检索结果-南通市图书馆

A 2-D HYDRODYNAMIC MODEL FOR THE river,LAKE AND network SYSTEM IN THE JINGJIANG REACH ON THE UNSTRUCTURED QUADRANGLES

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2010年第3期22卷 419-429页

作者： ZHANG Xi-bing HU De-chao WANG Min State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Wuhan430072 China Yangtze river Scientific Research Institute Wuhan 430010 China State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

The main river, the Dongting Lake and river networks in the Jingjiang reach of the Yangtze river constitute a complex water system, for which a full 2-D hydrodynamic model is established instead of the traditional 1-D or compound models for simulation of such complex systems, based on the latest developments of computer technologies and numerical methods. To better handle irregular boundaries and keep the computation cost well in a reasonable limit, unstructured grids of moderate scale are used. In addition, a dynamic boundary tracking method is proposed to simulate variable flow domains at different floods, especially, when the moderate scale gird can not describe flows in narrow river-network channels at low water levels. The t9 semi-implicit method and the Eulerian-Lagrangian Method （ELM） are adopted, which make the model unconditionally stable with respect to the gravity wave speed and Courant number restrictions. Properties and efficiency of the model are discussed, and it is concluded that the new model is robust and efficient enough for the simulation of a big, complex water system. Validation tests show that the simulation results agree well with field data. It takes about 0.96 h to complete the computation of a 76 d flood, which indicates that the model is efficient enough for engineering applications.

关键词： 2-D numerical model river network unstructured grid semi-implicit Eulerian-Lagrangian Method (ELM) boundarytracking

Distribution characteristics and controlling factors of typical antibiotics and antibiotic resistance genes in river networks in western area of Wangyu river,China

在线全文

学校读者我要写书评

暂无评论

Water Science and Engineering 2022年第4期15卷 318-327页

作者： Jing-jing Zhang Juan Chen Chao Wang Pei-fang Wang Han Gao Yu Hu Key Laboratory of Integrated Regulation and Resource Department on Shallow Lakes Ministry of EducationHohai UniversityNanjing 210098China College of Environment Hohai UniversityNanjing 210098China

Antibiotics and antibiotic resistance genes(ARGs)pose health risks in aquatic environments because of their persistence and *** networks can provide a perfect opportunity for exploring the occurrence and enrichment of ARGs and antibiotics in freshwater *** this basis,the abundances of four types of antibiotics(sulfonamides,quinolones,tetracyclines,and macrolides)and 13 ARGs(sulⅠ,sulⅡ,tetA,tetB,tetO,tetW,qnrA,qnrS,qnrD,ermB,ermF,ermC,and ere A)were measured in the river networks of the west bank of the Wangyu river in *** spatial distribution and temporal variation of these antibiotics and ARGs were characterized,and their controlling factors were *** four types of antibiotics were detected with high frequencies between 41%and 100%.Quinolone antibiotics exhibited the highest average concentration(286.53 ng/L).The concentrations of quinolones,tetracyclines,and macrolides were significantly higher in the winter than in the summer,whereas the concentration of sulfonamides was higher in wet periods than in dry *** the 13 ARGs,sulⅠwas the most abundant(1.28 x 10^(5)copies per milliliter),followed by sulⅡand tetO(5.41×10^(4)and 4.45×10^(4)copies per milliliter,respectively).The canonical correspondence analysis showed that environmental factors,including dissolved oxygen,water temperature,total nitrogen,pH,and total phosphorus,had significant effects on the abundance of ***Ⅰ,sulⅡ,tetA,and tetB were significantly correlated with 16S ribosomal RNA sequences,indicating that the bacterioplankton community might affect the distribution of *** correlation heat map analysis showed that the spread of ARGs was influenced by specific bacterial groups,such as Acidobacteria and Cyanobacteria,indicating that these bacterioplankton may be the hosts of environmental ARGs.

关键词： Wangyu river Antibiotic ARG Distribution characteristic Environmental factor river network

Solving the mystery of vanishing rivers in China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2019年第6期6卷 1239-1246页

作者： Yichu Wang Jinren Ni Yao Yue Jiaye Li Alistair G.L.Borthwick Ximing Cai An Xue Li Li Guangqian Wang The Key Laboratory of Water and Sediment Sciences Ministry of EducationCollege of Environmental Sciences and Engineering Peking University Beijing Innovation Center for Engineering Science and Advanced Technology Peking University State Key Laboratory of Plateau Ecology and Agriculture Qinghai University School of Water Resources and Hydropower Engineering Wuhan University State Key Laboratory of Hydroscience and Engineering Tsinghua University School of Engineering The University of Edinburgh Ven Te Chow Hydrosystems Lab Department of Civil and Environmental EngineeringUniversity of Illinois

A major controversy was sparked worldwide by a recent national water census claiming that the number of Chinese rivers with watersheds ≥100 km2was less than half the previous estimate of 50 000 rivers, which also stimulates debates on the potential causes and consequences. Here, we estimated the number of rivers in terms of stream-segmentation characteristics described by Horton, Strahler and Shreve stream-order rules, as well as their mixed mode for named rivers recorded in the Encyclopedia of rivers and Lakes in *** a result, the number of ‘vanishing rivers’ has been found to be highly relevant to statistical specifications in addition to the erroneous inclusion of pseudo-rivers primarily generated in arid or frost-thaw areas. The modified Horton stream-order scheme reasonably depicts the configuration of complete natural streams from headwater to destination, while the Strahler largely projects the fragmentation of the named river networks associated with human aggregation to the hierarchical river systems.

关键词： vanishing rivers river network stream segmentation stream-order rules

Relationship Between Changes of river-lake networks and Water Levels in Typical Regions of Taihu Lake Basin,China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Geographical Science 2012年第6期22卷 673-682页

作者： YIN Yixing XU Youpeng CHEN Ying Applied Hydrometeorological Research Institute Nanjing University of Information Science and Technology Nanjing 210044 China School of Geographic and Oceanographic Sciences Nanjing University Nanjing 210093 China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China College of Geographic Sciences Fujian Normal University Fuzhou 350007 China

The typical regions of the Taihu Lake Basin,China,were selected to analyze the variation characteristics of river-lake networks under intensive human *** characteristics of the fractal dimension of river networks and lakes for different periods were investigated and the influences of river system evolution on water level changes were further explored through the comparison of their fractal *** results are as follows:1) river network development of the study area is becoming more monotonous and more simple;the number of lakes is reducing significantly,and the water surface ratio has dropped significantly since the 1980s.2) The box dimension of the river networks in all the cities of the study area decreased slowly from the 1960s to the 1980s,while the decrease was significant from the 1980s to the *** variations of lake correlation dimension are similar to those of the river network box *** is unfavorable for the storage capacity of the river networks and lakes.3) The Hurst exponents of water levels were all between 0.5 and 1.0 from the 1960s to the 1980s,while decreased in the 2000s,indicating the decline in persistence and increase in the complexity of water level *** paper draws a conclusion that the relationship between the fractal dimension of river-lake networks and the Hurst exponents of the water level series can reveal the impacts of river system changes on flood disasters to some extent:the disappearance of river networks and lakes will increase the possibility of flood occurrence.

关键词： river network lake water level changes fractal Taihu Lake Basin

1-D NUMERICAL MODEL OF FLOW MOTION AND SUSPENDED-SEDIMENT TRANSPORTION IN river networkS OF THE PEARL river DELTA

在线全文

学校读者我要写书评

暂无评论

1-D NUMERICAL MODEL OF FLOW MOTION AND SUSPENDED-SEDIMENT TR...

Sediment transport following water transfer from Yangtze river to Taihu Basin

第九次河流泥沙国际学术大会

作者： Wei ZHANG Yixin YAN Yuliang ZHU and Jinhai ZHENGResearch Institute of Coastal and Ocean Engineering College Hohai University Nanjing 210098 China.

＜正＞The Pearl river Delta lies in the south of the GuangDong province of China. It is the river network area of the lower reaches of MaKou of Xijiang river, Sanshui of Beijiang river and ShiLong of Dongjiang river. The Pearl river Delta is the flood plain, among which Xijiang and Beijiang river Deltas include the river network area from Makou, Sanshui to the eight estuaries. The surface area of the Pearl river Delta is 9,750km2, among which Xijiang and Beijiang river Delta is about 8,370 km2, accounting for 85.8% of the whole delta, and Dongjiang river Delta is 1,380 km2, accounting for 14.2%. rivers in this area interlace each other, and the river current is affected prominently by the tides. Based on the Saint-Venant equations and the non-equilibrium transport equation for the suspended-sediment, a numerical model of junction- river course for the whole Pearl river Delta is established in this paper by using the junction-control methods for water level and sediment concentration. Firstly, the river network in the Pearl river Delta is schematized as 340 main river courses, 216 nodes and 1,850 cross sections. The area of river network in this model is about 2,000km2, and the total length is more than 1,600km. Secondly, the equations are divided into three steps as the river sections, river courses and the branch nodes. The algorithm for the sediment transport in the river networks is similar to that for unsteady flow. Finally the water level, flux, and sediment concentration at every section in the river network are calculated. Representative period field data are used to verify the model. It is testified that the calculation agrees with the observed data.

关键词： Pearl river Delta river network Junction-control method Numerical model

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Water Science and Engineering 2011年第4期4卷 431-444页

作者： Zheng GONG Chang-kuan ZHANG Cheng-biao ZUO Wei-deng WU State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 P. R. China Laboratory of Ocean Dynamics ：Third Institute of Oceanography State Oceanic Administration Xiamen 361005 P. R. China

To meet the increasing ：need of fresh water and to improve the water quality of Taihu Lake, water transfer from the Yangtze river was initiated in 2002. This study was performed to investigate the sediment distribution along the river course following water transfer. A rainfall-runoff model was first built to calculate the runoff of the Taihu Basin in 2003. Then, the flow patterns of river networks were simulated using a one-dimensional river network hydrodynamic model. Based on the boundary conditions of the flow in tributaries of the Wangyu river and the water level in Taihu Lake, a one-dimensional hydrodynamic and sediment transport numerical model of the Wangyu river was built to analyze the influences of the inflow rate of the water transfer and the suspended sediment concentration （SSC） of inflow on the sediment transport. The results show that the water transfer inflow rate and SSC of inflow have significant effects on the sediment distribution. The higher the inflow rate or SSC of inflow is, the higher the SSC value is at certain cross-sections along the ：river course of water transfer. Higher inflow rate and SSC of inflow contribute to higher sediment deposition per kilometer and sediment thickness. It is also concluded that a sharp decrease of the inflow velocity at the entrance of the Wangyu river on the river course of water transfer induces intense sedimentation at the cross-section near the Changshu hydro-junction. With an increasing distance from the Changshu hydro-junction, the sediment deposition and sedimentation thickness decrease gradually along the river course.

关键词： Taihu Basin Taihu Lake river network water transfer rainfall-runoff model 1-D hydrodynamic numerical model cohesive sediment