scholarly journals Effects of vegetation lodging on overland runoff flow regime and resistance

2020 ◽  
Vol 20 (4) ◽  
pp. 1463-1473
Author(s):  
Jingzhou Zhang ◽  
Shengtang Zhang ◽  
Guibao Li ◽  
Ming Liu ◽  
Si Chen
Keyword(s):  
Flow Regime ◽  
Water Depth ◽  
Overland Flow ◽  
Resistance Coefficient ◽  
Soil Consolidation ◽  
Slope Engineering ◽  
Overland Runoff ◽  
Flow Propagation ◽  
Water Depths ◽  
Fluid Characteristics

Abstract Vegetation is a vital part of the natural environment. Variations in vegetation morphology produce changes in the mechanical and fluid characteristics of overland flow. Determining the effects of vegetation lodging on the overland runoff flow regime and resistance is a prerequisite for accurately simulating overland runoff and convergence, revealing the mechanism of overland flow propagation, and the design and management of vegetation protection, soil consolidation, and ecological slope engineering. To systematically study the effects of vegetation lodging on overland runoff, four planting vegetation lodging angles (α) and 10 test water depths were used to simulate experimental research with a 1.0% slope ratio. Experimental results show that the depth and state of vegetation inundation and the degree of lodging significantly influence the flow regime and resistance. Under the same water depth, higher values of α are associated with higher values of the flow velocity, Reynolds number, Froude number, and Darcy–Weisbach resistance coefficient (f), and lower values of the drag coefficient (CD). The overall result is enhanced turbulence in the flow field and weaker flow resistance. Numerical statistics and difference analysis indicate that, when the vegetation is non-submerged, a 10° increase in α produces a 9.30% decrease in f. In the submerged state, a 10° increase in α causes a 26.70% decrease in f. CD is greatly affected by the boundary water depth. Below some critical water depths, an increase of 10° in α reduces CD by 8.48%. Above the critical depth, a 10° increase in α decreases CD by 41.10%.

scholarly journals Microplastic contamination of the drilling bivalve Hiatella arctica in Arctic rhodolith beds

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sebastian Teichert ◽  
Martin G. J. Löder ◽  
Ines Pyko ◽  
Marlene Mordek ◽  
Christian Schulbert ◽  
...  
Keyword(s):  
Polyethylene Terephthalate ◽  
Water Depth ◽  
The Arctic ◽  
Polymer Composition ◽  
Bivalve Species ◽  
Filter Feeder ◽  
Hiatella Arctica ◽  
Long Term Consequences ◽  
Water Depths

AbstractThere is an increasing number of studies reporting microplastic (MP) contamination in the Arctic environment. We analysed MP abundance in samples from a marine Arctic ecosystem that has not been investigated in this context and that features a high biodiversity: hollow rhodoliths gouged by the bivalve Hiatella arctica. This bivalve is a filter feeder that potentially accumulates MPs and may therefore reflect MP contamination of the rhodolith ecosystem at northern Svalbard. Our analyses revealed that 100% of the examined specimens were contaminated with MP, ranging between one and 184 MP particles per bivalve in samples from two water depths. Polymer composition and abundance differed strongly between both water depths: samples from 40 m water depth showed a generally higher concentration of MPs and were clearly dominated by polystyrene, samples from 27 m water depth were more balanced in composition, mainly consisting of polyethylene, polyethylene terephthalate, and polypropylene. Long-term consequences of MP contamination in the investigated bivalve species and for the rhodolith bed ecosystem are yet unclear. However, the uptake of MPs may potentially impact H. arctica and consequently its functioning as ecosystem engineers in Arctic rhodolith beds.

scholarly journals Production and water yield of cauliflower under irrigation depths and nitrogen doses

2019 ◽  
Vol 23 (8) ◽  
pp. 561-565
Author(s):  
Reginaldo M. de Oliveira ◽  
Rubens A. de Oliveira ◽  
Sanzio M. Vidigal ◽  
Ednaldo M. de Oliveira ◽  
Lorença B. Guimarães ◽  
...  
Keyword(s):  
Water Depth ◽  
Irrigation Water ◽  
Water Yield ◽  
Crop Evapotranspiration ◽  
Fresh Weight ◽  
Randomized Design ◽  
Mean Diameter ◽  
Irrigation Depth ◽  
Completely Randomized Design ◽  
Water Depths

ABSTRACT Cauliflower is a brassica produced and consumed in Brazil, whose cultivation depends on the adequate supply of water and nutrients. The objective of this study was to evaluate the effect of irrigation depths and nitrogen doses on the production components and water yield of cauliflower hybrid Barcelona CMS. The treatments consisted of five irrigation water depths (0, 75, 100, 125 and 150% of the crop evapotranspiration) combined with five nitrogen doses (0, 75, 150, 300 and 450 kg ha-1). The experiment was conducted in a completely randomized design with a split-plot arrangement. The effects of these factors were evaluated using the response surface methodology. The water yield of the crop decreases with increasing irrigation water depth; therefore, the yield is higher when water replenishment is lower than the recommended. The highest estimated total inflorescence yield is 24,547.80 kg ha-1, with a inflorescence mean diameter of 19.60 cm, a inflorescence mean height of 12.25 cm, and an inflorescence fresh weight of 858.90 g plant-1, obtained with an irrigation water depth equivalent to 132.09% of the crop evapotranspiration (ETc) and a nitrogen dose of 450 kg ha-1. The highest inflorescence diameter and height are obtained with an irrigation depth equivalent to 128.70 and 108.20% of ETc, respectively, and a nitrogen dose of 450 kg ha-1. Therefore, the best productivity response of the Barcelona CMS cauliflower hybrid can be obtained using an irrigation depth greater than the crop evapotranspiration, regardless of the nitrogen doses.

Mechanical Qualification of Dynamic Deep Water Power Cable

2011 ◽  
Author(s):  
Roger Slora ◽  
Stian Karlsen ◽  
Per Arne Osborg
Keyword(s):  
Water Depth ◽  
Deep Water ◽  
Failure Modes ◽  
Electrical Power ◽  
Oil And Gas Industry ◽  
Electrical Heating ◽  
Power Cable ◽  
Water Power ◽  
System Integrity ◽  
Water Depths

There is an increasing demand for subsea electrical power transmission in the oil- and gas industry. Electrical power is mainly required for subsea pumps, compressors and for direct electrical heating of pipelines. The majority of subsea processing equipment is installed at water depths less than 1000 meters. However, projects located offshore Africa, Brazil and in the Gulf of Mexico are reported to be in water depths down to 3000 meters. Hence, Nexans initiated a development programme to qualify a dynamic deep water power cable. The qualification programme was based on DNV-RP-A203. An overall project plan, consisting of feasibility study, concept selection and pre-engineering was outlined as defined in DNV-OSS-401. An armoured three-phase power cable concept assumed suspended from a semi-submersible vessel at 3000 m water depth was selected as qualification basis. As proven cable technology was selected, the overall qualification scope is classified as class 2 according to DNV-RP-A203. Presumed high conductor stress at 3000 m water depth made basis for the identified failure modes. An optimised prototype cable, with the aim of reducing the failure mode risks, was designed based on extensive testing and analyses of various test cables. Analyses confirmed that the prototype cable will withstand the extreme loads and fatigue damage during a service life of 30 years with good margins. The system integrity, consisting of prototype cable and end terminations, was verified by means of tension tests. The electrical integrity was intact after tensioning to 2040 kN, which corresponds to 13 000 m static water depth. A full scale flex test of the prototype cable verified the extreme and fatigue analyses. Hence, the prototype cable is qualified for 3000 m water depth.

An Experimental Study of Shallow Water Wave Statistics on Mild Bed Slopes

2011 ◽  
Author(s):  
Vasiliki Katsardi ◽  
Chris Swan
Keyword(s):  
Water Depth ◽  
Measured Data ◽  
Intermediate Water ◽  
Statistical Distributions ◽  
Spectral Bandwidth ◽  
Peak Period ◽  
Wave Statistics ◽  
Wave Heights ◽  
Bed Slope ◽  
Water Depths

This paper describes a new series of laboratory observations, undertaken in a purpose built wave flume, in which a number of scaled simulations of realistic ocean spectra were allowed to evolve over a range of mild bed slopes. The purpose of the study was to examine the distribution of wave heights and its dependence on the local water depth, d, the local bed slope, m, and the nature of the input spectrum; the latter considering variations in the spectral peak period, Tp, the spectral bandwidth and the wave steepness. The results of the study show that for mild bed slopes the statistical distributions of wave heights are effectively independent of both the bed slope and the spectral bandwidth. However, the peak period plays a very significant role in the sense that it alters the effective water depth. Following detailed comparisons with the measured data, the statistical distributions for wave heights in relatively deep water are found to be in reasonable agreement with the Forristall [1] and Glukhovskii [2] distributions. For intermediate water depths, the Battjes & Groenendijk [3] distribution works very well. However, for the shallowest water depths none of the existing distributions provides good agreement with the measured data; all leading to an over-estimate of the largest wave heights.

scholarly journals Productive characteristics of banana genotypes submitted to different irrigation water depths under Cerrado conditions

2017 ◽  
Vol 38 (4Supl1) ◽  
pp. 2351
Author(s):  
Luciana Borges e Silva ◽  
Jorge Luís do Nascimento ◽  
Ronaldo Veloso Naves ◽  
Juracy Rocha Braga Filho ◽  
Wilian Henrique Diniz Buso ◽  
...  
Keyword(s):  
Water Depth ◽  
Irrigation Water ◽  
Potential Evapotranspiration ◽  
Block Design ◽  
Irrigation Management ◽  
Fruit Production ◽  
Production Cycle ◽  
Fruit Length ◽  
Water Depths ◽  
Fruit Diameter

Irrigation management associated with other banana agricultural practices can provide an increased productivity and improved fruit quality. This study assessed the productive characteristics of banana genotypes under different irrigation water depths. The experiment was conducted at the experimental area of the School of Agronomy (EA/UFG) in Goiânia, GO, Brazil. The experimental design was a split-plot randomized block design, in which four irrigation water depths (30, 65, 100, and 135% of crop potential evapotranspiration, ETpc) composed the plots and three genotypes (‘FHIA 18’, ‘Grande-Naine’, and ‘Prata’) the subplots, with a spacing of 2.5 × 1.6 m. During the experimental period (first production cycle), the total precipitation was 1719.20 mm. Characterization of genotype development and yield was performed with the following assessments: bunch mass (kg), number of hands, stalk mass (kg), fruit diameter of the second hand (mm), fruit length of the second hand (cm), mass of the second hand (kg), number of fruits of the second hand, total number of fruits, and number of damaged fruits. The cultivar ‘FHIA 18’, differently from the others, showed a significant response to irrigation water depths on productivity. In the genotypes ‘Grande-Naine’ and ‘Prata’, an influence of irrigation was observed only on external and visual characteristics of fruit (diameter, length, and number of damaged fruits). In the genotype ‘Prata’, the irrigation water depth of 965 mm allowed fruit production with a larger diameter. Fruit length in the genotype ‘Prata’ increased linearly as water depth increased. The use of irrigation promoted a reduction in the number of damaged fruits in the genotypes ‘FHIA 18’ and ‘Grande-Naine’.

scholarly journals Detonation and Transition to Detonation in Partially Water-Filled Pipes

2012 ◽  
Author(s):  
Neal P. Bitter ◽  
Joseph E. Shepherd
Keyword(s):  
Water Depth ◽  
Water Pressure ◽  
Detonation Pressure ◽  
Shock Train ◽  
Hoop Strain ◽  
Pressure Transducers ◽  
Horizontal Pipes ◽  
Gas Layer ◽  
Transition To Detonation ◽  
Water Depths

Detonations and deflagration-to-detonation transition (DDT) are experimentally studied in horizontal pipes which are partially filled with water. The gas layer above the water is stoichiometric hydrogen-oxygen at 1 bar. For detonation cases, ignition and transition occur outside of the water-filled section. For DDT cases, ignition and transition occur over the surface of the water. Pressure and hoop strain are measured incrementally along the pipe, with pressure transducers located both above and below the water. The detonation wave produces an oblique shock train in the water, and the curvature of the pipe is seen to focus the shocks at the bottom, resulting in peak pressures that are 4–6 times higher than the peak detonation pressure. Such pressure amplification is observed for water depths of 0.25, 0.5, 0.75, 0.87, and 0.92 pipe diameters. For a water depth of 0.5 diameters, pressure is also recorded at several circumferential locations in order to measure the shock focusing phenomenon. Peak hoop strains are found to decrease with increasing water depth, and transition to detonation is seen to occur for water depths as high as 0.92 pipe diameters.

scholarly journals Laboratory investigation of crest height statistics in intermediate water depths

2019 ◽  
Vol 475 (2229) ◽  
pp. 20190183 ◽  
Author(s):  
I. Karmpadakis ◽  
C. Swan ◽  
M. Christou
Keyword(s):  
Water Depth ◽  
Wave Breaking ◽  
Field Data ◽  
Full Range ◽  
Second Order ◽  
Intermediate Water ◽  
Sea State ◽  
Nonlinear Amplification ◽  
Effective Water ◽  
Water Depths

This paper concerns the statistical distribution of the crest heights associated with surface waves in intermediate water depths. The results of a new laboratory study are presented in which data generated in different experimental facilities are used to establish departures from commonly applied statistical distributions. Specifically, the effects of varying sea-state steepness, effective water depth and directional spread are investigated. Following an extensive validation of the experimental data, including direct comparisons to available field data, it is shown that the nonlinear amplification of crest heights above second-order theory observed in steep deep water sea states is equally appropriate to intermediate water depths. These nonlinear amplifications increase with the sea-state steepness and reduce with the directional spread. While the latter effect is undoubtedly important, the present data confirm that significant amplifications above second order (5–10%) are observed for realistic directional spreads. This is consistent with available field data. With further increases in the sea-state steepness, the dissipative effects of wave breaking act to reduce these nonlinear amplifications. While the competing mechanisms of nonlinear amplification and wave breaking are relevant to a full range of water depths, the relative importance of wave breaking increases as the effective water depth reduces.

scholarly journals Agronomic features of elephant grass (Pennisetum purpureum Schum) cv. Roxo under irrigation

2018 ◽  
Vol 39 (1) ◽  
pp. 275
Author(s):  
Ana Paula da Silva Carvalho ◽  
Roney Mendes de Arruda ◽  
Joadil Gonçalves de Abreu ◽  
Alexandre Lima de Souza ◽  
Rosane Cláudia Rodrigues ◽  
...  
Keyword(s):  
Plant Height ◽  
Water Depth ◽  
Dry Matter ◽  
Block Design ◽  
Pennisetum Purpureum ◽  
Dry Matter Production ◽  
Elephant Grass ◽  
Matter Production ◽  
Pennisetum Purpureum Schum ◽  
Water Depths

This study aimed to evaluate how different irrigation water depths influence the agronomical features of elephant grass (Pennisetum purpureum Schum) cv. Roxo. Grass was cultivated in a pasture belonging to the Bovine Sector of the National Agrotechnical School of Caceres – MT. The experiment was a block design with five treatments and four repetitions. Treatments consisted of five water depths: 0 = 0% of available water (AW), 1 = 21% of AW, 2 = 34% of AW, 3 = 74% of AW, and 5 = 100% of AW. Evaluated features were production (dry matter ha-1), plant height, leaf/steam ratio, and stem diameter. Dry matter production of cuts from May and July increased linearly with increasing water depth (P < 0.05). Plant height increased linearly as water depth increased in the cuts of May and September, while the height of July cuts was 71.76 cm under an irrigation depth of 390.77 mm. In May, July, and September cuts, leaf percentage decreased linearly as water depth increased (P < 0.05). An increase of 1 mm in water depth reduced leaf percentage by 0.0936% (May), 0.0295% (July), and 0.0122% (September). Our results indicate that to improve dry matter production, May, July, and September cuts should be irrigated with water depths of 56.03 mm, 601.78 mm, and 577.65 mm, respectively.

Water depths at the upper boundary for overland flow on small gradients

1995 ◽  
Vol 171 (1-2) ◽  
pp. 93-102 ◽  
Author(s):  
W.H. van der Molen ◽  
P.J.J.F. Torfs ◽  
J.L.M.P. de Lima
Keyword(s):  
Overland Flow ◽  
Water Depths ◽  
Upper Boundary

scholarly journals Effects of mycorrhizal inoculant, N:P supply ratio, and water depth on the growth and biomass allocation of three wetland plant species

2005 ◽  
Vol 83 (9) ◽  
pp. 1117-1125 ◽  
Author(s):  
Lauchlan H. Fraser ◽  
Larry M. Feinstein
Keyword(s):  
Biomass Allocation ◽  
Water Depth ◽  
Soil Surface ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Nutrient Supply ◽  
Wetland Plant ◽  
Below Ground ◽  
Root:Shoot Ratios ◽  
Water Depths

In the greenhouse, we investigated the growth and biomass allocation of three juvenile wetland species ( Carex tribuloides Wahl., Phalaris arundinacea L., and Rumex orbiculatus Gray) under three different water depths (–4, 0, and +2 cm relative to the soil surface), three N:P supply ratios (1:30, 1:1, 30:1), and two mycorrhizal inoculant treatments (arbuscular mycorrhizal (AM) fungi present, absent). After 6 weeks, the plants were harvested, separated to above- and below-ground parts, oven-dried, and weighed. The mycorrhizal inoculant significantly increased plant growth and reduced root:shoot ratios. At an N:P supply ratio of 30:1, plants with AM fungi had significantly greater biomass than those plants without AM fungi. However, at 1:1 N:P supply ratio, plants without AM fungi had greater biomass. Plants without AM fungi had higher root:shoot ratios at 0 and –4 cm water depth than plants with AM fungi. In general, C. tribuloides had the lowest growth, and unlike P. arundinacea and R. orbiculatus, was not affected by the water depth treatment. Growth of the wetland plants was limited more by nitrogen than by phosphorus. Our results suggest that at high N:P nutrient supply ratios and non-flooded conditions the growth of wetland seedlings can benefit by being inoculated with AM fungi.

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