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Applications of EMD to analyses of high-frequency beachface responses to Storm Bebinca in the Qing’an Bay,Guangdong Province,China

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Acta Oceanologica Sinica 2022年第5期41卷 147-162页

作者： Taihuan Hu Zhiqiang li Chunhua Zeng gaocong li Huiling Zhang College of Electronic and Information Engineering Guangdong Ocean UniversityZhanjiang524088China South China Sea Resources Big Data Center Southern Marine Science and Engineering Guangdong Laboratory(Zhanjiang)Zhanjiang524000China College of Ocean Engineering Guangdong Ocean UniversityZhanjiang524088China

On average,five to six storms occur in the Qiongzhou Strait every year,causing significant damage to coastal geomorphology and several property losses.Tropical Storm Bebinca is the most unusual and complex storm event that has occurred in this region over the last 10 years.To detect the high-frequency beachface responses to the storm,a pressure sensor was deployed in the surf zone to record the free sea surface height,and the heights of grid pile points on the beachface were measured manually to determine beach elevation changes during this storm.Empirical Mode Decomposition and related analysis techniques were used to analyze the high-frequency topography and wave data.The results showed that:(1)the beachface response process occurred in three stages.The first stage was the rapid response stage,wherein the spring tide berm began to erode significantly,and the front edge of the beach berm reacted closely.The two beach sections resisted the harmful energy of the main storm.In the second stage,the beach slope increased after a large sediment loss on the beach berm and its front edge.To adapt to the storm energy,the beach at the low tide line began to erode,and the beach slope decreased.In the third stage,after the storm turned,the wave energy was significantly attenuated,and the beach berm eroded to resist the residual wave energy.The beachface began to oscillate and recover.(2)The main wave surface was the superimposed product of a few internal mode functions.Similar results were observed in beachface changes.High-frequency driving factors determine the local characteristics of beach evolution,and low-frequency driving factors determine the beach evolution trend.(3)The response of sediment to the storm was not a single sea-transportation,but a single-or two-way conversion driven by factors such as wave energy,swash flow,and secondary wave breaking.(4)TheΩ-RTR model is not completely applicable to beach states that undergo rapid changes during storms.Therefore,it is necessary to carry out further research on beach

关键词： EMD internal mode functions Bebinca beach response wave energy beach state

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Coastal erosion risk assessment of Hainan Island, China

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Acta Oceanologica Sinica 2023年第7期42卷 79-90页

作者： Qianxin Su Zhiqiang li gaocong li Daoheng Zhu Pengpeng Hu College of Electronics and Information Engineering Guangdong Ocean UniversityZhanjiang 524088China

Coastal erosion on islands is increasing due to sea level rise,frequent extreme events,and anthropogenic activities.However,studies on the multifactorial coastal erosion risk and the vulnerability of islands are limited.In this study,the Coastal Erosion Risk Assessment(CERA)method was applied for the first time to the study area in China to assess the erosion risk on the coast of Hainan Island;to explore the effects of coastal ocean dynamics,sediment movement characteristics,and anthropogenic construction;and to discuss the suitability of the method and countermeasures for coastal protection.The results show that the coast of Hainan Island shows high sensitivity,high value,low exposure,and moderate erosion.The whole island showed high vulnerability but low erosion risk,with the eastern region being more affected by erosion,particularly the eastern side of Wulong Port and Yalin Bay in Wenchang,and the shore section of Yalong Bay in Sanya,having a very high risk of coastal erosion.In addition,Monte Carlo simulation was used to check the applicability of the CERA method,and it was found that the rate of shoreline change,population density,and number of storms significantly contributed to coastal erosion,but only the short-term effects of sea level rise were considered.The effects of sea level rise and sediment grain size were primarily analyzed as influencing factors.The effects of sea level rise continue to strengthen,with coastal retreat expected to be greater than 2 m by the mid-21st century.Moreover,Hainan Island is primarily composed of the fine and medium sand types,which have little resistance to coastal erosion.Currently,the impact of sediment grain size is rarely considered in coastal erosion risk assessment studies.However,it can be incorporated into the indicator system in the future,and the spatial variation of indicators can be fully considered to strengthen the refinement study.

关键词： coastal erosion Coastal Erosion Risk Assessment(CERA) vulnerability risk influence factor

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Comparison of the graphic and moment methods for analyzing grainsize distributions: A case study for the Chinese inner continental shelf seas

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International Journal of Sediment Research 2022年第6期37卷 729-736页

作者： gaocong li Rihong Du Jieping Tang Zhiqiang li Qiong Xia Benwei Shi liang Zhou Yang Yang Wenxiang Zhang Department of Marine Technology Guangdong Ocean University Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) State Key Laboratory for Estuarine and Coastal Research East China Normal University School of Geography Geomatics and Planning Jiangsu Normal University School of Marine Science and Engineering Nanjing Normal University

Sediment grain-size distributions provide key information on sediment sources, transport, and deposition. The Folk and Ward graphic method and the Friedman moment method are generally used for rapid analysis of the qualitative and quantitative properties of sediment samples; whether the two methods yield the same results for any given sediment sample is not yet known. little research attention has been paid to comparison of the descriptive terms used in both methods, although some work has been done on comparison of the numerical values. In the current study, sediment samples from six areas of the Chinese inner continental seas were investigated. The mean and sorting values obtained using the two methods are well correlated(0.821 ≤ R~2≤ 0.998), but the skewness and kurtosis vary among study areas(0.035 ≤ R~2≤ 0.816), which is consistent with previous studies where R~2 is the coefficient of determination. The two methods yield significant differences for skewness(84.78%-98.04% of samples) and kurtosis(40.59%-67.29% of samples). The main reasons for these differences are variations in the grainsize distribution curves of the sediment samples and differences in the weighting applied to specified cumulative percentile values by the two methods. These results demonstrate that the differences between the two methods should be taken into account when analyzing sedimentary environments and studying historical data.

关键词： Grain-size parameters Graphic method for grain size distribution Moment method for grain size distribution Grain-size descriptive terms China seas

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Geometric modeling of Holocene large-river delta growth patterns,as constrained by environmental settings

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Science China Earth Sciences 2021年第2期64卷 318-328页

作者： gaocong li Qiong XIA Yaping WANG Zhiqiang li Shu GAO Department of Marine Technology Guangdong Ocean UniversityZhanjiang 524088China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519000China Marine Resources Big Data Center of South China Sea Southern Marine Science and Engineering Guangdong Laboratory(Zhanjiang)(Zhanjiang Bay Laboratory)Zhanjiang 524088China State Key Laboratory for Estuarine and Coastal Research East China Normal UniversityShanghai 200046China

Topographic/bathymetric conditions of the continental shelf can significantly influence the long-term growth of river deltas.In particular,these conditions constrain the accommodation space for sedimentation in the deltaic areas.In this study,we use a conceptual geometric model to evaluate the role played by this factor,on the basis of the principle of mass conservation.The Ganges-Brahmaputra,Mekong and Nile deltas are examined as three typical examples,in terms of their different original seabed morphologies.The control variate method is applied to eliminate the effect of the difference in model input variables.The results show that,assuming a constant sediment load,the delta growth rate will decrease with time;a higher value of the original seabed slope leads to a lower shoreline progradation rate for the subaerial delta and a higher growth rate for the subaqueous delta.Thus,the original seabed morphology represented by slope is a critical factor affecting the evolution of Holocene large-river deltas.These results explain the interrelationships between sediment load,deltaic plain area,and the original seabed slopes for the 27 large-river deltas worldwide,located in the middle/low latitudes,with different tectonic backgrounds.In the future,the conceptual geometric model may be combined with sediment dynamic modeling to identify more details of the evolution of these deltas.

关键词： Large-river deltas Original topography/bathymetry Geometric modeling Growth geometry Holocene

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Calculating the sediment flux of the small coastal watersheds:a modification of global equations

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Acta Oceanologica Sinica 2021年第1期40卷 147-154页

作者： gaocong li Qiong Xia Dongyang Fu Chunhua Zeng Zhiqiang li Shu Gao Department of Marine Technology Guangdong Ocean UniversityZhanjiang 524088China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519000China College of Ocean Engineering Guangdong Ocean UniversityZhanjiang 524088China State Key Laboratory for Estuarine and Coastal Research East China Normal UniversityShanghai 200046China

Two kinds of regression equations are used to reproduce the sediment flux of the 26 small coastal watersheds in southeastern China.The first kind is the global equations suggested by Milliman and Syvitski(1992),Mulder and Syvitski(1996),Syvitski et al.(2003),and Syvitski and Milliman(2007).The second kind is the modified equations revised by the characteristics of the coastal watersheds,including the drainage area,mean water discharge,and mean sediment discharge.Compared with the observations of the hydrometric stations,the global equations overestimate the sediment flux by 1–2 orders of magnitude.By using the modified equations,the accuracy of the estimated sediment flux is significantly improved,with the relative error in the range of 7%–24%.The reason for the overestimation mainly caused by different parameters’domain and regression coefficients between global rivers and study coastal watersheds.This study demonstrates that modification needs to be considered when using global regression equations to reproduce the sediment flux of the small coastal watersheds in southeastern China.

关键词： sediment flux global equation modified equation small coastal watersheds southeast China

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Predicting sediment flux from continental shelf islands,southeastern China

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Journal of Oceanology and limnology 2021年第2期39卷 472-482页

作者： gaocong li Xiaoming XIA Jianjun JIA Yaping WANG Tinglu CAI Shu GAO Department of Marine Technology Guangdong Ocean UniversityZhanjiang 524088China Second Institute of Oceanography Ministry of Natural ResourcesHangzhou 310012China State Key Laboratory for Estuarine and Coastal Research East China Normal UniversityShanghai 200241China

Continental shelf islands are contributors of terrestrial sediment supply to shelf regions,and the sediment flux from these islands shall be quantified.We calculated the sediment flux of continental shelf islands in the southeastern China using two empirical equations under two preconditions.The first,the sediment load/yield of the islands has the same pattern as the adjacent small,mountainous rivers along the coastline;and the second,each of the islands was treated as a single catchment.The results show that the sediment supply from these islands reached an order of magnitude of 1 Mt/a,which is comparable to the supply from the local smaller rivers.A sensitivity analysis indicates that this value represents the lower limit of estimate;if the accurate amount of sub-catchments of any island is considered,then this value will be enhanced slightly.This study demonstrates that the sediment supply from continental shelf islands to oceans is an important factor affecting the regional sedimentation and,therefore,should be paid with attention.

关键词： continental shelf islands sediment flux local rivers shelf mud deposits East and South China Seas

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Tracking historical storm records from high-barrier lagoon deposits on the southeastern coast of Hainan Island,China

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Acta Oceanologica Sinica 2021年第11期40卷 162-175页

作者： liang Zhou Xiaomei Xu Yaping Wang Jianjun Jia Yang Yang gaocong li Changliang Tong Shu Gao School of Geography Geomaticsand PlanningJiangsu Normal UniversityXuzhou 221116China Hainan Key Laboratory of Marine Geological Resources and Environment Haikou 570206China State Key Laboratory of Estuarine and Coastal Research East China Normal UniversityShanghai 200046China Ministry of Education Key Laboratory for Coast and Island Development Nanjing UniversityNanjing 210023China School of Marine Science and Engineering Nanjing Normal UniversityNanjing 210046China Department of Marine Technology Guangdong Ocean UniversityZhanjiang 524088China

The relationship between storm activity and global warming remains uncertain.To better understand storm–climate relationships,coastal lagoon deposits are increasingly being investigated because they could provide high-resolution storm records long enough to cover past climate changes.However,site-specific sediment dynamics and high barriers may bias storm reconstructions.Here,we aimed to investigate these factors through the reconstruction of five distinct storm records(XCL-01,XC-03,XC-06,XC-07,XC-08)from different water depths in a lagoon with a high barrier(i.e.,Xincun Lagoon of Hainan Island).Sediment cores were characterized using high-resolution grain size and XRF measurements,to identify storm events.These data were coupled with a numerical simulation to obtain bed shear stress data with high-spatial resolution to better understand storm-induced sediment transport mechanisms.^(210) Pb dating and Pb pollution chronostratigraphic markers indicated that the chronology of the storm deposit sequences of the cores span the period between 117 a and 348 a.The grain size and XRF results indicated numerous,highly variable and short-duration fluctuations,suggesting that storm-induced coarse-grained sediments were deposited at these core sites.The inconsistent storm events recorded in these cores suggest that these sites have different preservation potentials for storm deposits.However,the consistence between storm sediment records and historical documents for Core XCL-01 indicates that high-barrier lagoons could provide long-term storm event records with high preservation potential.

关键词： storm deposits preservation potential sediment dynamics high-barrier lagoon Hainan Island

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基于文献计量分析的根系分泌物研究进展

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中国农学通报 2024年第7期40卷 144-154页

作者：王雨菡陈莲张培珍李高聪王振江唐翠明林森罗国庆钟建武李智毅王圆广东省农业科学院蚕业与农产品加工研究所广州510610 广东海洋大学电子与信息工程学院广东湛江524088 农业农村部华南都市农业重点实验室广州510610

为深入了解根系分泌物研究进展及发展趋势,以Web of Science核心合集数据库2002-2022年根系分泌物的相关文献为数据源,采用文献计量学方法,借助软件VOSviewer和CiteSpace对年发文量、高产发文国家间合作关系、发文机构、期刊分布、文献... 详细信息

为深入了解根系分泌物研究进展及发展趋势,以Web of Science核心合集数据库2002-2022年根系分泌物的相关文献为数据源,采用文献计量学方法,借助软件VOSviewer和CiteSpace对年发文量、高产发文国家间合作关系、发文机构、期刊分布、文献共被引和高频关键词等进行可视化处理,并对不同研究阶段主要研究内容进行分析。结果表明,近20年根系分泌物研究领域年发文量总体呈上升趋势,在国际范围内受重视程度越来越高。中国、美国合作关系密切且合作发文最多,中国科学院与美国科罗拉州立大学致力于该领域研究并做出突出贡献,《Plant and Soil》和《Soil Biology&Biochemistry》为主要载体。生态系统、根际微生物、有机酸、基因、胁迫和植物适应性为根系分泌物研究的核心主题;不同研究阶段主要研究内容由早及近表现为信号传导—养分获取—化感作用—植物修复—植物与微生物互作。在分子水平上揭示植物与根际微生物的互作机理、根系分泌物与根际微生物在植物生长过程中的调控功能及分子机制等更为细化的研究将会成为未来一段时间的新兴研究热点。

关键词：根系分泌物可视化分析文献计量 VOSviewer CiteSpace

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Typhoon events recorded in coastal lagoon deposits,southeastern Hainan Island

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Acta Oceanologica Sinica 2017年第4期36卷 37-45页

作者： ZHOU liang GAO Shu YANG Yang ZHAO Yangyang HAN Zhuochen li gaocong JIA Peihong YIN Yong ing 210093 China Ministry of Education Key Laboratory for Coast and Island Development Nanjing University Nanjing 210093 China

Coastal lagoon deposits provide evidence for the magnitude and frequency of past tropical cyclones prior to instrumental records and historical documentation.In the present study,we attempt to analyze the sedimentary records containing typhoon information for the northern South China Sea region.For this purpose,sediment cores were collected from two coastal lagoons in the southeastern Hainan Island,and were analyzed in laboratory to derive the data sets about grain size,organic and inorganic carbon contents,and deposition rates.The grain size and organic-inorganic carbon data were used to formulate the proxies of typhoon events.The deposition rates,as calculated using the CRS 210 Pb method,are around 0.5 mm/a for both lagoons,on the basis of which an age model is established.Within the cores,sedimentary layers associated with 35 typhoon events have been identified.On such a basis,a 350 year history of local typhoon activities is reconstructed by incorporating the 210 Pb dating results,typhoon-induced sedimentation patterns and the historical documents.A comparison of the frequency of typhoon occurrence with the regional climate records indicates that the observed changes in tropical cyclone activity patterns,as revealed by the lagoon sedimentary records,may be related to El Ni？o,Pacific Decadal Oscillation（PDO）,North Atlantic Oscillation（NAO）,sunspot,and other potential climate drivers that affect the tropical cyclone variability.This study demonstrates that the sedimentary record of storms can be analyzed in combination with historical documents,to provide meaningful information on past storm activities and their long-term variability.

关键词： paleostorms typhoon-induced deposits grain size loss on ignition Hainan Island

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Classifying the sedimentary environments of the Xincun Lagoon,Hainan Island,by system cluster and principal component analyses

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Acta Oceanologica Sinica 2017年第4期36卷 64-71页

作者： YANG Yang GAO Shu ZHOU liang WANG Yunwei li gaocong WANG Yaping HAN Zhuochen JIA Peihong State Key Laboratory for Estuarine and Coastal Research East China Normal University Ministry of Education Key Laboratory for Coast and Island Development Nanjing University College of Harbour Coastal and Offshore EngineeringHohai University

An understanding of the sedimentary environment in relation to its controlling factors is of great importance in coastal geomorphology,ecology,tourism and aquaculture studies.We attempt to deal with this issue,using a case study from the Xincun Lagoon,Hainan Island in southern China.For the study,surficial sediment samples were collected,together with hydrodynamic and bathymetric surveys,during August 2013.Numerical simulation was carried out to obtain high-spatial resolution tidal current data.The sediment samples were analyzed to derive mean grain size,sorting coefficient,skewness and kurtosis,together with the sand,silt and clay contents.The modern sedimentary environments were classified using system cluster and principal component analyses.Grain size analysis reveals that the sediments are characterized by extremely slightly sandy silty mud（ESSSM） and slightly silty sand（SSS）,which are distributed in the central lagoon and near-shore shallow water areas,respectively.Mean grain size varies from 0 to 8.0Ф,with an average of 4.6Ф.The silt content is the highest,i.e.,52% on average,with the average contents of sand and clay being 43% and 5%,respectively.There exists a significant correlation between mean size and water depth,suggesting that the surficial sediments become finer with increasing water depth.Cluster analyses reveals two groups of samples.The first group is characterized by mean grain size of more than 5.5Ф,whilst the second group has mean grain size of below 3.5Ф.Further,these groups also have different correlations between mean grain size and the other grain size parameters.In terms of the tidal current,the average values of the root mean square velocity（RMSV） are 7.5 cm/s and 6.9 cm/s on springs and neaps,respectively.For the RMSVs that are higher than 4 cm/s,a significant positive correlation is found between the content of the 63–125 μm fraction and the RMSV,suggesting that the RMSV determines the variability of the very fine sand fraction.Based on system cluster and principal component analyses

关键词： surficial sediment grain size lagoon sedimentary environment statistical analysis numerical simulation Hainan Island

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