Analysis of Hydrodynamic Characteristics of Semi-Enclosed Harbors—a Cause Study of Xiangzhou Port by YANG Yugui, XUAN Xiaoming, LIU Guozhen, TONG Xiaolei, YUAN Fei

“…Affected by the construction of a series of projects,the semi-enclosed harbor often appears the phenomenon of weakening hydrodynamic force and worsening water exchange.In order to study the impact of project construction on the hydrodynamic environment of semi-closed harbors,a typical semi-enclosed port,namely Xiangzhou Fishing Port,in the Pearl River Estuary was taken as an example,and the impact of detailed control planning of the surrounding areas on flood discharge,tidal influx,and water exchange in Xiangzhou Fishing Port was studied.The results show that after the implementation of the planning scheme,the water level of the water area near the planning area and the upstream entrance gate,as well as the tidal volume of the tidal channel on the west side of Lingdingyang change slightly,but the tidal volume in the area of Xiangzhou Port decreases by about 1%.The hydrodynamic force is further weakened,and the semi-exchange cycle of the water body increases by about 3.2%.In particular,the water exchange capacity in the northwest corner of the port area is relatively poor,which is unfavorable to the water environment for a long time,and it is necessary to take hydrodynamic enhancement measures.The research results can provide a reference for hydrodynamic improvement in the water area of Xiangzhou Port.…”
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The Impact of Breakwater Type on Hydrodynamic Environment in Semi-Closed Harbor by WU Qiong, LI Mugui, LUO Huan

“…Affected by breakwater construction,the water exchange of semi-closed harbor is often not smooth,and the self-purification ability is weak.To study the influence of different types of breakwater on the hydrodynamic environment in semi-closed harbor,the article took a typical semi-enclosed port in the Pearl River estuary,Xiangzhou fishing port as an example to analyze the differences of water exchange ability and the transport law of pollutants under the layout scheme of breakwater with opening width including 20、40、60、100 m.The results showed that,compared with the fully closed breakwater scheme,under the scheme of opening width of 20、40、60、100 m,the half exchange period of water in the harbor increased by 5.0 hours,11.0 hours,14.0 hours and 14.5 hours.The scheme with opening more than 40m was better than 20 m.However,there was no significant difference in the effect of the three schemes of opening 40、60、100 m.Considering the influence of regional pollution source input,under the scheme of breakwater opening,the concentration of inorganic nitrogen increased by 0.2~0.4 mg/L in the area near the opening.It further aggravated the pressure of inorganic nitrogen pollution in the northern part of the harbor,while the quality of water environment in the southern part of the harbor was improved due to the enhancement of water exchange ability.…”
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Research Progress and Prospect of Extreme Water Increase by Storm Surge in Estuaries — A Case Study of Guangdong-Hong Kong-Macao Greater Bay Area by LIU Yuexuan, LI Huijing, LI Lanbin, LIU Xiaojian

“…Significant increases in water and extreme tide levels caused by typhoon storm surges are the primary threat to flood safety in estuarine areas,and are also the main cause of major natural disaster losses in the Guangdong-Hong Kong-Macao Greater Bay Area in recent years.This paper reveals the evolution patterns of water increase in storm surges over the years and introduces corresponding research methods.Meanwhile,it systematically reviews research achievements on the formation mechanism of extreme tide levels in storm surges from both foreign and domestic perspectives.Combined calculation models of extreme tide levels formed by astronomical tides and storm surges in China and abroad are also summarized,with a focus on achievements in dynamic mechanisms during extreme water increase in storm surges.Additionally,a two-dimensional nested mathematical model of storm surges in the South China Sea and the Pearl River Estuary is built,and the most unfavorable typhoon intensity and path are designed.The maximum water increase distribution in the Guangdong-Hong Kong-Macao Greater Bay Area is preliminarily simulated and obtained.Finally,it is urgent to put forward a set of safe,concise,and applicable formula for calculating the extreme tide levels of storm surges as soon as possible based on the understanding of the physical mechanism of the interaction between astronomical tides and storm surges.…”
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Numerical Study on the Behavior of Square Stiffened Caissons Penetrating into Normally Consolidated Clay by Wei Liu, Zhihuai Huang, Mi Zhou

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Analysis of the Impact of Sewage Outfall on the Water Quality of Coastal Waters of Macau Based on MIKE21 Model by CHANG Ze, ZHANG Qionghai, JIANG Yu, SUN Ning, HE Rui, WANG Tengfei, WU Yaju, LONG Xiaofei

“…This paper simulates the impact of the sewage outfall of the Macau Taipa Wastewater Treatment Plant on the water quality changes in the nearby Lingding Ocean by the hydrodynamic module (HD) and the transmission diffusion module (TR) of the MIKE21 model,provides the boundary conditions for the local two-dimensional tidal current model (built by MIKE21) through the one and two-dimensional integrated tidal current model of the Pearl River Estuary area,and analyzes the impact of pollutant diffusion under normal discharge and accident discharge in terms of the three evaluation factors,namely COD_Cr (chemical oxygen demand),SS (total suspended solids) and NH₃-N (Ammonia-Nitrogen),under the “2005·6” flood combination and “2001·2” low water combination as the most unfavorable hydrological conditions.The results show that the water quality of main channel can meet the Class Ⅲ standard among the Sea Water Quality Standards (GB 3097—1997).With proper preventive measure,the out-of-limit water area under accidental discharge is less than 0.2 km².This model has good adaptability to the simulation of the diffusion of pollutants into the coastal waters of Macau,so it can better simulate the impact of sewage discharge on the water quality of the sea under the action of ocean tides,and serve as a basis and research direction for the establishment of sewage outfall.…”
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Temporal and Spatial Distribution Characteristics of Rainstorm in China Based on CMORPH Integrated Precipitation by ZHAO Zixi, CHEN Zhihe

“…Based on the data set of China automatic station and CMORPH precipitation product fusion grid,this paper analyzes the spatial-temporal distribution characteristics and change trend of rainstorm number and rainstorm amount in 2008—2016 in China by the methods of rainfall object identification and Theil-Sen estimator.The research shows that there are 24 676 rainstorms in 2008—2016,including 20 135 small rainstorms,4 230 heavy rainstorms and 311 extremely heavy rainstorms.The rainstorm events in the whole year are at most in 2012 and at least in 2011with only 42,which occur frequently from May to September,accounting for 80.8% of the whole year.In 2010,2012 and 2014,the rainstorms in the coastal areas of South China and North China accounted for a relatively high proportion,some of which reached more than 60%.In 2008,2013 and 2016,the rainstorms in the coastal areas of South China and Hubei accounted for a relatively high proportion.From May to September,the rainstorm in China is widely distributed with large amount,mainly in the Pearl River Estuary,Northeast Jiangxi,and coastal areas of Hainan,Taiwan,Zhejiang and Fujian,with an annual average monthly rainstorm of about 150 mm.The number and amount of rainstorms are decreasing from the southeast coast to the northwest inland,with high value areas mainly in South China and the middle and lower reaches of the Yangtze River.The distribution of small rainstorms is similar to that of the total rainstorms.The heavy rainstorms are mainly concentrated in the coastal areas of Guangdong and Guangxi,the eastern Hainan and the southern Taiwan.Extremely heavy rainstorms are scattered in Southeast China.In the past 9 years,the number of rainstorms has increased,especially in South China and the middle and lower reaches of the Yangtze River,with significantly increased amount.…”
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Simulation and Strategy for Salinity Control Scheduling in Dongjiang Delta of Pearl River Basin in Severe Drought Year by LIN Zhongyuan, TANG Qi, WANG Fengen, XU Wei, HUANG Pengfei, ZOU Huazhi

“…In recent years, the saltwater intrusion in the Pearl River Estuary has intensified, with a significantly expanded impact range. …”
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Temporal and Spatial Characteristics of Tidal Current in the Eastern Waters of Macao in Summer by FANG Shenguang, HUANG Chunhua, YU Fenghua, WANG Shijun, HE Yong

“…The eastern waters of Macao at the Pearl River Estuary are an important channel for water and sediment discharged by the west beach of Lingdingyang Estuary and Macao waterway.The measured data during the flood seasons shows that the waters feature semi-diurnal tidal currents,and the average velocity in this area is about 21~23 cm/s during the flood and 18~29 cm/s during the ebb.The flowing direction is stable,namely,N—NNW trending during the flood and S trending during the ebb,and tidal power is stronger in the south.The average velocity in the waters is mainly dependent on the tidal type,and the flood runoff mainly affects residual currents and tidal duration.A stagnant area is formed in the north of the waters during the flood,and the water and sediment in the south are transported outside the Lingdingyang Estuary.Wind on the sea surface has a significant impact on the vertical dynamic structure of flow in the range of 40% water depth,and residual flow direction in the range of 10% water depth near the sea surface has a good follow-up.During southwest wind,the maximum horizontal flow velocity gradient appears in the second flood and ebb stage and corresponds to the occurrence of the maximum sediment concentration in the tidal cycle.Due to the shallow water depth in the north of the waters,the bed shear gradient force is generally greater than that in the south.As a result,the sediment concentration observed in the north of the waters is significantly higher than that in the southeast.According to the comprehensive analysis,astronomical tides,flood runoff,and wind are the main controlling dynamic factors in the waters.The friction resistance of shallow water in the north is drastically larger than that in the south,which leads to a significant difference in tidal duration and phases of vertical floods and ebbs.As a consequence,the special vertical dynamic structure of convergence on the surface and dispersion at the bottom is formed in the waters,which is strengthened by massive freshwater runoffs during the flood seasons.This leads to the trend of surface diluted water drifting to the east and the invasion of the nearshore by bottom high-salt water.…”
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Spatiotemporal occurrence, distribution, and risk of steroid hormones along the coast of Guangdong, China by Xing Zhao, Xing Zhao, Yunlin Jiang, Hanqiang Deng, Yao Lu, Suimin Li, Yuxia Jiang, Kaifeng Sun

“…The concentrations of steroid hormones in Guanghai Bay, the Pearl River Estuary, Daya Bay, and Zhelin Bay were significantly higher than those in other bays.DiscussionNegative correlations were observed between steroid hormones and salinity, indicating a potential continental input. …”
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