scholarly journals Siltation characteristics of the tail reach of Ganjiang River under the regulation of estuary gates

2020 ◽  
Vol 20 (8) ◽  
pp. 3707-3714
Author(s):  
Zhi-chao Wang ◽  
Xin-fa Xu ◽  
Zhi-wen Huang ◽  
Nian-hua Wu ◽  
Su-fen Zhou
Keyword(s):  
Sediment Transport ◽  
Water Level ◽  
Physical Model ◽  
Suspended Sediment ◽  
Development Trend ◽  
Jiangxi Province ◽  
Topographic Features ◽  
Deposition Area ◽  
Set Up ◽  
Deposition Test

Abstract To alleviate the problem that the water level drops more and more seriously in recent years, Jiangxi province proposes to set up regulation gates at each of the estuaries of Ganjiang River to raise the water level in Nanchang city during the dry season. The operation of this project will raise the upstream water level, which means the sediment transport rate will decrease and lead to deposition problems. In order to find out the deposition area and development trend, we carried out the suspended sediment deposition test on an existing physical model. The study shows that the upstream sediment is mainly deposited in the reaches near the two deltas. Some special topographic features are more likely to cause siltation, such as the wide and deep thalweg and the backflow areas at the downstream of convex banks. After the operation of the project, the erosion trend of the upper reaches of the central and southern branches will change to siltation, and the siltation of the upper reaches of the Western branch will be further strengthened. Fifteen years later, with the decrease of the upstream sediment intensity, the sediment siltation phenomenon will gradually move downstream, however, this will be a long process.

scholarly journals Numerical Investigation of a Flash Flood Process that Occurred in Zhongdu River, Sichuan, China

2021 ◽  
Vol 9 ◽  
Author(s):  
Qingyuan Yang ◽  
Tonghuan Liu ◽  
Jingjing Zhai ◽  
Xiekang Wang
Keyword(s):  
Sediment Transport ◽  
Water Level ◽  
Flash Flood ◽  
Peak Level ◽  
Field Studies ◽  
Bed Deformation ◽  
Bed Erosion ◽  
Set Up ◽  
Discharge Profile ◽  
The Impact

In 2018, a flash flood occurred in the Zhongdu river, which lies in Yibin, Sichuan province of China. The flood caused many casualties and significant damage to people living nearby. Due to the difficulty in predicting where and when flash floods will happen, it is nearly impossible to set up monitors in advance to detect the floods in detail. Field investigations are usually carried out to study the flood propagation and disaster-causing mechanism after the flood’s happening. The field studies take the relic left by the flash flood to deduce the peak level, peak discharge, bed erosion, etc. and further revel the mechanism between water and sediment transport during the flash flood This kind of relic-based study will generate bigger errors in regions with great bed deformation. In this study, we come up with numerical simulations to investigate the flash flood that happened in the Zhongdu river. The simulations are based on two-dimensional shallow water models coupled with sediment transport and bed deformation models. Based on the real water level and discharge profile measured by a hydrometric station nearby, the numerical simulation reproduced the flash flood in the valley. The results show the flood coverage, water level variation, and velocity distribution during the flood. The simulation offers great help in studying the damage-causing process. Furthermore, simulations without considering sediment transport are also carried out to study the impact of bed erosion and sedimentation. The study proved that, without considering bed deformation, the flood may be greatly underestimated, and the sediment lying in the valley has great impact on flood power.

scholarly journals 3D numerical modeling of flow and sediment transport in rivers and open channels

2019 ◽  
Vol 3 (1) ◽  
pp. 23-36
Author(s):  
Le Song Giang ◽  
Tran Thi My Hong
Keyword(s):  
Boundary Condition ◽  
Sediment Transport ◽  
Numerical Model ◽  
Differential Equations ◽  
Water Level ◽  
Suspended Sediment ◽  
Three Dimensional ◽  
River Bed ◽  
Suspended Sediment Concentrations ◽  
Flow And Sediment Transport

Numerical model is a useful tool in studying the flow and sediment transport, change in river bed and is built on solving governing differential equations. Numerical model has many different levels and three-dimensional model is the highest level, allowing detailed simulation of flow and sediment transport process in 3D space. The paper presents a method calculating three - dimensional flow and sediment transport in the open channel. Water level and flow velocity are solved from three-dimensional equations with hydrostatic hypothesis. Concentration of suspended sediment, bottom sediment and bottom evolution is solved from transport equations. The governing differential equations in the "sigma" transform coordinate system are solved by finite volume method on unstructured grid of quadrilateral elements. Boundary condition of water level or flow will be imposed on open boundary. For suspended sediment concentrations in the injected phase, suspended sediment concentrations are applied and the outflow phase applies free drainage conditions. This method of calculation was tested with the problem of curved channel sediment transport which was studied experimentally by Odgaard and Bergs. Calculation results are quite consistent with the measured data. In order to test the practical applicability, this method is also tested with the problem of sediment transport in Cu lao Pho islet on Dong Nai river. To solve the matter of hydraulic boundary condition of this problem, the model of Cu lao Pho islet is integrated into the Sai Gon - Dong Nai river system model. Results of the calculation of the river bed evolution of the Cu lao Pho islet on the Dong Nai river also show that this calculation method gives results consistent with the rule and can be used in practical research.  

scholarly journals Setting Up of an Experimental Site for the Continuous Monitoring of Water Discharge, Suspended Sediment Transport and Groundwater Levels in a Mediterranean Basin. Results of One Year of Activity

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3130
Author(s):  
Stefano Giorgio Pagano ◽  
Donato Sollitto ◽  
Marco Colucci ◽  
Davide Prato ◽  
Fabio Milillo ◽  
...  
Keyword(s):  
Surface Water ◽  
Sediment Transport ◽  
Suspended Sediment ◽  
Continuous Monitoring ◽  
Water Discharge ◽  
Suspended Sediment Transport ◽  
Flood Events ◽  
Experimental Site ◽  
Groundwater Levels ◽  
Set Up

The study of suspended sediment transport requires continuous measurement of water discharge to better understand the sediment dynamics. Furthermore, a groundwater monitoring network can support the stream discharge measures, as it reveals how the interactions between surface water and groundwater may affect runoff and consequently sediment transport during flood events. An experimental site for the continuous monitoring of water discharge, suspended sediment transport and groundwater levels was set up in the Carapellotto basin (27.17 km2), which is located in Apulia, Southern Italy. Seven flood events that occurred in the operation timespan were covered with a full record of both water discharge and sediment concentration. Some monitoring problems, largely due to the clogging of the float by mud, suggested to improve the experimental set up. The results show high values of suspended sediments concentration which indicate the sub-basin’s key role in the sediment delivery to the whole river system, while counter-clockwise hysteresis loops are the most frequent due to the basin characteristics. The effects of the interaction between surface water and groundwater are related not only to the flood magnitude but also to the hydrogeological features in the hyporheic zone.

scholarly journals Numerical Simulation of Flow and Suspended Sediment Transport in the Distributary Channel Networks

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Wei Zhang ◽  
Qiong Jia ◽  
Xiaowen Chen
Keyword(s):  
Sediment Transport ◽  
Water Level ◽  
Suspended Sediment ◽  
Suspended Sediment Concentration ◽  
Transport Model ◽  
Sediment Concentration ◽  
Suspended Sediment Transport ◽  
Governing Equations ◽  
Channel Networks ◽  
Distributary Channel

Flow and suspended sediment transport in distributary channel networks play an important role in the evolution of deltas and estuaries, as well as the coastal environment. In this study, a 1D flow and suspended sediment transport model is presented to simulate the hydrodynamics and suspended sediment transport in the distributary channel networks. The governing equations for river flow are the Saint-Venant equations and for suspended sediment transport are the nonequilibrium transport equations. The procedure of solving the governing equations is firstly to get the matrix form of the water level and suspended sediment concentration at all connected junctions by utilizing the transformation of the governing equations of the single channel. Secondly, the water level and suspended sediment concentration at all junctions can be obtained by solving these irregular spare matrix equations. Finally, the water level, discharge, and suspended sediment concentration at each river section can be calculated. The presented 1D flow and suspended sediment transport model has been applied to the Pearl River networks and can reproduce water levels, discharges, and suspended sediment concentration with good accuracy, indicating this that model can be used to simulate the hydrodynamics and suspended sediment concentration in the distributary channel networks.

scholarly journals A Coupled Model of the 1D River Network and 3D Estuary Based on Hydrodynamics and Suspended Sediment Simulation

2014 ◽  
Vol 2014 ◽  
pp. 1-13
Author(s):  
Wei Zhang ◽  
Shujie Lyu ◽  
Yuliang Zhu ◽  
Xiaowen Chen
Keyword(s):  
Sediment Transport ◽  
Water Level ◽  
Suspended Sediment ◽  
3D Model ◽  
Coupled Model ◽  
River Network ◽  
Suspended Sediment Transport ◽  
Wet Season ◽  
Two Systems ◽  
1D Model

River networks and estuaries are very common in coastal areas. Runoff from the upper stream interacts with tidal current from open sea in these two systems, leading to a complex hydrodynamics process. Therefore, it is necessary to consider the two systems as a whole to study the flow and suspended sediment transport. Firstly, a 1D model is established in the Pearl River network and a 3D model is applied in its estuary. As sufficient mass exchanges between the river network and its estuary, a strict mathematical relationship of water level at the interfaces can be adopted to couple the 1D model with the 3D model. By doing so, the coupled model does not need to have common nested grids. The river network exchanges the suspended sediment with its estuary by adding the continuity conditions at the interfaces. The coupled model is, respectively, calibrated in the dry season and the wet season. The results demonstrate that the coupled model works excellently in simulating water level and discharge. Although there are more errors in simulating suspended sediment concentration due to some reasons, the coupled model is still good enough to evaluate the suspended sediment transport in river network and estuary systems.

Underwater high-precision ultrasonic water level measurement method for hydraulic physical model

2020 ◽  
Vol 28 (9) ◽  
pp. 2027-2034
Author(s):  
Yue-jie SHU ◽  
◽  
Jun WU ◽  
Yuan-hang ZHOU ◽  
Yu-feng MA ◽  
...  
Keyword(s):  
Water Level ◽  
Physical Model ◽  
High Precision ◽  
Measurement Method ◽  
Level Measurement

2D and 3D CFD Investigations of Seabed Shear Stresses Around Subsea Pipelines

2013 ◽  
Author(s):  
Wenwen Shen ◽  
Terry Griffiths ◽  
Mengmeng Xu ◽  
Jeremy Leggoe
Keyword(s):  
Sediment Transport ◽  
Suspended Sediment ◽  
Interaction Model ◽  
Suspended Sediment Transport ◽  
Shear Stresses ◽  
Parametric Function ◽  
Ample Evidence ◽  
North West ◽  
Wide Range ◽  
Subsea Pipelines

For well over a decade it has been widely recognised that existing models and tools for subsea pipeline stability design fail to account for the fact that seabed soils tend to become mobile well before the onset of pipeline instability. Despite ample evidence obtained from both laboratory and field observations that sediment mobility has a key role to play in understanding pipeline/soil interaction, no models have been presented previously which account for the tripartite interaction between the fluid and the pipe, the fluid and the soil, and the pipe and the soil. There are numerous well developed and widely used theories available to model pipe-fluid and pipe-soil interactions. A challenge lies in the way to develop a satisfactory fluid-soil interaction algorithm that has the potential for broad implementation under both ambient and extreme sea conditions due to the complexity of flow in the vicinity of a seabed pipeline or cable. A widely used relationship by Shields [1] links the bedload and suspended sediment transport to the seabed shear stresses. This paper presents details of computational fluid dynamics (CFD) research which has been undertaken to investigate the variation of seabed shear stresses around subsea pipelines as a parametric function of pipeline spanning/embedment, trench configuration and wave/current properties using the commercial RANS-based software ANSYS Fluent. The modelling work has been undertaken for a wide range of seabed geometries, including cases in 3D to evaluate the effects of finite span length, span depth and flow attack angle on shear stresses. These seabed shear stresses have been analysed and used as the basis for predicting sediment transport within the Pipe-Soil-Fluid (PSF) Interaction Model [2] in determining the suspended sediment concentration and the advection velocity in the vicinity of pipelines. The model has significant potential to be of use to operators who struggle with conventional stabilisation techniques for the pipelines, such as those which cross Australia’s North West Shelf, where shallow water depths, highly variable calcareous soils and extreme metocean conditions driven by frequent tropical cyclones result in the requirement for expensive and logistically challenging secondary stabilisation measures.

Sign in / Sign up

Export Citation Format

Share Document