Application of a series scale model in channel regulation scour prevention of river reaches in the Yangtze estuary

2013 ◽  
Author(s):  
Hua Xu ◽  
Yunfeng Xia ◽  
Daowen Wu ◽  
Xiaojun Wang
Keyword(s):  
Yangtze Estuary ◽  
Scale Model ◽  
The Yangtze Estuary ◽  
Channel Regulation

ZOOPLANKTON DISTRIBUTION AND VARIATION IN THE YANGTZE ESTUARY AND ITS ADJACENT WATERS IN SUMMER AND AUTUMN

2010 ◽  
Vol 33 (6) ◽  
pp. 1219-1225 ◽  
Author(s):  
Fei-Yan ZHANG ◽  
Jing-Liang TANG ◽  
Dao-Ji LI ◽  
Tao FANG ◽  
Biao WANG
Keyword(s):  
Yangtze Estuary ◽  
The Yangtze Estuary ◽  
Zooplankton Distribution

Changes in blood moisture,osmolality and ion concentration of juvenile Chinese sturgeon(Acipenser sinensis)in the Yangtze Estuary

2013 ◽  
Vol 37 (12) ◽  
pp. 1795
Author(s):  
Feng ZHAO ◽  
Tao ZHANG ◽  
Junli HOU ◽  
Jianyi LIU ◽  
Longzhen ZHANG ◽  
...  
Keyword(s):  
Yangtze Estuary ◽  
Ion Concentration ◽  
Chinese Sturgeon ◽  
The Yangtze Estuary ◽  
Acipenser Sinensis

scholarly journals A Computationally Efficient Shallow Water Model for Mixed Cohesive and Non-Cohesive Sediment Transport in the Yangtze Estuary

Water ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1435
Author(s):  
Peng Hu ◽  
Junyu Tao ◽  
Aofei Ji ◽  
Wei Li ◽  
Zhiguo He
Keyword(s):  
Sediment Transport ◽  
Yangtze Estuary ◽  
Water Model ◽  
Cohesive Sediments ◽  
Shallow Water Model ◽  
Computationally Efficient ◽  
Time Step ◽  
The Yangtze Estuary ◽  
Erosion Coefficient ◽  
Cohesive Sediment Transport

In this paper, a computationally efficient shallow water model is developed for sediment transport in the Yangtze estuary by considering mixed cohesive and non-cohesive sediment transport. It is firstly shown that the model is capable of reproducing tidal-hydrodynamics in the estuarine region. Secondly, it is demonstrated that the observed temporal variation of suspended sediment concentration (SSC) for mixed cohesive and non-cohesive sediments can be well-captured by the model with calibrated parameters (i.e., critical shear stresses for erosion/deposition, erosion coefficient). Numerical comparative studies indicate that: (1) consideration of multiple sediment fraction (both cohesive and non-cohesive sediments) is important for accurate modeling of SSC in the Yangtze Estuary; (2) the critical shear stress and the erosion coefficient is shown to be site-dependent, for which intensive calibration may be required; and (3) the Deepwater Navigation Channel (DNC) project may lead to enhanced current velocity and thus reduced sediment deposition in the North Passage of the Yangtze Estuary. Finally, the implementation of the hybrid local time step/global maximum time step (LTS/GMaTS) (using LTS to update the hydro-sediment module but using GMaTS to update the morphodynamic module) can lead to a reduction of as high as 90% in the computational cost for the Yangtze Estuary. This advantage, along with its well-demonstrated quantitative accuracy, indicates that the present model should find wide applications in estuarine regions.

scholarly journals Ecological Degradation of the Yangtze and Nile Delta-Estuaries in Response to Dam Construction with Special Reference to Monsoonal and Arid Climate Settings

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1145
Author(s):  
Zhongyuan Chen ◽  
Hao Xu ◽  
Yanna Wang
Keyword(s):  
Regime Shift ◽  
Yangtze Estuary ◽  
Anthropogenic Sources ◽  
Arid Climate ◽  
Dam Construction ◽  
Nutrient Inputs ◽  
The Yangtze Estuary ◽  
Ecological Degradation ◽  
Phytoplankton Communities

This study reviews the monsoonal Yangtze and the arid Nile deltas with the objective of understanding how the process–response between river-basin modifications and delta-estuary ecological degradation are interrelated under contrasting hydroclimate dynamics. Our analysis shows that the Yangtze River had a long-term stepwise reduction in sediment and silicate fluxes to estuary due to dam construction since the 1960s, especially after the Three Gorges Dam (TGD) closed in 2003. By contrast, the Nile had a drastic reduction of sediment, freshwater, and silicate fluxes immediately after the construction of the Aswan High Dam (AHD) in 1964. Seasonal rainfall in the mid-lower Yangtze basin (below TGD) complemented riverine materials to its estuary, but little was available to the Nile coast below the AHD in the hyper-arid climate setting. Nitrogen (N) and phosphate (P) fluxes in both river basins have increased because of the overuse of N- and P-fertilizer, land-use changes, urbanization, and industrialization. Nutrient ratios (N:P:Si) in both delta-estuaries was greatly altered, i.e., Yangtze case: 75:1:946 (1960s–1970s), 86:1:272 (1980s–1990s) and 102:1:75 (2000s–2010s); and Nile case: 6:1:32 (1960s–1970s), 8:1:9 (1980s–1990s), and 45:1:22 (2013), in the context of the optimum of Redfield ratio (N:P:Si = 16:1:16). This led to an ecological regime shift evidenced by a long-term change in phytoplankton communities in the Yangtze estuary, where silicious algae tended to lose dominance since the end of the 1990s, when more toxic dinoflagellates began to emerge. In the Nile estuary, such a regime shift was indicated by the post-dam dramatic reduction in zooplankton standing crop and fish landings until the early 2000s when biological recovery occurred due to nutrient inputs from anthropogenic sources. Although the Yangtze had higher human impacts than the Nile in terms of population, industrialization, and fertilizer application, N concentrations in the Nile estuarine waters surpassed the Yangtze in recent decades. However, eutrophication in the Yangtze estuary is much more intensive than in the Nile, leading to the likelihood of its estuarine water becoming more acidic than ever before. Therefore, ecological degradation in both delta-estuaries does not follow a linear trajectory, due not only to different climate dynamics but also to human forcings. The comparative insights of this study should be incorporated into future integrated coastal management of these two important systems.

scholarly journals A study of in-situ sediment flocculation in the turbidity maxima of the Yangtze Estuary

2017 ◽  
Vol 191 ◽  
pp. 1-9 ◽  
Author(s):  
Chao Guo ◽  
Qing He ◽  
Leicheng Guo ◽  
Johan C. Winterwerp
Keyword(s):  
Yangtze Estuary ◽  
The Yangtze Estuary
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