Stability of the Stratification of Water Bodies in the North Passage of the Yangtze River Estuary Based on the EFDC Model

To study the stratified stability of a water column in the North Passage of the Yangtze River Estuary,a numerical model of the hydrodynamics of this estuary is established using the EFDC model.On the basis of EFDC results,this paper derives and pro-vides the discriminative index of water body stability caused by salinity and analyzes the along-range variation in water body strati-fication stability in the North Passage of the Yangtze River Estuary and the periodic variation at a key location(bend area)based on the simulation results of the numerical model.This work shows that the water body in the bend area varies between mixed and strati-fied types,and the vertical average flow velocity has a good negative correlation with the differential velocity between the surface and bottom layers of the water body.The model simulation results validate the formulae for the stratified stability discriminant during spring tides.

Inter-annual variations of dissolved oxygen and hypoxia off the northern Changjiang River(Yangtze River) Estuary in summer from 1997 to 2014

Hypoxia off the Changjiang River Estuary has been the subject of much attention,yet systematic observations have been lacking,resulting in a lack of knowledge regarding its long-term change and drivers.By revisiting the repeated surveys of dissolved oxygen(DO) and other relevant hydrographic parameters along the section from the Changjiang River Estuary to the Jeju-do in the summer from 1997 to 2014,rather different trends were revealed for the dual low-DO cores.The nearshore low-DO core,located close to the river mouth and relatively stable,shows that hypoxia has become more severe with the lowest DO descen ding at a rate of -0.07 mg/(L·a) and the thickness of low-DO zone rising at a rate of 0.43 m/a.The offshore core,centered around 40-m isobath but moving back and forth between 123.5°-125°E,shows large fluctuations in the minimum DO concentration,with the thickness of low-DO zone falling at a rate of -1.55 m/a.The probable factors affecting the minimum DO concentration in the two regions also vary.In the nearshore region,the decreasing minimum DO is driven by the increase in both stratification and primary productivity,with the enhanced extension of the Changjiang River Diluted Water(CDW) strengthening stratification.In the offshore region,the fluctuating trend of the minimum DO concentration indicates that both DO loss and DO supplement are distinct.The DO loss is primarily attributed to bottom apparent oxygen utilization caused by the organic matter decay and is also relevant to the advection of low-DO water from the nearshore region.The DO supplement is primarily due to weakened stratification.Our analysis also shows that the minimum DO concentration in the nearshore region was extremely low in 1998,2003,2007 and 2010,related to El Ni?o signal in these summers.

Late Mesozoic Exhumation of the Huangling Massif:Constraints on the Evolution of the Middle Yangtze River

Plate subduction leads to complex exhumation processes on continents.The Huangling Massif lies at the northern margin of the South China Block.Whether the Huangling Massif was exhumed as a watershed of the middle reaches of the Paleo-Yangtze River during the Mesozoic remains under debate.We examined the exhumation history of the Huangling Massif based on six granite bedrock samples,using apatite fission track(AFT)and apatite and zircon(U-Th)/He(AHe and ZHe)thermochronology.These samples yielded ages of 157–132 Ma(ZHe),119–106 Ma(AFT),and 114–72 Ma(AHe),respectively.Thermal modeling revealed that three phases of rapid cooling occurred during the Late Jurassic–Early Cretaceous,late Early Cretaceous,and Late Cretaceous.These exhumation processes led to the high topographic relief responsible for the emergence of the Huangling Massif.The integrated of our new data with published sedimentological records suggests that the Huangling Massif might have been the watershed of the middle reaches of the Paleo-Yangtze River since the Cretaceous.At that time,the rivers flowed westward into the Sichuan Basin and eastward into the Jianghan Basin.The subduction of the Pacific Plate beneath the Asian continent in the Mesozoic deeply influenced the geomorphic evolution of the South China Block.

Biogeochemistry of sedimentary organic matter in the Yongjiang River estuary in the southern part of Hangzhou Bay,China,since the Late Pleistocene

A sediment core(YJK19-02)collected from the southern outlet of Hangzhou Bay near the Yongjiang River estuary in East China was analyzed for grain size,lignin,bulk elemental composition,stable carbon isotope,and rare earth elements(REEs)to determine the sources and diagenesis of sedimentary organic matter(OM)of the estuary and adjacent areas since the Late Pleistocene.δ^(13)C values(-24.80‰–-23.60‰),total organic carbon/total nitrogen(TOC/TN)molar ratios(8.00–12.14),and light rare earth element/heavy rare earth element ratios(LREE/HREE=8.34–8.91)revealed the predominance of terrestrial sources of OM,mainly from the Changjiang(Yangtze)River.The lignin parameters of syringyl/vanillyl(S/V=0.20–0.73)and cinnamyl/vanillyl(C/V=0.03–0.19)ratios indicate the predominance of nonwoody angiosperms,and the vanillic acid/vanillin ratios[(Ad/Al)_(V)=0.32–1.57]indicate medium to high degrees of lignin degradation.An increasing trend ofΛ(total lignin in mg/100-mg OC)values from ca.14500 a BP to ca.11000 a BP reflected the increase in temperature during the Late Pleistocene.However,a time lag effect of temperature on vegetation abundance was also revealed.The relatively higher and stableΛvalues correspond to the higher temperature during the mid-Holocene from ca.8500 a BP to ca.4500 a BP.Λvalues decreased from ca.4000 a BP to the present,corresponding to historical temperature fluctuations during this time.Our results show that the vegetation abundance in the Yongjiang River Basin since the Late Pleistocene was related to the temperature fluctuation duo to climate change.

Tetrabromobisphenol A and hexabromocyclododecane in sediments from the Zhujiang(Pearl) River Estuary and South China Sea

Marine sediments collected from the Zhujiang(Pearl) River Estuary(ZRE) and South China Sea(SCS) were utilized to study the occurrence and spatial distribution of tetrabromobisphenol A(TBBPA) and hexabromocyclododecane(HBCDD).The levels of TBBPA and HBCDD in sediments ranged from not detected(nd) to 6.14 ng/g dry weight(dw) and nd to 0.42 ng/g dw.TBBPA concentrations in marine sediments were substantially higher than HBCDD.The concentrations of TBBPA and HBCDD in the ZRE sediments were significantly greater than those in the SCS.α-HBCDD(48.7%) and γ-HBCDD(46.2%) were the two main diastereoisomers of HBCDD in sediments from the ZRE,with minor contribution of β-HBCDD(5.1%).HBCDD were only found in one sample from the northern SCS.The enantiomeric fraction of α-HBCDD in sediments from the ZRE was obviously greater than 0.5,indicating an accumulation of(+)-α-HBCDD.The enantiomers of HBCDD were not measured in sediments from the SCS.This work highlighted the environmental behaviors of TBBPA and HBCDD in marine sediments.

Effects of phosphorus limitation on sinking velocities of phytoplankton during summer in the Changjiang River Estuary

The sinking of phytoplankton is critical to organic matter transportation in the ocean and it is an essential process for the formation of coastal hypoxic zones.This study was based on a field investigation conducted during the summer of 2022 in the Changjiang River(Yangtze River) Estuary(CJE) and its adjacent waters.The settling column method was employed to measure the sinking velocity(SV) of different size fractions of phytoplankton at the surface of the sea and to analyze their environmental control mechanisms.The findings reveal significant spatial variation in phytoplankton SV(-0.55-2.41 m/d) within the CJE.High-speed sinking was predominantly observed in phosphate-depleted regions beyond the CJE front.At the same time,an upward trend was more commonly observed in the phosphate-rich regions near the CJE mouth.The SV ranges for different sizefractionated phytoplankton,including micro-(>20 μm),nano-(2-20 μm),and picophytoplankton(0.7-2 μm),were-0.50-4.74 m/d,-1.04-1.59 m/d,and-1.24-1.65 m/d,respectively.Correlation analysis revealed a significant negative correlation between SV and dissolved inorganic phosphorus(DIP),implying that the influence of DIP contributes to SV.The variations in phytoplankton alkaline phosphatase activity suggested a significant increase in SV across all size fractions in the event of phosphorus limitation.Phytoplankton communities with limited photo synthetic capacity(maximum photochemical efficience,Fv/Fm <0.3) were found to have higher SV than that of communities with strong capacity,suggesting a link between sinking and alterations in physiological conditions due to phosphate depletion.The findings from the in situ phosphate enrichment experiments confirmed a marked decrease in SV following phosphate supplementation.These findings suggest that phosphorus limitation is the primary driver of elevated SV in the CJE.This study enhances the comprehension of the potential mechanisms underlying hypoxic zone formation in the CJE,providing novel insights into how nearshore eutrophication influences organic carbon migration.

The 2022 Extreme Heatwave in Shanghai,Lower Reaches of the Yangtze River Valley:Combined Influences of Multiscale Variabilities

In the summer of 2022,China(especially the Yangtze River Valley,YRV)suffered its strongest heatwave(HW)event since 1961.In this study,we examined the influences of multiscale variabilities on the 2022 extreme HW in the lower reaches of the YRV,focusing on the city of Shanghai.We found that about 1/3 of the 2022 HW days in Shanghai can be attributed to the long-term warming trend of global warming.During mid-summer of 2022,an enhanced western Pacific subtropical high(WPSH)and anomalous double blockings over the Ural Mountains and Sea of Okhotsk,respectively,were associated with the persistently anomalous high pressure over the YRV,leading to the extreme HW.The Pacific Decadal Oscillation played a major role in the anomalous blocking pattern associated with the HW at the decadal time scale.Also,the positive phase of the Atlantic Multidecadal Oscillation may have contributed to regulating the formation of the double-blocking pattern.Anomalous warming of both the warm pool of the western Pacific and tropical North Atlantic at the interannual time scale may also have favored the persistency of the double blocking and the anomalously strong WPSH.At the subseasonal time scale,the anomalously frequent phases 2-5 of the canonical northward propagating variability of boreal summer intraseasonal oscillation associated with the anomalous propagation of a weak Madden-Julian Oscillation suppressed the convection over the YRV and also contributed to the HW.Therefore,the 2022 extreme HW originated from multiscale forcing including both the climate warming trend and air-sea interaction at multiple time scales.

Coastal hypoxia response to the coupling of catastrophic flood,extreme marine heatwave and typhoon:a case study off the Changjiang River Estuary in summer 2020

Massive bodies of low-oxygen bottom waters are found in coastal areas worldwide,which are detrimental to coastal ecosystems.In summer 2020,the response of coastal hypoxia to extreme weather events,including a catastrophic flooding,an extreme marine heatwave,and Typhoon Bavi,is investigated based on multiple satellite,four cruises,and mooring observations.The extensive fan-shaped hypoxia zone presents significant northward extension during July-September 2020,and is estimated as large as 13 000 km^(2) with rather low oxygen minimum(0.42 mg/L) during its peak in 28-30 August.This severe hypoxia is attributed to the persistent strong stratification,which is indicated by flood-induced larger amount of riverine freshwater input and subsequent marine heatwave off the Changjiang River Estuary.Moreover,the Typhoon Bavi has limited effect on the marine heatwave and coastal hypoxia in summer 2020.

City Network Evolution Characteristics of Smart Industry: Evidence from Yangtze River Delta, China

The dual-path model of industrial evolution and spatial progression has been widely acknowledged and incorporated into the strategic planning to promote the development of urban industries and regional collaborations.However,current research on inter-enter-prise city networks mainly focuses on the single sector of flows on all enterprise branches,such as product value chains and production factors,but neglects that of particular industry department.Built upon the new economic geography and city networks theory,this paper develops a methodological framework that focuses on the analysis of city network evolution characteristics of smart industry.Particu-larly,a conceptual model of smart industry enterprise-industry-city is proposed and then applied to a case study of smart industry in the Yangtze River Delta Region,China.Using enterprise supplier-customer data,a city network of smart industry is constructed and sub-sequently analyzed with the proposed model.Findings indicate that the smart industry network in Yangtze River Delta Region exhibits a hierarchical structure and the expansion of the network presents a small-world network characteristic.The study not only makes a meth-odological contribution for revealing the industrial and spatial evolution path of the current smart industry,but also provides empirical support for the formulation of new economic development policies focused on smart industries,demonstrating the role of city clusters as carriers of regional synergistic development.

Structural Characteristics and Influencing Factors of Carbon Emission Spatial Association Network:A Case Study of Yangtze River Delta City Cluster,China

City cluster is an effective platform for encouraging regionally coordinated development.Coordinated reduction of carbon emissions within city cluster via the spatial association network between cities can help coordinate the regional carbon emission management,realize sustainable development,and assist China in achieving the carbon peaking and carbon neutrality goals.This paper applies the improved gravity model and social network analysis(SNA)to the study of spatial correlation of carbon emissions in city clusters and analyzes the structural characteristics of the spatial correlation network of carbon emissions in the Yangtze River Delta(YRD)city cluster in China and its influencing factors.The results demonstrate that:1)the spatial association of carbon emissions in the YRD city cluster exhibits a typical and complex multi-threaded network structure.The network association number and density show an upward trend,indicating closer spatial association between cities,but their values remain generally low.Meanwhile,the network hierarchy and network efficiency show a downward trend but remain high.2)The spatial association network of carbon emissions in the YRD city cluster shows an obvious‘core-edge’distribution pattern.The network is centered around Shanghai,Suzhou and Wuxi,all of which play the role of‘bridges’,while cities such as Zhoushan,Ma'anshan,Tongling and other cities characterized by the remote location,single transportation mode or lower economic level are positioned at the edge of the network.3)Geographic proximity,varying levels of economic development,different industrial structures,degrees of urbanization,levels of technological innovation,energy intensities and environmental regulation are important influencing factors on the spatial association of within the YRD city cluster.Finally,policy implications are provided from four aspects:government macro-control and market mechanism guidance,structural characteristics of the‘core-edge’network,reconfiguration and optimization of the spatial layout of the YRD city cluster,and the application of advanced technologies.

Regional Brand and High-quality Development of Fruits in Ethnic Areas of the Yangtze River Economic Belt under the Greater Food Approach

Establishing the Greater Food Approach and promoting the Yangtze River Economic Belt s national major regional development strategy can better support and serve the agricultural power and Chinese-style modernization.This paper introduces the characteristics of fruit industry in 16 autonomous prefectures and 47 autonomous counties under the jurisdiction of the Yangtze River Economic Belt.It studies the intellectual property resources of brand marks from the aspects of geographical indications,collective trademarks,certification trademarks,well-known trademarks in China and national design patents,and analyzes the main problems of brand and high-quality development of fruit industry in these ethnic autonomous areas.Finally,it puts forward some strategies,such as improving the protection of intellectual property rights of geographical indications,using intellectual property rights of brand signs,building modern seed industry upgrading project,drawing lessons from the experience of thousand villages demonstration project,ensuring that large-scale poverty does not occur,and building a diversified food supply system.

Spatial-temporal Divergence Characteristics and Driving Factors of Green Economic Efficiency in the Yangtze River Economic Belt of China

The spatial and temporal variation of green economic efficiency and its driving factors are of great significance for the con-struction of high-efficiency and low-consumption green development model and sustainable socio-economic development.The research focused on the Yangtze River Economic Belt(YREB)and employed the miniumum distance to strong efficient frontier DEA(MinDs)model to measure the green economic efficiency of the municipalities in the region between 2008 and 2020.Then,the spatial autocorrel-ation model was used to analyze the evolution characteristics of its spatial pattern.Finally,Geodetector was applied to reveal the drivers and their interactions on green economic efficiency.It is found that:1)the overall green economic efficiency of the YREB from 2008 to 2020 shows a W-shaped fluctuating upward trend,green economic efficiency is greater in the downstream and smallest in the upstream;2)the spatial distribution of green economic efficiency shows clustering characteristics,with multi-core clustering based on‘city clusters-central cities'becoming more obvious over time;the High-High agglomeration type is mainly clustered in Jiangsu and Zheji-ang,while the Low-Low agglomeration type is clustered in the western Sichuan Plateau area and southwestern Yunnan;3)from input-output factors,whether it is the YREB as a whole or the upper,middle and lower reaches regions,the economic development level,labor input,and capital investment are the leading factors in the spatial-temporal evolution of green economic efficiency,with the com-prehensive influence of economic development level and pollution index being the most important interactive driving factor;4)from so-cio-economic factors,information technology drivers such as government intervention,transportation accessibility,information infra-structure,and Internet penetration are always high impact influencers and dominant interaction factors for green economic efficiency in the YREB and the three major regions in the upper,middle and lower reaches.Accordingly,the article puts forward relevant policy re-commendations in terms of formulating differentiated green transformation strategies,strengthening network leadership and informa-tion technology construction and coordinating multi-factor integrated development,which could provide useful reference for promoting synergistic green economic efficiency in the YREB.

Analysis of factors influencing carbon emissions in the Yangtze River Delta region and projections of carbon peak scenarios

Based on the supply-side perspective,the improved STIRPAT model is applied to reveal the mechanisms of supply-side factors such as human,capital,technology,industrial synergy,institutions and economic growth on carbon emissions in the Yangtze River Delta(YRD)through path analysis,and to forecast carbon emissions in the YRD from the baseline scenario,factor regulation scenario and integrated scenario to reach the peak.The results show that:(1)Jiangsu's high carbon emission pattern is the main reason for the YRD hindering the synergistic regulation of carbon emissions.(2)Human factors,institutional factors and economic growth factors can all contribute to carbon emissions in the YRD region,while technological and industrial factors can generally suppress carbon emissions in the YRD region.(3)Under the capital regulation scenario,the YRD region has the highest level of carbon emission synergy,with Jiangsu reaching its peak five years earlier.Under the balanced regulation scenario,the YRD region as a whole,Jiangsu,Zhejiang and Anhui reach the peak as scheduled.

Land Use Dynamics and Ecosystem Service Value Changes in the Yangtze River Delta Urban Agglomeration Under Different Scenarios

Urban agglomerations,serving as pivotal centers of human activity,undergo swift alterations in ecosystem services prompted by shifts in land utilization.Strengthening the monitoring of ecosystem services in present and future urban agglomerations contributes to the rational planning of these areas and enhances the well-being of their inhabitants.Here,we analyzed land use conversion in the Yangtze River Delta(YRD)urban agglomeration during 1990-2020 and discussed the spatiotemporal response and main drivers of changes in ecosystem service value(ESV).By considering the different development strategic directions described in land use planning policies,we predicted land use conversion and its impact on ESV using the Future Land Use Simulation(FLUS)model in three scenari-os in 2025 and 2030.Results show that:1)from 1990 to 2020,land use change is mainly manifested as the continuous expansion of con-struction land to cultivated land.Among the reduced cultivated land,82.2%were occupied by construction land.2)The land use types conversion caused a loss of 21.85 billion yuan(RMB)in ESV during 1990-2020.Moreover,the large reduction of cultivated land area led to the continuous decline of food production value,accounting for 13%of the total ESV loss.3)From 2020 to 2030,land use change will mainly focus on Yangzhou and Zhenjiang in central Jiangsu Province and Taizhou in southern Zhejiang Province.Under the BAU(natural development)and ED(cultivated land protection)scenarios,construction land expansion remains dominant.In contrast,under the EP(ecological protection)scenario,the areas of water bodies and forest land increase significantly.Among the different scenarios,ESV is highest in the EP scenario,making it the optimal solution for sustainable land use.It can be seen that the space use conflict among urban,agriculture and ecology is a key factor leading to ESV change in the urban agglomeration of Yangtze River Delta.There-fore,it is crucial to maintain spatial land use coordination.Our findings provide suggestions for scientific and rational land use planning for the urban agglomeration.

Promoting High-quality Development of Grain and Oil in Ethnic Areas of the Yangtze River Economic Belt from the Perspective of Agricultural Power

Accelerating the construction of agricultural power,further promoting the high-quality development of the Yangtze River Economic Belt,and better supporting and serving Chinese-style modernization are the key issues at present.This paper first introduces the Yangtze River Economic Belt and its ethnic areas,and studies the characteristics of the grain and oil industry in the ethnic autonomous areas of the economic belt,as well as the current situation of various types of intellectual property resources,such as industrial cultural heritage,scientific and tech-nological innovation,and brand marking intellectual property.Besides,it analyzes the main problems in the high-quality development of grain and oil in the Yangtze River Economic Belt ethnic areas.Finally,it comes up with recommendations,including protecting the intellectual prop-erty rights of cultural heritage in the field of grain and oil,leading the inheritance and development of excellent traditional Chinese culture,use scientific and technological innovation intellectual property rights to promote the innovation-driven development strategy of the grain and oil in-dustry,and providing counterpart assistance to ethnic autonomous areas in the Yangtze River Economic Belt to further promote the high-quality development of the Yangtze River Economic Belt.

Evaluation of Ecological Sustainable Development in the Yangtze River Delta Region Based on Ecological Footprint Theory

The ecological footprint was employed as a quantitative indicator of resource inputs,enabling a detailed account of the structure of biological resources and energy occupancy,as well as the variation of resource productivity in the Yangtze River Delta(YRD)Region.From 2004 to 2018,there were notable variations in the ecological productivity of different types of land on basis of China’s equilibrium factor across the three provinces and one city in the YRD region.Jiangsu Province exhibited the highest ecological productivity of arable land,while Anhui Province exhibited the highest ecological productivity of forest land.Shanghai City exhibited the highest ecological productivity of pasture land,while Zhejiang Province exhibited the highest ecological productivity of water area.In 2018,the proportion of arable land within the total ecological carrying capacity of the YRD region reached 74.35%.Furthermore,the contribution of Jiangsu and Anhui provinces to the YRD’s total ecological carrying capacity was 41.36%and 41.26%,respectively.In the construction of a new development pattern in the YRD region,which is dominated by the domestic cycle as the main body and mutually reinforced by domestic and international double-cycle,the YRD region should combine the utilization of natural forces with innovation in science,technology and cooperation mechanisms.Furthermore,the government should guide the concentration of social capital towards green industries.It is also recommended that the moderate reduction of ecological footprints should be encouraged,and that the security of biological resources and energy,the leadership in the field of cutting-edge science and technology should be ensured in YRD region.This will facilitate the formation of a new development pattern of higher-quality integration at the national level firstly.

Interdecadal change and projection of the relationship between spring Arctic Oscillation and summer precipitation in the Yangtze River valley in CMIP6 models

评估了20个CMIP6模式对春季北极涛动(AO)与长江流域夏季降水(YRP)关系的模拟能力.结果表明, 4个模式(ACCESS-ESM1-5, CMC-CM2-SR5, MRI-ESM2-0, NorESM2-LM))能合理模拟出1990年代后期AO-YRP关系的减弱. 1980-1998年,当春季AO位于正位相时,夏季东亚急流北移,长江流域为异常下沉运动,同时西太平洋副热带高压减弱,减少向长江流域的水汽输送,结果导致降水减少. 1999-2014年,上述大气环流与春季AO的联系不显著,从而减弱AO-YRP的关系.利用这四个模式进一步预估了RCP4.5情景下2015-2100年期间AO-YRP的关系.两者在2015-2040年为显著负相关关系,随后再次减弱.

Distribution and Controlling Factors of Dissolved Gaseous Mercury and Reactive Mercury in Seawater Near Yangtze River Estuary

Complex hydrocultural conditions in the estuary affect the migration and transformation of mercury.Using two voyages in July and October 2018,Dissolved Gaseous Mercury(DGM)and Reactive Mercury(RHg)were determined to explore the source,transformation and influence of DGM content in the adjacent waters of Yangtze River Estuary in summer and autumn.The results showed the contents of DGM and RHg in summer were higher than those in autumn,and both of them were higher than those in open sea.In summer and autumn,the Yangtze River brought a higher concentration of DGM,and different flow direction and runoff resulted in differences in the high value region of the surface.The emergence of low-oxygen zones in summer was conducive to the production of DGM.In autumn,windy weather allowed seawater disturbances to promote the release of mercury from the underlying sediments,especially in shallow sea in northwest.RHg showed a higher concentration in the offshore than in the open sea in summer,but there was no such trend in autumn,reflecting the influence of less runoff input.DGM is the main product of RHg reduction,and there was a significant positive correlation between DGM and RHg in summer(r=0.356,P<0.05),while the correlation between DGM and RHg was not significant in autumn due to the influence of light intensity,wind speed and nutrients.The exchange flux of mercury in the adjacent waters of the Yangtze River Estuary was higher than that in the open sea.There was no significant difference of the release flux of mercury in summer and autumn.This article highlighted that the input of mercury from the Yangtze River runoff promotes the release of mercury in seawater,and the hypoxic zone caused by eutrophication is conducive to the production of DGM.

Study on Volume Variation and Stability of Riverbed in the Yangtze Estuary

In recent years,regional floods and typhoons have occurred in the Yangtze Estuary.Changing dynamic conditions and dramatic reduction of sediment discharge in the basin are affecting the dynamic equilibrium pattern of the Yangtze Estuary.Based on the field measurement data and theoretical derivation,this paper analyzed the changing process of runoff-sediment discharge into the sea after the operation of the Three Gorges Project(TGP),and the tidal dynamics and sediment variation characteristics of the Yangtze Estuary.The erosion of South Branch mainly occurs in the channel below-10 m contour,and the riverbed volume below contours 0 m and-10 m has a good correlation with the sediment discharge of Datong Station in the previous year.On this basis,the ratio of the horizontal distance from the starting point to the section centroid below the average water level(B_c)and the water depth at the section centroid(H_c)was proposed to describe the change of the section shape.The relationships between the water-diverting ratio,the sediment-diverting ratio and the water-diverting angle,the conditions of runoff and sediment discharge from the upper reach and the characteristics of the riverway section were established,and the theoretical calculation equations of the water-diverting ratio,the sediment-diverting ratio and the diverting angle of each bifurcation were also established.

Yangtze River Estuary No.2 Ancient Vessel:An Important Discovery of Underwater Archaeology in China

Under the warm sun at noon in early winter,the special salvage ship loaded with Yangtze River Estuary No.2 Ancient Vessel slowly entered the No.1 dock of the former site of Shanghai Shipyard.The curved beam caisson was seated,marking the successtul completion of the overall salvage of the ancient vessel.Then came a new stage of archaeological excavation,overall protection of cultural heritage and museum construction planning.