Numerical study on the effect of edge scouring on stability of soft mattress in the Yangtze estuary

2021 ◽  
Author(s):  
Aofei Ji ◽  
Peng Hu ◽  
Zhiguo He ◽  
Fengfeng Gu
Keyword(s):  
Flow Structure ◽  
Numerical Study ◽  
Water Channel ◽  
River Estuary ◽  
Yangtze Estuary ◽  
Yangtze River Estuary ◽  
The Yangtze Estuary ◽  
Bed Erosion ◽  
Physically Based ◽  
Depth Increase

<p><strong>Abstract: </strong>In the Yangtze River Estuary deep-water channel regulation project, soft mattresses have been widely used to reduce bed erosion and thus improve stability of bridges/piers/levees/dikes. However, soft mattresses are also subject to failure due to the continuous and gradual scour in their edges, which have been a major risk for their stability. Here we report a preliminary numerical study on this issue. Firstly, a depth-averaged two-dimensional hydro-sediment-morphodynamic model is applied to simulate edge scour process for the submerged dike of the Jiangyanansha in the Yangtze estuary. For this purpose, physically-based sediment erosion parameterization is proposed to take account of the effect of the soft mattresses. Compared with the inner area of the soft mattress, only the edge area has stronger erodibility. Numerical comparative studies indicate that a scouring pit may develop to the vicinity of the submerged dike without the protection of the soft mattress, whereas under the protection of the soft mattress, the scouring pit can be largely controlled. Nevertheless, as the scouring process continues, the pit region and depth increase, which may finally lead to failure of the soft mattress. Finally, full 3D high-resolution simulations of the near-bed flow structure with/without edge scour are conducted using flow3D to shed light on the failure mechanisms of the soft mattresses.</p><p><strong>Keywords:</strong> submerged dikes, soft mattress, erodibility, Yangtze estuary, edge scour, flow structure</p>

Photobleaching of chromophoric dissolved organic matter (CDOM) in the Yangtze River estuary: kinetics and effects of temperature, pH, and salinity

2017 ◽  
Vol 19 (6) ◽  
pp. 861-873 ◽  
Author(s):  
Guisheng Song ◽  
Yijie Li ◽  
Suzheng Hu ◽  
Guiju Li ◽  
Ruihua Zhao ◽  
...  
Keyword(s):  
Organic Matter ◽  
Yangtze River ◽  
River Estuary ◽  
Yangtze Estuary ◽  
Chromophoric Dissolved Organic Matter ◽  
Yangtze River Estuary ◽  
The Yangtze River ◽  
The Yangtze Estuary ◽  
The Yangtze River Estuary ◽  
Effects Of Temperature

CDOM photobleaching in the Yangtze estuary is affected by its source, and water temperature and pH but not salinity.

scholarly journals Numerical Study on the Expansion and Variation of Changjiang Diluted Water in Summer and Autumn

2021 ◽  
Vol 9 (3) ◽  
pp. 317
Author(s):  
Wanli Hou ◽  
Menglin Ba ◽  
Jie Bai ◽  
Jianghua Yu
Keyword(s):  
Yangtze River ◽  
Sea Water ◽  
Numerical Study ◽  
River Estuary ◽  
Ocean Model ◽  
Theoretical Research ◽  
Yangtze River Estuary ◽  
Hydrodynamic Characteristics ◽  
Changjiang Diluted Water ◽  
Transportation Route

In view of the expansion and directional change mechanisms of Yangtze River water diluted with sea water in the shelf region (also known as Changjiang diluted water [CDW]) during summer and autumn, a three-dimensional hydrodynamic model of the Yangtze River Estuary (YRE) and its adjacent waters was established based on the Finite Volume Community Ocean Model (FVCOM). Compared with the measured data, the model accurately simulates the hydrodynamic characteristics of the YRE. On that basis, the influence of the expansion patterns of the CDW in both summer and autumn was studied. It was found that, in 2019, the CDW expanded to the northeast in the summer and to the southeast in the autumn, and that the route of the CDW is mainly controlled by the wind, not the runoff. Current seasonal winds also change the transportation route of the CDW by affecting its hydrodynamic field. Typhoons are frequent in both summer and autumn, causing abnormalities in both the transportation route and expansion of the CDW. During a typhoon, a large amount of the CDW is transported in a continuous and abnormal manner, accelerating the path turning of the CDW. This paper enhances the existing theoretical research of the CDW and provides a reference with respect to the expansion of diluted water all over the world.

Numerical study on the summertime patches of red tide in the adjacent sea of the Changjiang (Yangtze) River Estuary, China

2019 ◽  
Vol 143 ◽  
pp. 242-255 ◽  
Author(s):  
Dapeng Qu ◽  
Huaming Yu ◽  
Yuchen Sun ◽  
Yunxia Zhao ◽  
Qinsheng Wei ◽  
...  
Keyword(s):  
Yangtze River ◽  
Numerical Study ◽  
Red Tide ◽  
River Estuary ◽  
Yangtze River Estuary

Morphodynamic Simulation at the South Branch of Yangtze Estuary

2009 ◽  
Author(s):  
Xiaoyan Zhou ◽  
Ulrich Zanke ◽  
Yixin Yan ◽  
Jinhai Zheng
Keyword(s):  
Yangtze River ◽  
Morphological Changes ◽  
River Estuary ◽  
Wave Model ◽  
Yangtze Estuary ◽  
Yangtze River Estuary ◽  
The Yangtze River ◽  
The South ◽  
Morphological Response ◽  
The Yangtze River Estuary

In this paper a numerical morphodynamic model TIMOR3 has been introduced and applied to simulate the morphological response to the water and sediment changes in the Yangtze River Estuary. TIMOR3, coupled with Hydrodynamic Model and Wave Model, is used to simulate a long-term and huge area of the morphological changes in the Yangtze River Estuary. A detailed investigation was made to the south branch where the Deepwater Channel Navigation Project is under construction. The effect of the project in different phases with different water depth has been simulated and analyzed.

scholarly journals Characteristics and source tracing of organic carbon in intertidal sediments of wetland in Yangtze Estuary, China

2020 ◽  
Author(s):  
Haiyan Yu ◽  
Weiwei Li ◽  
Changxu Han ◽  
Han Fang ◽  
Xingquan Shu ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Cycle ◽  
Global Climate ◽  
Stable Carbon Isotope ◽  
River Estuary ◽  
Suspended Particles ◽  
Mean Value ◽  
Yangtze Estuary ◽  
Yangtze River Estuary ◽  
Marsh Vegetation

Abstract Background: Wetland ecosystem is characterized by water-land interaction and plays an important role in regional energy and material circulation. In the context of global climate change, the study of wetland carbon storage and carbon cycle has become a focus of academic attention. The characteristics of organic carbon in sediments and its source is a key problem in the study of carbon cycle in wetlands. Results: In this study, the characteristics of total organic carbon (TOC), total nitrogen (TN) accumulation, and stable carbon isotope (δ13C) in the vegetation and soil were investigated for the three dominant salt marsh vegetation Phragmites australis (PA), Spartina alterniflora (SA), Scirpus mariqueter (SM) of the coastal wetlands of Chongming Dongtan in the Yangtze River Estuary. The results showed that the mean value of TOC and TN concentrations in the surface sediments of wetland were 1.39 ± 0.34% and 0.091± 0.024%, respectively. The carbon stable isotope (δ13C) mean value of sediment was -24.17±1.51‰. The TOC of the sediment in the three saltmarsh plant communities was in the order of SA (1.76 ± 0.38%) > PA (1.45 ± 0.37%) > SM (0.96 ± 0.44%). The simulation results of the three end-member mixing equations showed that the organic carbon in sediments was mainly derived from suspended particles (42.44 ± 20.89%) and vegetation (34.50 ± 25.23%). The contribution rate of microalgae is lower (23.06 ± 4.62%). Conclusion: The organic carbon in sediments of wetland in Yangtze Estuary are the result of mixed input of terrestrial organic carbon and marine organic carbon. Organic carbon in sediments was mainly derived from suspended particles and vegetations. The results provide preliminary knowledge of the distribution and sources of sedimentary organic carbon for better understanding the sediment transport and deposition in this region.

A New Kind of Channel-"Tidal Reversible Channel": Primary Design and Feasibility Analysis

2013 ◽  
Vol 361-363 ◽  
pp. 1992-1997
Author(s):  
Ting Ting Chen ◽  
Chao Jian Shi ◽  
Qin Lei ◽  
Jin Biao Chen
Keyword(s):  
Yangtze River ◽  
Heavy Traffic ◽  
Water Channel ◽  
River Estuary ◽  
Feasibility Analysis ◽  
Yangtze River Estuary ◽  
Peak Period ◽  
Research Directions ◽  
Key Points ◽  
Dynamic Time

A new kind of traffic separation mode for the two-way channel was proposed primarily by extending the channel to left for the heavy traffic side during the peak period, forming a new kind of channel--Tidal Reversible Channel. This method can improve the general navigation efficiency and meet the navigation demands of both sides of the channel at the same time. The two key points of the reversible channel which are the operation occasion and the reversible width of the channel, called Dynamic Time and Dynamic Zone, were discussed, also their further research directions. Then, the feasibility of the new channel was verified by two different design ships in Yangtze River Estuary Deep-Water Channel, indicating that the reversible channel will have wide study and application prospect.

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