Numerical Analysis of the Influence of Saltwater Intrusion on the Deepwater Channel in the Changjiang Estuary

2012 ◽  
Vol 204-208 ◽  
pp. 2352-2356
Author(s):  
Jie Gu ◽  
Xin Qin ◽  
Wei Chen ◽  
Dan Qing Ma ◽  
Xiao Li Wang
Keyword(s):  
Saltwater Intrusion ◽  
Current Model ◽  
River Estuary ◽  
Changjiang Estuary ◽  
Wet Season ◽  
The Changjiang Estuary ◽  
Velocity Magnitude ◽  
Negative Effect ◽  
Fine Suspended Sediment ◽  
Deepwater Channel

Since 2005, the increased quantity of back silting in the Deepwater Channel has a negative effect on shipping. This research sets up a 2D current model for the Changjiang River estuary using Delft3D-FLOW. The model is well calibrated and verified by applying the observed data of tidal levels and velocities, i.e. the water level, flow velocity magnitude and direction computed from the model agree well with the real measured data. In order to explore the influence of saltwater intrusion on the Deepwater Channel in the Changjiang Estuary, the computed velocity along the Deepwater Channel, the horizontal and longitudinal salinity distribution in the Deepwater Channel in the dry and wet season are analyzed. Analyzed results show that the fine suspended sediment flocculates easily in the upper reach of the Deepwater Channel beyond Hengsha Island in dry season, which increases sediment’s falling and deposition in this region.

scholarly journals Impacts of topography change on saltwater intrusion over the past decade in the Changjiang Estuary

2019 ◽  
Vol 231 ◽  
pp. 106469 ◽  
Author(s):  
Qing Chen ◽  
Jianrong Zhu ◽  
Hanghang Lyu ◽  
Shunqi Pan ◽  
Shenliang Chen
Keyword(s):  
Saltwater Intrusion ◽  
Changjiang Estuary ◽  
The Changjiang Estuary ◽  
The Past

Types of saltwater intrusion of the Changjiang Estuary

2001 ◽  
Vol 44 (S1) ◽  
pp. 150-157 ◽  
Author(s):  
Zhichang Mao ◽  
Huanting Shen ◽  
T. James Liu ◽  
D. Eisma
Keyword(s):  
Saltwater Intrusion ◽  
Changjiang Estuary ◽  
The Changjiang Estuary

scholarly journals Impacts of the Qingcaosha Reservoir on saltwater intrusion in the Changjiang Estuary

2021 ◽  
Vol 4 (1) ◽  
pp. 17-35
Author(s):  
Zhangliang Ding ◽  
Jianrong Zhu ◽  
Hanghang Lyu
Keyword(s):  
Saltwater Intrusion ◽  
Neap Tide ◽  
Spring Tide ◽  
Changjiang Estuary ◽  
Water Diversion ◽  
The Changjiang Estuary ◽  
The North ◽  
Salinity Increase ◽  
Hydrodynamic Processes ◽  
Changxing Island

The massive Qingcaosha Reservoir (QCSR) is located in the Changjiang Estuary along the northwest coast of Changxing Island. The reservoir significantly narrowed the upper reaches of the North Channel and deepened the channel near the reservoir. These topographical changes inevitably influenced hydrodynamic processes and saltwater intrusion in the estuary. A well-validated model was employed to investigate the influence of the QCSR on saltwater intrusion in the Changjiang Estuary. The model results showed that the narrowed upper reaches of the North Channel decreased the water diversion ratio and thus increased salinity in the North Channel. During the moderate tide after neap tide, the salinity decreased at the water intake of the QCSR because saltwater intrusion was obstructed at flood slack at the surface, while the salinity increase during the moderate tide after spring tide was mainly due to the intensified saltwater intrusion during spring tide. The deepening of the channel near the QCSR resulted in an increased water diversion ratio, and the salinity in the Eastern Chongming Shoal decreased by more than 0.5 psu during spring tide; however, the saltwater intrusion was enhanced due to the strengthened baroclinic force, which is proportional to the water depth. During neap tide, the salinity in the entire North Channel decreased because of a 1.4% increase in the water diversion ratio of the North Channel and the relatively weak tide.

scholarly journals Dynamic mechanism of an extremely severe saltwater intrusion in the Changjiang estuary in February 2014

2020 ◽  
Vol 24 (10) ◽  
pp. 5043-5056
Author(s):  
Jianrong Zhu ◽  
Xinyue Cheng ◽  
Linjiang Li ◽  
Hui Wu ◽  
Jinghua Gu ◽  
...  
Keyword(s):  
Water Level ◽  
Water Transport ◽  
River Discharge ◽  
Saltwater Intrusion ◽  
Changjiang Estuary ◽  
Maximum Speed ◽  
Residual Water ◽  
Northerly Wind ◽  
The Changjiang Estuary ◽  
Water Level Rise

Abstract. Estuarine saltwater intrusions are mainly controlled by river discharge and tides. Unexpectedly, an extremely severe saltwater intrusion event occurred in February 2014 in the Changjiang estuary under normal river discharge conditions. This intrusion cut off the freshwater input for 23 d into the Qingcaosha reservoir, which is the largest estuarine reservoir in the world, creating a severe threat to water safety in Shanghai. No similar catastrophic saltwater intrusion has occurred since records of salinity in the estuary have been kept. During the event, a persistent and strong northerly wind existed, with a maximum speed of 17.6 m s−1, lasting 9 d and coinciding with a distinct water level rise. Our study demonstrates that the extremely severe saltwater intrusion was caused by this northerly wind, which drove substantial landward net water transport to form a horizontal estuarine circulation that flowed into the northern channel and out of the southern channel. This landward net water transport overpowered the seaward-flowing river runoff and transported a large volume of highly saline water into the northern channel. The mechanisms of this severe saltwater intrusion event, including the northerly wind, residual water level rise, landward water transport and resulting horizontal circulation, etc., were systematically investigated.

scholarly journals IMPACTS OF DEEP WATERWAY PROJECT ON LOCAL CIRCULATIONS AND SALINITY IN THE CHANGJIANG ESTUARY, CHINA

2011 ◽  
Vol 1 (32) ◽  
pp. 44 ◽  
Author(s):  
Jianzhong Ge ◽  
Pingxing Ding ◽  
Changsheng Chen
Keyword(s):  
Saltwater Intrusion ◽  
Unstructured Grid ◽  
Model Simulation ◽  
High Tide ◽  
Changjiang Estuary ◽  
Observation Data ◽  
Three Dimension ◽  
Local Circulation ◽  
The Changjiang Estuary ◽  
Astronomical Tide

With an aim to improve and maintenance water depth along the navigational channel, the Deep Waterway Project has been conducted in the Changjiang Estuary. The structures of dikes and groins have greatly changed the local circulation with the combined effects of astronomical tide and strong freshwater discharge. A high-resolution fully three-dimension unstructured-grid model (FVCOM) has been applied to study the complicated hydrodynamics with the implementation of unstructured-grid dike-groin module. With the model validation with observation data, the simulation shows the dikes and groins has converted the rotational current into reciprocating flow along the navigational channel between the dikes, and produced the geometrically controlled eddies. The significant southward crossover current was produced along the dike during high tide when the water level is higher than the dike height. The strong saltwater intrusion is also revealed in the observation and model simulation.

scholarly journals Nitrous oxide in the Changjiang (Yangtze River) Estuary and its adjacent marine area: Riverine input, sediment release and atmospheric fluxes

2010 ◽  
Vol 7 (11) ◽  
pp. 3505-3516 ◽  
Author(s):  
G.-L. Zhang ◽  
J. Zhang ◽  
S.-M. Liu ◽  
J.-L. Ren ◽  
Y.-C. Zhao
Keyword(s):  
Nitrous Oxide ◽  
Yangtze River ◽  
River Estuary ◽  
N2o Emission ◽  
Changjiang Estuary ◽  
Yangtze River Estuary ◽  
Emission Rates ◽  
The Changjiang Estuary ◽  
Marine Area ◽  
Key Factor

Abstract. Dissolved nitrous oxide (N2O) was measured in the waters of the Changjiang (Yangtze River) Estuary and its adjacent marine area during five surveys covering the period of 2002–2006. Dissolved N2O concentrations ranged from 6.04 to 21.3 nM, and indicate great temporal and spatial variations. Distribution of N2O in the Changjiang Estuary was influenced by multiple factors and the key factor varied between cruises. Dissolved riverine N2O was observed monthly at station Xuliujing of the Changjiang, and ranged from 12.4 to 33.3 nM with an average of 19.4 ± 7.3 nM. N2O concentrations in the river waters showed obvious seasonal variations with higher values occurring in both summer and winter. Annual input of N2O from the Changjiang to the estuary was estimated to be 15.0 × 106 mol/yr. N2O emission rates from the sediments of the Changjiang Estuary in spring ranged from −1.88 to 2.02 μmol m−2 d−1, which suggests that sediment can act as either a source or a sink of N2O in the Changjiang Estuary. Average annual sea-to-air N2O fluxes from the studied area were estimated to be 7.7 ± 5.5, 15.1 ± 10.8 and 17.0 ± 12.6 μmol m−2d−1 using LM86, W92 and RC01 relationships, respectively. Hence the Changjiang Estuary and its adjacent marine area are a net source of atmospheric N2O.

scholarly journals Nitrous oxide in the Changjiang (Yangtze River) Estuary and its adjacent marine area: riverine input, sediment release and atmospheric fluxes

2010 ◽  
Vol 7 (3) ◽  
pp. 3125-3151 ◽  
Author(s):  
G.-L. Zhang ◽  
J. Zhang ◽  
S.-M. Liu ◽  
J.-L. Ren ◽  
Y.-C. Zhao
Keyword(s):  
Nitrous Oxide ◽  
Yangtze River ◽  
River Estuary ◽  
Changjiang Estuary ◽  
Yangtze River Estuary ◽  
Adjacent Area ◽  
Emission Rates ◽  
The Changjiang Estuary ◽  
Marine Area ◽  
N2o Fluxes

Abstract. Dissolved nitrous oxide (N2O) was measured in the waters of the Changjiang (Yangtze River) Estuary and its adjacent marine area during five surveys covering the period of 2002–2006. Dissolved N2O concentrations ranged from 6.04 to 21.3 nM, and indicate seasonal variations with high values occurring in summer and spring. Dissolved riverine N2O was observed monthly at station Xuliujing of the Changjiang, and ranged from 12.4 to 33.3 nM with an average of 20.8±7.8 nM. The average annual input of N2O from the Changjiang to the estuary and its adjacent area was estimated to be 15.8×106 mol/yr. N2O emission rates from the sediments of the Changjiang Estuary in spring ranged from −1.88 to 2.02 μmol m−2 d−1, which suggest that sediment can act as either a source or a sink of N2O in the Changjiang Estuary. The annual sea to air N2O fluxes from the Changjiang Estuary were estimated to be 6.8±3.7, 13.3±7.2 and 14.9±8.3 μmol m−2 d−1 using LM86, W92 and RC01 relationships, respectively. The annual sea to air N2O fluxes from the adjacent marine area were estimated to be 8.5±7.8, 15.3±13.5 and 17.4&plusmn15.7 μmol m−2 d−1 using LM86, W92 and RC01 relationship, respectively. Hence the Changjiang Estuary and its adjacent marine area is a net source of atmospheric N2O.

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