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Morphologic evolution of bifurcated reaches in a macrotidal estuary with mountain streams

International Journal of Sediment Research 2022年第6期37卷 857-870页

作者： Jing Liu Yongjun Lu Liqin Zuo Huaixiang Liu Qun Xu Qingzhi Hou State Key laboratory of hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research Institute Department of College of Water Conservancy and Hydropower Engineering Hohai University Yangtze Institute for Conservation and Development

A macrotidal estuary with mountain streams(MEMS) is characterized by rapidly rising and falling flood peaks and large tidal ranges and is a typical estuary type with strong flow dynamics that is found worldwide. Understanding the morphodynamic evolution of MEMSs has great significance for river management. The roles of the mountain stream river flood process and macrotides on the morphology evolution still needs further quantitative study. Taking the Oujiang Estuary as an example, the evolution mechanisms of bifurcated reaches of a MEMS are studied by analyzing the hydrologic and topographic data and using a two-dimensional numerical model for flow-sediment transport. The results show that(1) under the combined actions of runoff and macrotides, sediment transport is active and morphological evolution is intensive, the main branch and subbranch historically switch frequently, and erosion generally occurs in wet years, while deposition occurs in dry years.(2) The river flood process of mountain streams causes rapid erosion, which rises and falls rapidly with a kurtosis index(K) of approximately 2.9. There is a logarithmic relation between the sediment transport load and K. The volume of sediment transport will be 40% larger than the river flood process with K = 1.2 as for the Yangtze River.(3) Macrotides with large tidal ranges could enhance the discharge asymmetry(ψ).When the ψ is greater than 1, the side branches are dominated by flood tides. Although the current study is site specific, the results are expected to provide a valuable reference for sustainable management in similar estuaries.

关键词： Mountain stream Macrotide Kurtosis index of river flooding Tide asymmetry Morphological evolution Bifurcated reach

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Measurement of particle size based on digital imaging technique

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Journal of Hydrodynamics 2013年第2期25卷 242-248页

作者：陈红唐洪武刘云王浩刘贵平 State Key laboratory of hydrology-Water Resources and Hydraulic Engineering Hohai University

To improve the analysis methods for the measurement of the sediment particle sizes with a wide distribution and of irregular shapes, a sediment particle image measurement, an analysis system, and an extraction algorithm of the optimal threshold based on the gray histogram peak values are proposed. Recording the pixels of the sediment particles by labeling them, the algorithm can effectively separate the sediment particle images from the background images using the equivalent pixel circles with the same diameters to represent the sediment particles. Compared with the laser analyzer for the case of blue plastic sands, the measurement results of the system are shown to be reasonably similar. The errors are mainly due to the small size of the particles and the limitation of the apparatus. The measurement accuracy can be improved by increasing the Charge-Coupled Devices （CCD） camera resolution. The analysis method of the sediment particle images can provide a technical support for the rapid measurement of the sediment particle size and its distribution.

关键词： particle size extraction algorithm of optimal threshold equivalent circle transformation

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Experimental Study on Scouring and Silting Deformation of Artificial Beach Under Storm Surge−Wave Coupling

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China Ocean Engineering 2022年第1期36卷 65-75页

作者： SUN Tian-ting HU Po PAN Jun-ning HOU Yi-jun MO Dong-xue WANG Deng-ting Nanjing Hydraulic Research Institute Nanjing 210029China State Key laboratory of hydrology-Water Resources and Hydraulic Engineering Nanjing 210029China Key laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of SciencesQingdao 266071China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China laboratory for Ocean and Climate Dynamics Qingdao National Laboratory for Marine Science and TechnologyQingdao 266237China

With the increasing construction of artificial beach in coastal areas, it is of practical significance to study the beach surface deformation of artificial beach profile. Previous studies only focus on a single wave dynamic factor, and it is difficult to predict the beach deformation of artificial beach profile under the storm surge-wave co-action. To solve this problem, the cross-section physical model test method was used to study the beach surface deformation of a typical artificial beach profile in Shuangdao Bay, Weihai, Shandong Province, after continuous wave actions till they stabilize. The characteristics of beach surface deformation under the conditions of constant water levels, laddershaped water level combined with corresponding wave elements and storm surge-wave co-action are compared and analyzed. A beach profile model which satisfies the theory of Bruun model is proposed. The test results show that the maximum scour depth of beach under storm surge-wave co-action is smaller and the scour range is obviously larger than that under the condition of constant water levels or ladder-shaped water level. The evaluation of the maximum scour depth by traditional model test tends to be conservative while the evaluation of the scour range is *** research results can provide scientific reference for designing artificial beaches.

关键词： artificial beach scouring and silting deformation profile shape physical model tests storm surge-wave coupling

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Evaluation of latest TMPA and CMORPH satellite precipitation products over Yellow River Basin

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Water Science and Engineering 2016年第2期9卷 87-96页

作者： Shan-hu Jiang Meng Zhou Li-liang Ren Xue-rong Cheng Peng-ju Zhang State Key laboratory of hydrology-Water Resources and Hydraulic Engineering Hohai University College of hydrology and Water Resources Hohai University

The main objective of this study was to evaluate four latest global high-resolution satellite precipitation products(TMPA 3B42 RT, CMORPH,TMPA 3B42V7, and CMORPH_adj) against gauge observations of the Yellow River Basin from March 2000 to December 2012. The assessment was conducted with several commonly used statistical indices at daily and monthly scales. Results indicate that 3B42V7 and CMORPH_adj perform better than the near real-time products(3B42RT and CMORPH), particularly the 3B42V7 product. The adjustment by gauge data significantly reduces the systematic biases in the research products. Regarding the near real-time datasets, 3B42 RT overestimates rainfall over the whole basin, while CMORPH presents a mixed pattern with negative and positive values of relative bias in low- and high-latitude regions,respectively, and CMORPH performs better than 3B42 RT on the whole. According to the spatial distribution of statistical indices, these values are optimized in the southeast and decrease toward the northwest, and the trend is similar for the spatial distribution of the mean annual precipitation during the period from 2000 to 2012. This study also reveals that all the four products can effectively detect rainfall events. This study provides useful information about four mainstream satellite products in the Yellow River Basin, and the findings can facilitate the use of global precipitation measurement(GPM) data in the future.

关键词： Satellite precipitation TMPA CMORPH Yellow River Basin

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Temporal and spatial variations of bacterial community compositions in two estuaries of Chaohu Lake

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Journal of Oceanology and Limnology 2020年第3期38卷 745-758页

作者： ZHANG Lei LI Li LIU Mengna HU Yao JIANG Jiahu State Key laboratory of Lake Science and Environment Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008 School of Civil Engineering and Architecture Chuzhou UniversityChuzhou 239000China

The distinctive estuary hydrodynamics and nutrient input make the estuary ecosystem play a key role in lake *** Nanfei River and Zhaohe River are two main inlets of Chaohu Lake,Anhui,East *** selected estuaries of the two rivers as representative areas to study temporal and spatial changes of bacterial *** August(summer)and November(autumn)2016 and February(winter)and May(spring)2017,16 water and sediment samples were collected from the *** characteristics indicate significant differences in the nutritional status and eutrophication index of the estuaries due mainly to organic *** of the number of operational taxonomic units,the diversity index,the community composition,and redundancy analysis revealed the ***,the existence of varying degrees of seasonal differences in the distribution of almost all *** addition,the species diversity in the sediment samples was higher than that in the water samples,and the dominant species differed also among these ***,a large number of unknown genera were detected,especially in the sediment samples,such as unclassified Xanthomonadales incertae sedis,unclassified Anaerolineaceae,and unclassified ***,TP,TN,and TOC were the main influential factors that affected the bacterial community structure.

关键词： estuary water and sediment bacterial diversity bacterial community structure

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Relationship between adjustment of low water level and utilization of water depth in Shashi Reach in middle Yangtze River

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Water Science and Engineering 2022年第2期15卷 114-124页

作者： Juan-juan Fang Yun-ping Yang Meng-lin Jia Yu-de Zhu Jian-jun Wang State Key laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China Tianjin Research Institute for Water Transport Engineering Ministry of TransportTianjin 300456China State Key laboratory of hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing 210098China

Hydrological,sediment,and bathymetric data of the Shashi Reach in the middle Yangtze River for the period of 1975-2018 were collected,and the characteristics of low water level changes and their impacts on utilization of water depth for navigation were *** results showed that,during the study period,the Shashi Reach riverbed was significantly scoured and incised,with cross-sectional profiles showing overall narrowing and *** indicated a strong potential to improve the water depth of the *** analysis of the temporal variation of in-channel topographical features showed that the Taipingkou diara underwent siltation and erosion,with its head gradually scoured and relocated downstream after 2008,and the Sanbatan diara continued to shrink and migrate *** water levels with the same flow rate over the study period *** instance,from 2003 to 2020,the water level at the Shashi hydrological station decreased to 1.37 m with a flow rate of 6000 m^(3)/***,the designed minimum navigable water level of the Shashi Reach was approximately 2.11m lower than the recommended *** terms of utilization of the channel water depth,continuous scouring of the river channel is expected to result in a reduction in discharge at the Taipingkou mouth,which will improve the water depth conditions of the channel during the dry season in the Shashi *** several channel regulation projects,the 3.5-m depth of the Shashi Reach would basically be *** promotes utilization of the shipping route from the Taipingkou south branch to the Sanbatan north branch as the main navigation channel during the dry *** the factors of current water depth and the clear width limitation of the navigation hole at the Jingzhou Yangtze River Bridge,this route can still be favored as the main navigation channel with a 4.5-m depth during the dry season.

关键词： Low water level Shoal evolution Channel water depth utilization Shashi Reach Yangtze River

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Synthesis, Structure and Properties of a Strontium(Ⅱ) Complex with 2, 3-Pyrazinedicarboxylic Acid

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Chinese Journal of Structural Chemistry 2012年第10期31卷 1447-1454页

作者：李会会吴刚郭莉 College of Material and Chemical Engineering Chuzhou University State Key laboratory of Coordination Chemistry Nanjing University

Complex [Sr2（pdc）2（H2O）7]·H2O （1, H2pdc = 2,3-pyrazinedicarboxylic acid） has been synthesized and characterized by single-crystal X-ray diffraction studies and FT-IR. Structural determination reveals that there are two crystallographically independent strontium ions in 1. The coordination geometry of Sr（1） is a nine-coordinated distorted monocapped tetragonal antiprism, while Sr（2） is a nine-coordinated distorted monocapped tetragonal prism. The ligand pdc2- takes two different connecting modes and links St（If） centers to generate a 2D layer structure. The 2D layers are linked through O-H...O and O-H...N hydrogen bonds to form a 3D framework structure. Thermal stability and luminescent properties of complex 1 are investigated. 1 belongs to the monoclinic system, space group P21/n with a = 10.7182（10）, b = 7.0377（6）, c = 29.225（3） A, β = 95.7170（10）°, Z = 4, V = 2193.5（3） A3, Mr = 651.56, Dc = 1.973 g/cm3, F（000） = 1296,μ = 4.951 mm-1, the final R = 0.0318 and wR = 0.0726 for 3938 observed reflections with I 〉 2σ（/）.

关键词： Sr(Ⅱ) complex carboxylate group luminescent property thermal stability

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Processes,feedbacks,and morphodynamic evolution of tidal flat-marsh systems:Progress and challenges

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Water Science and Engineering 2022年第2期15卷 89-102页

作者： Zeng Zhou Meng-jiao Liang Lei Chen Meng-piao Xu Xue Chen Liang Geng Huan Li Daniel Serrano He-yue Zhang Zheng Gong Chang-kuan Zhang State Key laboratory of hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing 210098China Jiangsu Key laboratory of Coast Ocean Resources Development and Environment Security Hohai UniversityNanjing 210098China Department of Civil Environmental and Architectural EngineeringUniversity of PaduaPadua 35122Italy

Tidal flats and saltmarshes have been a long-standing research focus because of their high socio-economic and ecological *** evolution of tidal flat-marsh systems is highly complex due to the intertwined processes operating over a variety of spatial and temporal *** a traditional research highlight,the role of regular hydrodynamic processes such as tides,waves,and river flows have been explored comprehensively with fruitful *** past decades,the changing environment(e.g.,sea level rise,increasing anthropogenic activities,and extreme weather conditions)has attracted more attention with many reported insightful *** recent advances indicate that biological activities play a critical role in tidal flat-marsh morphodynamics but are still poorly *** field of research that connects the bio-logical and physical processes is commonly described as"biogeomorphology"and requires the joint efforts by scientists from multiple dis-ciplines ranging from hydraulics,ecology,and geography to *** review aims to provide a synthesis of the current research status of tidal flat-marsh morphodynamics,with a particular emphasis on the understanding of various processes and feedbacks underlying the devel-opment of morphodynamic *** future research needs and challenges are identified to facilitate a more sustainable management strategy for tidal flats and saltmarshes under climate change.

关键词： Tidal flats Coastal wetlands Morphodynamics Saltmarshes Tidal channels Morphodynamic modeling

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Impacts of permafrost degradation on streamflow in the northern Himalayas

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Science China Earth Sciences 2024年第6期67卷 1990-2000页

作者： Linfeng FAN Fang JI Xingxing KUANG Zhilin GUO Rui ZHANG Chunmiao ZHENG State Key laboratory of Mountain Hazards and Engineering Resilience Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610299China Yangtze Institute for Conservation and Development Hohai UniversityNanjing 210024China School of Environmental Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Eastern Institute for Advanced Study Ningbo 315200China

The Himalayan water tower provides crucial water resources for *** degradation is deemed to exert important impacts on streamflow in the Himalayan ***,the magnitudes of such impacts remain poorly ***,we established a robust hydrological model that incorporated active layer deepening and ground ice melt for the drainage basin of the largest river in the northern Himalayas-the Yarlung Zangbo River(YZR).We estimated that permafrost degradation led to~0.65 km^(3)/yr decrease in surface runoff and~0.35 km^(3)/yr increase in baseflow and ground ice melt contributed~0.25% to the annual streamflow in the YZR for the period ***“fill-and-spill”mechanism helps explain the seeming contradiction of observed increasing versus decreasing baseflow in different permafrost regions *** propose that the dilution of riverine dissolved organic carbon(DOC)concentrations by baseflow may lead to the riverine DOC hysteresis *** study not only lays solid scientific basis for water resources management in the Himalayas,but also yields new insights into how to interpret measured river discharge and nutrient flux in permafrost regions over the globe.

关键词： Permafrost degradation hydrology Streamflow Surface runoff Groundwater Himalayas

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Verification of A Numerical Harbour Wave Model

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China Ocean Engineering 2007年第4期21卷 647-658页

作者：潘军宁洪广文左其华王登婷 State Key laboratory of hydrology-Water Resources and Hydraulic Engineering Hohai University State Key laboratory of hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research Institute

A numerical model for wave propagation in a harbour is verified by use of physical models. The extended time-dependent mild slope equation is employed as the governing equation, and the model is solved by use of ADI method containing the relaxation factor. Firstly, the reflection coefficient of waves in front of rubble-mound breakwaters under oblique incident waves is determined through physical model tests, and it is regarded as the basis for simulating partial reflection boundaries of the numerical model. Then model tests on refraction, diffraction and reflection of waves in a harbour are performed to measure wave height distribution. Comparative results between physical and numerical model tests show that the present numerical model can satisfactorily simulate the propagation of regular and irregular waves in a harbour with complex topography and boundary conditions.

关键词： wave mild slope equation numerical model harbour verification

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