Net Bottom Sediment Transport Pattern Related to Residual Currents in the Pearl River Estuary, South China

Author(s):  
Yao Wu ◽  
Wei Zhang ◽  
Mingkai Guan ◽  
Huanghao Hu

In this study, the net bottom sediment transport pattern is measured and compared with flow pattern in the Pearl River Estuary (PRE). Based on 106 bottom sediment samples taken from the PRE, the spatial distribution of bottom sediment of mean grain size μ (mm), sorting coefficient σ, and skewness SK is calculated. Then the grain size trend analysis (GSTA) was used to detect the net bottom sediment transport characteristics. The bottom sediment is transported southward and southeastward in the upper part of the estuary and northward in the lower part, while a clockwise rotation trend occurs in the central part. Furthermore, a numerical flow model, based on Princeton Ocean Model (POM), is used to modulate the hydrodynamic conditions in the PRE. The simulated long-term bottom residual currents correlate well with the GSTA results, implying that the net bottom sediment transport is mainly controlled by the residual currents.

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 646 ◽  
Author(s):  
Jie Chen ◽  
Changbo Jiang ◽  
Zhiyuan Wu ◽  
Yuannan Long ◽  
Bin Deng ◽  
...  

Typhoons are major marine dynamic disasters that affect the coastal ocean areas of China. During a typhoon, the coupling dynamic factors, such as wind, waves, storm surges, and river runoff, greatly enhance the mass and energy exchange at the various interfaces of the ocean. A fully coupled atmosphere-wave-ocean model in the South China Sea (SCS) was established based on the WRF, SWAN, and ROMS models. The variation of sea surface salinity (SSS) and ocean subsurface salinity caused by Typhoon Kai-tak (201213) was analyzed by the fully coupled model, and the basic characteristics of the response of the upper ocean to the typhoon are given in this paper. The simulation results demonstrate that the salinity of the sea surface showed a sharp change during Typhoon Kai-tak, and it changed gradually after entering the recovery period. During the passage of Typhoon Kai-tak, the disturbance caused by strong winds strengthened the mixing process of the water in the Pearl River Estuary (PRE) and its adjacent waters. As the typhoon developed, under the influence of Ekman pumping, the mixing effect between the subsurface and the bottom and the upper water was obvious. Before the impact of Typhoon Kai-tak, the salinity had obvious stratification characteristics along the water depth. Due to the influence of the storm surge, the surface water with increased salinity was transported to the estuary, which led to an increase in the salinity of the estuary’s surface water. In this condition, it is highly likely for there to be saltwater intrusion. The salinity distribution characteristics of three schemes (ROMS model only, coupled WRF-ROMS model, and fully coupled WRF-SWAN-ROMS model) were compared in this study. In the fully coupled WRF-SWAN-ROMS model, the disturbance of the bottom water was the most obvious, and the salinity value was greater than that of the coupled WRF-ROMS model, which indicates that under the influence of waves, the mixing and exchange abilities were strengthened.


2014 ◽  
Vol 81 (2) ◽  
pp. 240-250 ◽  
Author(s):  
Qingyun Nan ◽  
Tiegang Li ◽  
Jinxia Chen ◽  
Rajiv Nigma ◽  
Xinke Yu ◽  
...  

AbstractA sediment core from the Pearl River Estuary (PRE) was analyzed for grain size and organic geochemistry parameters (TOC and δ13Corg). The results showed that high mean grain-size value and increased sand content were correlated with the high TOC and negative δ13Corg. These results indicated high river runoff in the PRE area. Peak river discharge occurred during the periods 1900–1750, 1500–1600, 1400–1200, 1000–900 and 750–600 cal yr BP. The main changes recorded in grain-size distributions, TOC contents, and δ13Corg variations appear to be directly related to monsoon precipitation in the sediment source area. An increased East Asian summer monsoon rainfall (EASM) and/or an enhanced East Asian winter monsoon rainfall could result in the increasing of monsoon rainfall. Typhoon related rainfalls could act as positive influence on precipitation levels. The study of the correlations between the rainfall records and ENSO activities revealed a close relationship between the monsoon rainfall in the PRE and the tropical Pacific variations. The frequent occurrence of ENSO might result in the southern migration of the EASM rain belt and lead to more typhoon-derived rainfall in the PRD during the late Holocene.


2019 ◽  
Vol 29 (4) ◽  
pp. 861-875
Author(s):  
Zeyu Zeng ◽  
William W. L. Cheung ◽  
Shiyu Li ◽  
Jiatang Hu ◽  
Ying Wang

2021 ◽  
Vol 9 (2) ◽  
pp. 131
Author(s):  
Dongliang Wang ◽  
Lijun Yao ◽  
Jing Yu ◽  
Pimao Chen

The Pearl River Estuary (PRE) is one of the major fishing grounds for the squid Uroteuthis chinensis. Taking that into consideration, this study analyzes the environmental effects on the spatiotemporal variability of U. chinensis in the PRE, on the basis of the Generalized Additive Model (GAM) and Clustering Fishing Tactics (CFT), using satellite and in situ observations. Results show that 63.1% of the total variation in U. chinensis Catch Per Unit Effort (CPUE) in the PRE could be explained by looking into outside factors. The most important one was the interaction of sea surface temperature (SST) and month, with a contribution of 26.7%, followed by the interaction effect of depth and month, fishermen’s fishing tactics, sea surface salinity (SSS), chlorophyll a concentration (Chl a), and year, with contributions of 12.8%, 8.5%, 7.7%, 4.0%, and 3.1%, respectively. In summary, U. chinensis in the PRE was mainly distributed over areas with an SST of 22–29 °C, SSS of 32.5–34‰, Chl a of 0–0.3 mg × m−3, and water depth of 40–140 m. The distribution of U. chinensis in the PRE was affected by the western Guangdong coastal current, distribution of marine primary productivity, and variation of habitat conditions. Lower stock of U. chinensis in the PRE was connected with La Niña in 2008.


Harmful Algae ◽  
2012 ◽  
Vol 13 ◽  
pp. 10-19 ◽  
Author(s):  
Ping-Ping Shen ◽  
Ya-Nan Li ◽  
Yu-Zao Qi ◽  
Lv-Ping Zhang ◽  
Ye-Hui Tan ◽  
...  

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