to vegetation height (h/hv) while the Reynolds number (Re), Froude number (Fr), and slope (S) are closely related to vegetation coverage. Meanwhile, h/hv, Re, and Cr have strong positive correlations with n, while Fr and S have strong negative correlations with n. Through data regression analysis, a power function relationship between n and hydraulic parameters was observed and sensitivity analysis was performed. It was concluded that the relationship between n and h/hv, Re, Cr, Q, and S shows the same law; in particular, for sparse stem vegetation coverage, Cr is the dominant factor affecting overland flow resistance under zero slope condition, while Cr is no longer the first dominant factor affecting overland flow resistance under non-zero slope condition. In the relationship between n and Fr, Cr has the least effect on overland flow resistance. This indicates that when Manning roughness coefficient is correlated with different hydraulic parameters, the same vegetation coverage has different effects on overland flow resistance. Therefore, it is necessary to study overland flow resistance under the condition of sparse stalk vegetation coverage.

scholarly journals Experimental investigation of thermal-hydraulic characteristics of direct-flow honeycomb seal at the injection of cooling air.

2015 ◽  
Vol 2015 (3) ◽  
pp. 62-71
Author(s):  
Максим Шилин ◽  
Maksim Shilin ◽  
Виктор Перевезенцев ◽  
Viktor Perevezentsev ◽  
Игорь Усачев ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Resistance ◽  
Honeycomb Structure ◽  
Geometrical Parameters ◽  
Hydraulic Characteristics ◽  
Direct Flow ◽  
Honeycomb Seal ◽  
Honeycomb Seals ◽  
Cooling Air ◽  
The Relationship

Experimentally studied the influence of operational and geometrical parameters on flow resistance and heat transfer in honeycomb seals. The relationship between the nature of changes in the degree of intensification of hydraulic resistance, heat and vortex structure in the space of the cell. The effect of blowing cooling air through the surface of the honeycomb structure on the thermal hydraulic characteristics of the seal.

G206 Experimental Investigation on the Relationship between Roughness Parameter of Non-Uniform Surface Roughness and Flow Resistance

2010 ◽  
Vol 2010 (0) ◽  
pp. 551-552
Author(s):  
Ayumu MATSUMOTO ◽  
Toshihisa ITO ◽  
Masaaki MOTOZAWA ◽  
Hideki KAWASHIMA ◽  
Hirotomo ANDO ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Experimental Investigation ◽  
Flow Resistance ◽  
Roughness Parameter ◽  
The Relationship

Land application of farm dairy effluent to a mole and pipe drained soil: implications for nutrient enrichment of winter-spring drainage

Soil Research ◽  
2008 ◽  
Vol 46 (1) ◽  
pp. 45 ◽  
Author(s):  
D. J. Houlbrooke ◽  
D. J. Horne ◽  
M. J. Hedley ◽  
V. O. Snow ◽  
J. A. Hanly
Keyword(s):  
Nutrient Enrichment ◽  
Dairy Farm ◽  
Irrigation Scheduling ◽  
Land Application ◽  
Aquatic Weed ◽  
Dairy Effluent ◽  
Weed Growth ◽  
Treated Effluent ◽  
Quality Of Water ◽  
Farm Dairy Effluent

Spray irrigation of farm dairy effluent (FDE) to artificially drained land in accordance with deferred irrigation criteria causes minimal direct drainage of partially treated FDE at the time of irrigation. The influence of deferred irrigation of FDE on the subsequent nutrient enrichment of winter–spring drainage from mole and pipe systems is unknown. Research was conducted in the Manawatu region, New Zealand, to investigate the influence of deferred irrigation of FDE on the quality of water in artificial drainage. The experimental site was established on a Pallic soil (Tokomaru silt loam) at the No. 4 dairy farm at Massey University, Palmerston North. There were 6 plots (each 40 m by 40 m), each with an isolated mole and pipe drainage network. Four of the plots received fertiliser according to the farm’s fertiliser program (non-effluent plots), while the other 2 plots received applications of FDE according to the deferred irrigation scheduling criteria (effluent plots). All of the plots were subject to the farm’s standard grazing management.The average concentrations of N and P in the 2003 winter drainage (average 236 mm) from both the non-effluent and FDE irrigated plots were well above the threshold concentrations that stimulate aquatic weed growth in fresh water bodies. Annual nutrient losses of 31.4 kg N ha/year and 0.65 kg P ha/year in drainage were recorded for non-effluent plots. Deferred irrigation of FDE in the summer period did not increase the loss of N in winter–spring drainage (N loss from effluent plots was 31.1 kg N ha/year) but did cause a significant increase (P < 0.001) in total P in drainage (an additional 1.03 kg P/ha, c. 160% of losses from non-effluent plots, a loss of 3.3% of applied P). Furthermore, an irrigation of FDE to near-saturated soil in mid September resulted in the direct drainage of partially treated effluent, and hence, N and P concentrations in drainage were 6–10-fold greater than those that would normally be expected from drainage events induced by winter–spring rainfall. This illustrates the importance of scheduling FDE irrigation in accordance with deferred irrigation principles.

scholarly journals Vermicomposting of aquatic weeds: A quick review

2017 ◽  
Vol 4 (3) ◽  
pp. 133-136 ◽  
Author(s):  
Ishtiyaq Ahmed Najar
Keyword(s):  
Large Scale ◽  
Anthropogenic Activities ◽  
Effective Control ◽  
Growth Media ◽  
Aquatic Weed ◽  
Aquatic Weeds ◽  
Earthworm Species ◽  
Weed Growth ◽  
Wide Range ◽  
Rich Material

Aquatic plants play an important role in ecosystem functioning and services but they can also be deleterious if present in excess. The different anthropogenic activities result in accumulation of nutrients in aquatic ecosystems leads to eutrophication with massive weed growth and associated diverse adverse effects. Effective control/management of weeds in different aquatic systems is not only difficult but of short duration. The commonly used methods to manage/control the aquatic weeds are biological, chemical and mechanical, in addition to habitat manipulation. However, these methods can be highly disruptive causing adverse environmental effects and are relatively inefficient. On the other hand different species of earthworms can feed on wide range of weeds and convert them into stable product called vermicompost, rich in plant nutrients. Among different aquatic weeds the most extensively vermicomposted weed is water hyacinth (Eichhornia crassipes (Mart.) Solms), using different earthworm species. Among different earthworm species used for vermicomposting of aquatic weeds, Eisenia fetida (Savigny) is the most commonly used species. Vermicomposting is an efficient ecobiotechnological process that converts the aquatic weeds into nutrient rich material that can acts as suitable plant growth media for sustainable agroecosystems. Further large scale utilization of aquatic weed based vermicompost in horticulture can solve their management and disposal issues along with restoration of organic matter and nutrient depletion at low input basis.

scholarly journals Effects of Biochar Addition on Rill Flow Resistance

Water ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3036
Author(s):  
Alessio Nicosia ◽  
Vincenzo Pampalone ◽  
Vito Ferro
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Flow Resistance ◽  
Accurate Estimate ◽  
Power Equation ◽  
Flow Turbulence ◽  
Bed Slope ◽  
The Relationship ◽  
Resistance Equation ◽  
Rill Flow

The development of rills on a hillslope whose soil is amended by biochar remains a topic to be developed. A theoretical rill flow resistance equation, obtained by the integration of a power velocity distribution, was assessed using available measurements at plot scale with a biochar added soil. The biochar was incorporated and mixed with the arable soil using a biochar content BC of 6 and 12 kg m−2. The developed analysis demonstrated that an accurate estimate of the velocity profile parameter Гv can be obtained by the proposed power equation using an exponent e of the Reynolds number which decreases for increasing BC values. This result pointed out that the increase of biochar content dumps flow turbulence. The agreement between the measured friction factor values and those calculated by the proposed flow resistance equation, with Гv values estimated by the power equation calibrated on the available measurements, is characterized by errors which are always less than or equal to ±10% and less than or equal to ±3% for 75.0% of cases. In conclusion, the available measurements and the developed analysis allowed for (i) the calibration of the relationship between Гv, the bed slope, the flow Froude number, and the Reynolds number, (ii) the assessment of the influence of biochar content on flow resistance and, (iii) stating that the theoretical flow resistance equation gives an accurate estimate of the Darcy–Weisbach friction factor for rill flows on biochar added soils.

Environmental considerations in the development of diquat and paraquat as aquatic herbicides

1972 ◽  
Vol 7 (2) ◽  
pp. 51-54 ◽  
Author(s):  
A Calderbank
Keyword(s):  
Fresh Water ◽  
Natural Waters ◽  
Environmental Hazards ◽  
Aquatic Weed ◽  
Recreational Value ◽  
Weed Growth ◽  
Pumping Stations ◽  
Irrigation Channels ◽  
Aquatic Herbicides ◽  
Environmental Considerations

As the world's requirement for fresh water expands, so does the problem of increased aquatic weed growth due to enrichment of natural waters. Weeds impair the recreational value of lakes and streams; they also hinder navigation, block irrigation channels and cause problems in pumping stations and hydroelectric turbines; but herbicides for their control must be safe and not introduce environmental hazards. Diquat and paraquat have many advantages for this purpose.

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