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International Journal of Sediment research 2013年第4期28卷 496-510页

作者： Yan-yan ZHANG De-yu ZHONG Bao-sheng WU State Key Laboratory of Hydroscience and Engineering Tsinghua University pearl River Hydraulic research institute Pearl River Water Resources Commission

This paper presents a study on the characteristics of multiple time scales of bankfull discharge and its delayed response to changes of tlow conditions using continuous wavelet analysis for data from selected hydrologieal stations in the Yellow River *** showed that bankfull discharge series had one or two dominant lime *** example,the Huayuankou station in the lower reach of the Yellow River had two dominant time scales of 19 20 years and 5 6 *** dominant time seales of the bankfull discharge series were generally consistent with the dominant time scales of water discharge and sediment concentration series,indicating thai the channel morphology inherits the characteristics of the hydrologieal system in terms of multiple time *** addition,the wavelet coefficients of the bankfull discharge series had a phase difference in relation to those of the sediment concentration series,with a delay time that varied from 3 to 16 years at different *** delay time or relaxation lime is a result of the delayed response of bankfull discharge to How conditions,which was significant for channel adjustments in response lo changes of tlow *** findings of the multiple lime scales and the delayed response are of importance for further study of channel morphology of fluvial systems.

关键词： Multiple time scales wavelet analysis bankfull discharge river morphology fluvial processes Yellow River

Channelized and unchannelized collapses of granular columns on a horizontal surface

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Journal of Mountain Science 2020年第12期17卷 2982-2996页

作者： ZHANG Quan HUANG Bo-lin ZHAO Hai-lin CHEN Xiao-ting LUO Chao-lin Hubei Key Laboratory of Disaster Prevention and Mitigation China Three Gorges UniversityYichang 443002China pearl River Water resources research institute Pearl River Water Resources Research InstituteGuangzhou 510611China

Columnar dangerous rock mass is widely developed in many high and steep mountain areas around the *** often collapses,disintegrates and produces debris flow,which is *** collapse process of the columnar dangerous rock mass is very similar to the collapse of granular *** this paper,we report the results of an experimental investigation of the flow induced by the collapse of a column of granular material over a horizontal *** different setups are used,namely,a channelized granular column collapse(i.e.,two-dimensional) and an unchannelized granular column collapse(i.e.,three-dimensional),allowing us to compare channelized and unchannelized collapses *** experimental data suggest that our experimental findings were markedly different from those reported by previous authors(i.e.,include the channelized and unchannelized collapse flows showed differences in energy conversion and dissipation).In channelized collapse flows,the maximum vertical speed appears in the free fall regime,while,the maximum speed in the vertical direction of unchannelized collapse flows appears in the spreading *** the whole collapse process,i.e.,in channelized and unchannelized collapse flows,the conversion of potential energy and kinetic energy does not occur uniformly,and the maximum kinetic energy of the channelized collapse flows is higher than that of the unchannelized collapse flows,and compared with the unchannelized collapse flows,the dissipation energy in the channelized collapse flows is lower.A series of experiments was performed to predict the behaviour of different granular columns(characterized by different initial aspect ratio(a),varying from 1 to 4).The data obtained from 2 D experimental model and3 D experimental model have certain amount of difference,such as the particle runout distance(d1),the maximum central height(h2),and the deposition angle(i.e.,β1,β2).These differences show that the 2 D experimental model does not fully represen

关键词： Granular column Unchannelized collapses flows Energy conversion Energy dissipation Deposition prediction Gravity height Deposition angle

Experimental study on flocculation and sedimentation characteristics of cohesive fine sediment measured using ultrasound in the pearl River Estuary

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International Journal of Sediment research 2023年第6期38卷 880-890页

作者： Qinqin Liu Xiaojian Liu Jian Chen Peng Hou Yong He Qisong Wang Xiaowei Zhu Qiang Wang Huan Gao pearl River Hydraulic research institute Pearl River Water Resources Commission of the Ministry of Water Resources Key Laboratory of the pearl River Estuary Regulation and Protection of the Ministry of Water resources School of Water Conservancy North China University of Water Resources and Electric Power Department of the College of Water Conservancy and Hydropower Engineering Hohai University

Flocculation-settling of cohesive fine sediment is the main cause of sediment deposition and changes in topography and geomorphology in ***,studies on estuary morphology have often focused on a single influencing factor,and sediment deposition characteristics under disturbances in sediment concentration,moisture content,and external forces have rarely been considered *** authors propose an ultrasound-assisted flocculation-settling method to analyze the various factor affecting cohesive *** current study examined the sedimentation patterns of cohesive sediment with a sediment content concentration of 30%-80% through ultrasound *** results show that when the sediment concentration is 40%-50%,the best effect on flocculation and sedimentation is induced by ultrasound *** corresponding settling height at the clear-muddy water interface is 3.05-3.45 cm,and the settling rate is 0.161-0.173 cm/***,using ultrasound waves,a moisture content of the sediment concentration of 30%-80% was analyzed based on wet and dry *** a sediment concentration of 50% as an example,the maximum values of the variation in the water contents of the upper,middle,and lower layers of the wet basis were 0.82%,0.51%,and0.37%,respectively,whereas those of the upper,middle,and lower layers of the dry basis were 4.77%,1.07%,and 0.60%,***,the moisture content of dry and wet sediment varied as follows:Wupper> Wmiddle> *** current research results can provide a theoretical basis and technical reference for siltation in channels,harbors,and reservoirs;the evolution of submarine deltas and coastal beaches;transportation of fluid mud;and the treatment of hyper-concentrated sediment flows.

关键词： Cohesive sediment Flocculation-settling Moisture content Ultrasound experiments

MDSNet:a multiscale decoupled supervision network for semantic segmentation of remote sensing images

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International Journal of Digital Earth 2023年第1期16卷 2844-2861页

作者： Jiangfan Feng Panyu Chen Zhujun Gu Maimai Zeng Wei Zheng School of Computer Science and Technology Chongqing University of Posts and TelecommunicationsChongqingPeople’s Republic of China pearl River Water resources research institute Pearl River Water Resources CommissionGuangzhouPeople’s Republic of China

Recent deep-learning successes have led to a new wave of semantic segmentation in remote sensing(RS)***,most approaches rarely distinguish the role of the body and edge of RS ground objects;thus,our understanding of these semantic parts has been frustrated by the lack of detailed geometry and *** we present a multiscale decoupled supervision network for RS semantic *** proposed framework extends a densely supervised encoder-decoder network with a feature decoupling module that can decouple semantic features with different scales into distinct body and edge *** further conduct multiscale supervision of the original and decoupled body and edge features to enhance inner consistency and spatial boundaries in remote sensing image(RSl)ground objects,enabling new segmentation designs and semantic components that can learn to perform multiscale geometry,and *** results outperform the previous algorithm and are robust to different *** results demonstrate that decoupled supervision is an effective solution to semantic segmentation tasks of RS images.

关键词： Semantic segmentation remote sensing images edge supervision multiscale

EXPERIMENTAL INVESTIGATION OF EFFECT OF TIDE ON COASTAL GROUNDWATER TABLE

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Journal of Hydrodynamics 2010年第1期22卷 66-72页

作者： WU Longohua ZHUANG Shui-ying Center for Eco-Environmental Modeling Hohai University Nanjing 210098 China pearl River Water resources Scientific research institute Guangzhou 510611 China

In this article, a tide simulation system based on a two-way water pump technique is developed. Using this system and numerical simulations, the groundwater table fluctuation characteristics, relative over height of groundwater table, and influencing factors of over height are investigated. The experimental and numerical results indicate that the groundwater table fluctuation is of periodic, and of asymmetric. The amplitude of groundwater table fluctuations decreases with the increase of the onshore distances. There are phase lags of groundwater table fluctuations for different monitoring points. The tide can bring about remarkable over height of coastal groundwater table. The dominating factors bring about over height include the tide amplitude, aquifer thickness and tide frequency. Under experimental conditions, the relative tide amplitude over height may exceeded 50% of the maximal tide amplitude, and reach about 10% of aquifer thickness.

关键词： tide simulation system coastal aquifer groundwater table over height

Instantaneous sediment transport formula for sheet flow beneath asymmetric wave and current

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Journal of Hydrodynamics 2022年第4期34卷 712-724页

作者： Xin-yu Hu Zhong-hua Weng Xin Chen Hai-fei Liu The Key Laboratory of Water and Sediment Sciences of Ministry of Education School of EnvironmentBeijing Normal UniversityBeijing100875China pearl River Water resources research institute Pearl River Water Resources CommissionGuangzhou 510611China College of Water resources and Civil Engineering China Agricultural UniversityBeijing 100083China

An instantaneous formula is obtained for the sheet flow transport beneath the wave and the current by a product integration of the concentration and velocity profiles over the mobile seabed. The formula involves: (1) The product of the erosion depth and the free stream velocity, which can be reduced to the Shields parameter of power 3/2 in accordance with the classical formulae. (2) The ratio of the wave boundary layer thickness to the erosion depth. The formula incorporates the effects of the acceleration and the phase lag on the erosion depth, the asymmetric wave boundary layer and the wave-current interaction. The validation of the formula is made by the data obtained from the oscillatory tunnels covering a wide range of wave-current and sediment conditions. The instantaneous sediment transport rate is compared with the power function of the velocity with different exponents. The formula consists of a wave force part and a current force part and their relative importance depends on the wave shapes. The present formula gives very good results for the net sediment transport as compared to several existing steady and unsteady formulae. The net sediment transport rates are affected by not only the acceleration, the phase lag and the wave-current interaction, but also the asymmetric boundary layer development.

关键词： Boundary layer thickness erosion depth instantaneous formula sediment transport rate wave and current

Flume experimental study on evolution of a mouth bar under interaction of floods and waves

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Water Science and Engineering 2019年第2期12卷 162-168页

作者： Li Yan Men-wu Wu Ying Chen Yao Wu Tian-sheng Wu pearl River Hydraulic research institute Pearl River Water Resources CommissionGuangzhou 510611China Key Laboratory of the pearl River Estuarine Dynamics and Associated Process Regulation Ministry of Water ResourcesGuangzhou 510610China College of Harbor Coastal and Offshore EngineeringHohai UniversityNanjing 210098China

Based on the characteristics of hydrodynamics and sediment transport in the bar area in the Modaomen Estuary,a flume experiment was performed to study the evolution of the longitudinal profile of the mouth *** mouth bar evolution was investigated under the impacts of floods with different return periods as well as flood-wave *** results showed that floods with different return periods had significant influences on the evolution of the river mouth *** on the inner slope of the mouth bar,the sediment was substantially active and *** inner slope and the bar crest tended to be remarkably *** erosion was intensified with the increase of the magnitude of ***,the bar crest moved seawards,while the elevation of the bar crest barely *** the flood-wave interaction,a remarkable amount of erosion on the inner and outer slopes of the mouth bar was also *** seaward displacement of the bar crest under the interaction of floods and waves was less than it was under only the impact of floods,while more deposition was found on the crest of the mouth bar in this case.

关键词： Modaomen Mouth bar Wave Flood Flume experiment Sediment transport

Sewage sludge ditch for recovering heavy metals can improve crop yield and soil environmental quality

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Frontiers of Environmental Science & Engineering 2021年第2期15卷 65-75页

作者： Xianke Lin Xiaohong Chen Sichang Li Yangmei Chen Zebin Wei Qitang Wu Key Laboratory of Soil Environment and Waste Reuse in Agriculture of Guangdong Higher Education institutes College of Natural Resources and EnvironmentSouth China Agricultural UniversityGuangzhou 510642China Key Laboratory of the pearl River Estuarine Dynamics and Associated Process Regulation Ministry of Water ResourcesPearl River Hydraulic Research InstitutePearl River Water Resource CommissionGuangzhou 510611China

The treatment and disposal of municipal sewage sludge(MSS)is an urgent problem to be resolved in many *** using the nutrients within MSS to increase crop yield and enhance the fertility of poor soil could contribute to achieving sustainable *** indirect use of MSS in ditches alongside Pennisetum hybridum plants was studied in field plots for 30 months and the contents of heavy metals and macronutrients were monitored in soil,sludge and plant *** found that the yield of *** was significantly increased by 2.39 to 2.80 times and the treated plants had higher N content compared with no *** addition,the organic matter(OM)and N contents in the planted soil increased significantly compared with the initial *** OM content in the planted soil of the MSS treatment was 2.9 to 5.2 times higher than that with no sludge,and N increased by 2.0 to 3.8 ***,MSS had no significant effect on the N,P and K contents in the soil at the bottom of the MSS ditch,and the content of heavy metals(Cd,Pb,Cu and Zn)were also within the safe ***,the moisture content and phytotoxicity of MSS after this indirect use were reduced and the heavy metal contents changed little,which is favorable to the further disposal of recovered ***,this indirect use of MSS is beneficial to agricultural production,soil quality and environmental sustainability.

关键词： Municipal sewage sludge Indirect use Heavy metals Macronutrients Pennisetum hybridum

The energy budget under the influence of topography in the Zhujiang River Estuary in China

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Acta Oceanologica Sinica 2015年第1期34卷 148-158页

作者： LIU Huan WU Chaoyu WU Yaju School of Marine Science Sun Yat-sen University research Center of Coastal Ocean Science and Technology Sun Yat-sen University Guangdong Provincial Key Laboratory of Marine resources and Coastal Engineering Sun Yat-sen University pearl River Hydraulic research institute Pearl River Water Resources Commission

The Zhujiang River （pearl River） Estuary （ZRE） is a very complicated and large-scale estuarine system in China. It consists of two parts： the river networks and the estuarine bays. Not only is the network system one of the most complicated in the world, but also each estuarine bay has a very special morphodynamic feature due to the geological settings. Morphological boundary conditions have direct effects on the energy dissipa- tion and balance. On the basis of a three-dimensional （3-D） barotropic model whose domain includes the river networks and the estuarine bays, the energy budget is discussed under the influence of topography in the ZRE. The elevation and discharge of this model are validated by the observations collected in July 1999 and February 2001. The results show that （1） the source of energy in the ZRE is mainly generated by tides and river runoffs, which have an obvious seasonal change, and （2） there are some typical hotspots where the energy dissipation is 1-2 orders higher than those in the immediate upstream and downstream sections in the ZRE. These hotspots are linked with the small-scale dynamic structures （SSDS） and morphological units. On the basis of the characteristics of the morphology and the energy dissipation, the hotspots can be catego- rized into three types： the outlet of the ZRE, the meandering river, the branch and junction.

关键词： three-dimensional barotropic model energy dissipation momentum balance topography,Zhuijang River (pearl River) Estuary

Energy conversion and deposition behaviour in gravitational collapse of granular columns

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Journal of Mountain Science 2020年第1期17卷 216-229页

作者： HUANG Bo-lin WANG Jian ZHANG Quan LUO Chao-lin CHEN Xiao-ting Hubei Key Laboratory of Disaster Prevention and Mitigation China Three Gorges UniversityYichang 443002China National Observatory of the Three Gorges Landslide Yangtze RiverHubei ProvinceChina Three Gorges UniversityYichang 443002China pearl River Water resources research institute Pearl River Water Resources Research InstituteGuangzhou 510611China

The high-density gravitational collapse of granular columns is very similar to the movements of large collapsing columns in nature. Based on the development of dangerous columnar rock mass in fields, granular column collapse boundary condition in the physical experiments of this study is a new type of boundary conditions with a single free face and a three-dimensional deposit. Physical experiments have shown that the mobility of small particles during the collapse of granular columns was greater than that of large particles. For example, when particle size was increased from 5 to 15 mm, deposit runout was decreased by about 16.4%. When a column consisted of two particle types with different sizes, these particles could mix in the vicinity of layer interfaces and small particles might increase the mobility of large particles. In the process of collapse, potential and kinetic energy conversion rate is fluctuated. By increasing initial aspect ratio a, the ratio of the initial height of column to its length along flow direction,potential and kinetic energy conversion rate is decreased. For example, as a was increased from 0.5 to 4, the ratio of maximum kinetic energy obtained and total potential energy loss was decreased from47.6% to 7.4%. After movement stopped, an almost trapezoidal body remained in the column and a fanlike or fan-shaped accumulation was formed on the periphery of column. Using multiple exponential functions of the aspect ratio a, the planar morphology of the collapse deposit of granular columns could be quantitatively characterized. The movement of pillar dangerous rock masses with collapse failure mode could be evaluated using this granular column experimental results.

关键词： Granular columns Rock collapse Collapse experiments Energy conversion Deposit sequence Deposit prediction