scholarly journals RIVERBED EVOLUTION OF YANGTZE ESTUARY AND ITS RESPONSE TO THE HYDRODYNAMIC CHANGES AT UPSTREAM

2012 ◽  
Vol 1 (33) ◽  
pp. 92
Author(s):  
Yongping Chen ◽  
Ninglin Jiang ◽  
Changkuan Zhang
Keyword(s):  
Cross Sections ◽  
Water Depth ◽  
River Discharge ◽  
Numerical Experiments ◽  
Yangtze Estuary ◽  
Main Channel ◽  
Depth Profiles ◽  
Discharge Ratio ◽  
Upper Boundary

The riverbed evolution of upper part of Yangtze estuary, Chengtong reach, is analyzed by comparison of 6 sets of bathymetry data during 1977~2011. The significant changes of water depth profiles along 6 representative cross-sections indicate the reach is still in the process of development. In order to get a better understanding of the effect of river discharge at upstream on the riverbed evolution of Chengtong reach, a series of numerical experiments are implemented by specifying different river discharge conditions at the upper boundary. The corresponding discharge ratio at main sub-reaches is compared to reveal the response of the riverbed evolution to the hydrodynamic changes at upstream. The results show that with the increase of river discharge, the discharge ratio in the main channels of Fujiangsha sub-reach and Rugaosha sub-reach increases, but it changes to decrease when the upstream river discharge becomes very large; however, the discharge ratio in the main channel of Tongzhousha sub-reach always decreases with the increase of river discharge at upstream.

scholarly journals An experimental study of branching flow in open channels

2019 ◽  
Vol 19 (2) ◽  
pp. 93-101
Author(s):  
Tarek Sayed
Keyword(s):  
Water Resources ◽  
Channel Flow ◽  
Water Depth ◽  
Discharge Rate ◽  
Laboratory Data ◽  
Main Channel ◽  
Network Systems ◽  
Widespread Application ◽  
Discharge Ratio ◽  
Branching Angle

Abstract Branching channel flow describes any side water withdrawals from rivers or main channels. Branching channels have widespread application in many practical projects, such as irrigation and drainage network systems, water and waste-water treatment plants, and many water resources projects. Therefore, in this research, a comprehensive analysis of laboratory data has been carried out to discover the best angle of branching. The study also aims to introduce simple, practical equations to help engineers of water resources to fix the percentage of discharge diverted to the branch channel. The study was carried out in the Irrigation and hydraulics laboratory of the civil department, Faculty of Engineering, Assiut University. The laboratory channel consisted of two parts, the main channel, and a branch channel. The main channel was 8.0 m in length, 20 cm wide, and 20 cm in depth. The division corner to the branch channel was sharp edged and located 5.0 m downstream of the main channel inlet. The branch channel was 3.0 m long, 20 cm in depth and its width was changed three times (10, 15, and 20 cm) respectively. A total of 84 runs were carried out. Investigations of the flow into the branching channel show that the branching discharge depends on many interlinked parameters. It increases with a decrease of the main channel flow velocity and the Froude number upstream of the branch channel junction. It also increases with an increase in the Yb / Yu ratio. In subcritical flow, water depth in the branch channel is always lower than the main channel water depth. The flow diversion to the branch channel leads to a decrease in water depth downstream of the main channel. In addition, the study showed that the highest discharge rate was obtained when the angle of branching was equal to 45° and then an angle of 60o. While the lowest discharge rate was obtained at an angle of 90°. Furthermore, at Br = 1.0, using a branching angle equal to 45° the discharge ratio (Qr) increases from about 4.42 to 19.01%, more than that obtained with using the branching angle equal 90°, while the discharge ratio (Qr) increases from about 0.52 to 49.18% and 1.51 to 24.79%, at Br = 0.75, and Br = 0.5 respectively.

Monitoring and Assessment of Water Quality in Fuchunjiang and Hangzhou Reaches of Qiantangjiang Estuarine Zone

2013 ◽  
Vol 316-317 ◽  
pp. 711-714
Author(s):  
Zhi Yong Dong ◽  
Yong Gu ◽  
Shuo Shuo Wang ◽  
Ying Biao Shi ◽  
Ruo Hua Li ◽  
...  
Keyword(s):  
Water Quality ◽  
Cross Section ◽  
Cross Sections ◽  
Ph Value ◽  
Flood Plain ◽  
Quality Parameters ◽  
Main Channel ◽  
Water Quality Parameters ◽  
Vertical Line ◽  
Estuarine Zone

This paper presents monitoring investigation of water quality parameters in Fuchunjiang and Hangzhou reaches of Qiantang estuarine zone by YSI 6600 V2-4-M multi-parameter water quality sonde. The 7 monitoring cross-sections were streamwise placed, and the 2 vertical lines respectively located in flood plain and main channel at each cross-section. Surface, intermediate and bed layers were chosen at each vertical line in main channel, and surface and bed layers at each vertical line in flood plain. At each vertical line, the main water quality parameters such as dissolved oxygen, salinity, turbidity, pH value, electrical conductivity and oxidation reduction potential were monitored, variation of these parameters along longitudinal and vertical directions analyzed, and water quality conditions at each monitoring cross-section assessed.

scholarly journals Physical modelling of energy losses at surcharged three-way junction manholes in drainage system

2021 ◽  
Author(s):  
Q. Li ◽  
J. Xia ◽  
M. Zhou ◽  
S. Deng ◽  
H. Zhang ◽  
...  
Keyword(s):  
Energy Loss ◽  
Flow Structure ◽  
Water Depth ◽  
Drainage System ◽  
Physical Modelling ◽  
Head Loss ◽  
Geometrical Parameters ◽  
Flow Discharge ◽  
Discharge Ratio ◽  
Loss Coefficients

Abstract Motivated by the observation that vortex flow structure was evident in the energy loss at the surcharged junction manhole due to changes of hydraulic and geometrical parameters, a physical model was used to calculate energy loss coefficients and investigate the relationship between flow structure and energy loss at the surcharged three-way junction manhole. The effects of the flow discharge ratio, the connected angle between two inflow pipes, the manhole geometry, and the downstream water depth on the energy loss were analyzed based on the quantified energy loss coefficients and the identified flow structure. Moreover, two empirical formulae for head loss coefficients were validated by the experimental data. Results indicate that the effect of flow discharge ratio and connected angle are significant, while the effect of downstream water depth is not obvious. With the increase of the lateral inflow discharge, the flow velocity distribution and vortex structure are both enhanced. It is also found that a circular manhole can reduce local energy loss when compared to a square manhole. In addition, the tested empirical formulae can reproduce the trend of total head loss coefficient.

scholarly journals Theoretical Gravity Anomalies of Glaciers Having Parabolic Cross-Sections

1964 ◽  
Vol 5 (38) ◽  
pp. 255-257 ◽  
Author(s):  
Charles E. Corbató
Keyword(s):  
Cross Sections ◽  
Lower Boundary ◽  
Gravity Anomalies ◽  
Vertical Axis ◽  
Two Dimensional ◽  
Axis Of Symmetry ◽  
Upper Boundary

AbstractEquations and a graph are presented for calculating gravity anomalies on a two-dimensional glacier model having a horizontal upper boundary and a lower boundary which is a parabola with a vertical axis of symmetry.

Sediments of the Tay Estuary. II. Formation of Ephemeral Zones of High Suspended Sediment Concentrations.

1975 ◽  
Vol 75 (1-2) ◽  
pp. 65-89 ◽  
Author(s):  
A. T. Buller
Keyword(s):  
Suspended Sediment ◽  
River Discharge ◽  
High Tide ◽  
High Water ◽  
Main Channel ◽  
Tidal State ◽  
Suspended Sediment Concentrations ◽  
High Concentrations ◽  
Calm Weather ◽  
Dry Out

SynopsisDuring periods of sustained moderate river discharge and quiescent marine conditions little external suspended sediment enters the estuarine circulation of the Tay. That material which is in suspension is largely derived from the estuary margins where tidal currents superimposed by wind-induced waves are competent to resuspend fine material from the surface of the ‘mud’ flats and erode bedded silts from the incised banks of minor channels and runnels draining them. The quantities of this sediment entering the system are largely determined by tidal state and amplitude, as well as wind velocity.On spring tides the flats are entirely covered at high water, and dry out completely at low water. The volume of water and its areal coverage at high tide ensures that, during the ebb, water charged with high concentrations of suspended sediment is directed from the fiats into the surface and middepth waters of the main channel. This process acting along the 20 km length of the channel flanking the ‘mud’ flats, combined with the low tide ‘ponding effect’ caused by the tide flooding from the sea while the upper estuarine water is still ebbing, results in the cumulative formation of a zone of high suspended sediment concentrations (turbidity maximum). As the flood tide becomes fully established the zone is diluted and dispersed. During neap tides the same processes operate, but because a smaller area of the flats is covered at high water and uncovered at low water, and because neap tidal current speeds are lower than those for spring tides, two proportionally weaker zones are recognised.Following periods of sustained moderate river discharge, quiet sea conditions and calm weather, suspended sediment concentrations in the Tay are negligible irrespective of tidal state or amplitude.

scholarly journals Reliability and Comparison of Some GEANT4-DNA Processes and Models for Proton Transportation: An Ultra-Thin Layer Study

2021 ◽  
Author(s):  
Gabriela Hoff ◽  
Raquel S. Thomaz ◽  
Leandro I. Gutierres ◽  
Sven Muller ◽  
Viviana Fanti ◽  
...  
Keyword(s):  
Cross Sections ◽  
Radiation Transport ◽  
Thin Layers ◽  
Depth Profiles ◽  
Chemical Damage ◽  
Diffusion Parameters ◽  
Experiment Versus ◽  
Deposited Energy ◽  
Simulation Results ◽  
Dynamic Diffusion

This chapter presents a specific reliability study of some GEANT4-DNA (version 10.02.p01) processes and models for proton transportation considering ultra-thin layers (UTL). The Monte Carlo radiation transport validation is fundamental to guarantee the simulation results accuracy. However, sometimes this is impossible due to the lack of experimental data and, it is then that the reliability evaluation takes an important role. Geant4-DNA runs in an energy range that makes impossible, nowadays, to perform a proper microscopic validation (cross-sections and dynamic diffusion parameters) and allows very limited macroscopic reliability. The chemical damage cross-sections reliability (experiment versus simulation) is a way to verify the consistency of the simulation results which is presented for 2 MeV incident protons beam on PMMA and PVC UTL. A comparison among different Geant4-DNA physics lists for incident protons beams from 2 to 20 MeV, interacting with homogeneous water UTL (2 to 200 nm) was performed. This comparison was evaluated for standard and five other optional physics lists considering radial and depth profiles of deposited energy as well as number of interactions and stopping power of the incident particle.

scholarly journals Stratification effects on shoaling Internal Solitary Waves

2021 ◽  
Author(s):  
Sam Hartharn-Evans ◽  
Magda Carr ◽  
Marek Stastna ◽  
Peter Davies
Keyword(s):  
Density Gradient ◽  
Solitary Waves ◽  
Numerical Experiments ◽  
Lower Layer ◽  
Internal Solitary Waves ◽  
Topographic Slope ◽  
Numerical Studies ◽  
The World ◽  
Upper Boundary ◽  
Mixing And Transport

<p>Shoaling is a key mechanism by which Internal Solitary Waves (ISWs) dissipate energy, induce mixing, and transport sediment. Past studies of shoaling ISWs in a three-layer stratification (with homogeneous upper and lower layers separated by a thin pycnocline layer) have identified a classification system where waves over the shallowest slopes undergo fission, whilst over steeper slopes, the breaking type changes from surging, through collapsing to plunging as a function of increasing internal Irribaren number (Ir) defined with the topographic slope, s, and the incident wave’s amplitude and wavelength, A<sub>w</sub> and L<sub>w </sub>respectively, as <img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.9fb46536f70067154311161/sdaolpUECMynit/12UGE&app=m&a=0&c=d84eaf790c6586a46ed8fca09040fcd7&ct=x&pn=gnp.elif&d=1" alt="" width="117" height="24">. Here, a combined numerical and laboratory study extends this prior work into new stratifications, representing the diversity of ocean structures across the world. Numerical results were able to successfully reproduce past studies in the three-layer stratification, and those in the two-layer stratification in the laboratory. Where a linear stratified layer overlays a homogeneous lower layer (two-layer stratification), it is found that plunging dynamics are inhibited by the density gradient throughout the upper layer, instead forming collapsing-type breakers. In numerical experiments, where the density gradient is continuous throughout the full water column (linear stratification), not only are the plunging dynamics inhibited, but the density gradient at the bottom boundary also prevents the formation of collapsing dynamics, instead all waves in this stratification either fission, or form surging breakers. Where the wave steepness is particularly high in the linear stratification, the upslope bolus formed by surging was unstable, and Kelvin-Helmholtz instabilities were observed on the upper boundary of the bolus, dynamics not previously observed in the literature. These results indicate the importance of using representative stratifications in laboratory and numerical studies of ISW behaviours.</p>

scholarly journals JUMLAH TRAKEA PADA DAUN LUDWIGIA ADSCENDENS (L.) HARA DALAM KONDISI TERGENANG : SEBUAH GEJALA PLASTISITAS ANATOMI ##plugins.themes.bootstrap3.article.sidebar##

1999 ◽  
Vol 4 (2) ◽  
pp. 111
Author(s):  
Joko Budiono
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Water Depth ◽  
Vascular Bundle ◽  
Water Surface ◽  
Anatomical Structure ◽  
Leaf Primordium ◽  
Aquatic Weed ◽  
Paraffin Method ◽  
Ludwigia Adscendens

This study was conducted to reveal the influence of waterlogging on the number of tracheas in each vascular bundle of Ludwigia adscendens (L.) Hara leaf. This plant is well known as aquatic weed which can grow floating on water surface. The leaf primordium extend across the water from 10-15 cm below water surface. The plant was grown in aquarium at 0, 10 and 15 cm water depth. The observed leaves were first, third and fifth the base. Anatomical structure were analyzed using serial cross sections of he leaf the cross section were made by paraffin method. The data were analyzed using ANOVA and DMRT method. The result showed that significance difference on the number of tracheas in each vascular bundle were found among leaves of different depth.

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