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Effects of landuse change on surface runoff and sediment yield at different watershed scales on the Loess Plateau

International Journal of Sediment Research 2010年第3期25卷 283-293页

作者： ZHANG Xiaoming1, CAO Wenhong2, GUO Qingchao3, and WU Sihong41 assoc. prof. dr., China Institute of Water Resources and Hydr.power Research, Beijing 100048, China, 2,3 prof. dr., China Institute of Water Resources and Hydr.power Research, Beijing 100048, China, 4 dr., Department of Land and Water Resources Engineering, Royal Institute of Technology, Stockholm, SE-100 44, Sweden assoc. prof. dr. China Institute of Water Resources and Hydropower Research Beijing 100048 China prof. dr. China Institute of Water Resources and Hydropower Research Beijing 100048 China dr. Department of Land and Water Resources Engineering Royal Institute of Technology Stockholm SE-100 44 Sweden

Erosion and sediment yield from large and small watersheds exhibit different laws. Variations in surface runoff and sediment yield because of landuse change in four watersheds of different scales from 1 km2 to 73 km2 were analyzed. Due to reforestation and farmland terracing, surface runoff and sediment yield reduced by 20-100% and 10-100% respectively. Reductions in surface runoff were differed significantly under different precipitation regimes. For the large watershed (73 km2) landuse change had similar effects on surface runoff regardless of changing of precipitation. For the small watershed (1 km2) landuse change had fewer effects on surface runoff under high precipitation. The relative changes of sediment yield in the four watersheds under reforestation and farmland terracing decreased as precipitation increased from 350 mm to 650 mm, then increased as precipitation increased from 650 mm to 870 mm. Where initial forest coverage rate was below 45%, sediment yield decreased dr.matically as forest coverage rate increased. Watershed management with aiming at reducing both surface runoff and sediment yield should be conducted both on sloping surfaces and in channels in large watersheds.

关键词： Soil erosion Land use change Scale effect Surface runoff and sediment yield Watershed Loess Plateau

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Revisited Vanoni-Brooks sidewall correction

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International Journal of Sediment Research 2011年第4期26卷 524-528页

作者： Nian-Sheng CHENG 1 assoc.prof.School of Civil and Environmental Engineering,Nanyang Technological University,Nanyang Avenue,Singapore 639798. assoc. prof. School of Civil and Environmental Engineering Nanyang Technological University Nanyang Avenue Singapore 639798

The evaluation of the sidewall friction could be inconvenient in the implement of the Vanoni-Brooks sidewall correction *** the Colebrook-White equation and Nikuradse’s pipe friction data,two explicit formulae are developed in this note for finding the sidewall friction *** are applicable for various sidewalls that are either hydr.dynamically-smooth or rough,or in the transitional regime.

关键词： Sidewall correction Friction factor Open channel flow Pipe flow Sediment transport

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Effects of vegetation on flow conveyance and sediment transport capacity

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International Journal of Sediment Research 2009年第3期24卷 247-259页

作者： Weiming WU1 and Zhiguo HE21 Research assoc. prof., National Center for Computational Hydr.science and Engineering, University of Mississippi, University, MS 38677, USA, 2 Postdoctoral Research assoc., National Center for Computational Hydr.science and Engineering, University of Mississippi, University, MS 38677, USA.Present at Department of Hydr.ulic and Ocean Engineering, Zhejiang University, Hangzhou 310058, China, Research assoc. prof. National Center for Computational Hydroscience and Engineering University of Mississippi University MS 38677 USA Postdoctoral Research assoc. National Center for Computational Hydroscience and Engineering University of Mississippi University MS 38677 USA

In-stream and riparian vegetation may significantly affect flow and sediment transport in vegetated channels. A hydr.ulic model has been developed in this paper to compute the flow discharge in channels with rigid and flexible vegetation under emergent and submerged conditions. An empirical formula has also been presented to determine the bed-load discharge in vegetated channels. The model has been tested against experimental and field data available in the literature. The computed flow discharge and bed-load transport rate agree well with the measured data.

关键词： Vegetation Flow resistance Sediment transport Bed load

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Turbulence,suspension and downstream fining over a sand-gravel mixture bed

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International Journal of Sediment Research 2013年第2期28卷 194-209页

作者： K.GHOSHAL Rahul MAZUMDER C.CHAKRABORTY B.S.MAZUMDER Department of Mathematics Indian Institute of TechnologyKharagpur 721302India Assist.Prof. MIT CambridgeUSA Post-Doctoral Assoc. Fluvial Mechanics Laboratory Physics and Earth Science DivisionIndian Statistical InstituteKolkata 700108India Prof.

Flume experiments were carried out to study the turbulence and its impact on suspension and segregation of grainsizes under unidirectional flow conditions over the sand-gravel mixture *** components of fluid velocity with fluctuations were measured vertically using 3-D Micro-acoustic Doppler velocimeter(ADV).The theoretical models for velocity and sediment suspension have been developed based on the concept of mixing length that includes the damping effect of turbulence due to sediment suspension in the flow over the sand-gravel mixture *** analysis of segregation of grain-sizes along downstream of the bed has been performed using the principle of unsupervised learning or clustering *** data analysis suggests that there is a progressive downstream fining of sediment sizes with selective depositions of gravels,sand-gravels and sand materials along the stream,which may be segmented into three regions such as,the upstream,the transitional and the downstream *** contribution is relevant to understand the direction of ancient rivers,the bed material character in the river form,sorting process and its role in controlling the sediment flux through landscape.

关键词： Sand-gravel mixture Flow velocity ADV Suspension concentration Size-sorting Clustering

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Modified vegetation-erosion dynamics model and its application in typical watersheds in the Loess Plateau

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International Journal of Sediment Research 2011年第1期26卷 78-86页

作者： CHEN Yuehong~1,WANG Feixin~2,LIU Guangquan~3,YU Xinxiao~4, JIA Guodong~5,and GAN Ping~6 China Institute of Water Resources and Hydr.power Research,Beijing 100048 International Research and Training Center on Erosion and Sediment Research,Beijing 100048,China Beijing Forestry University,Beijing 100083,China. Key Lab of dr.dging Technology of CCGRP,Shanghai Waterway Engineering Design and Consulting Co., Ltd,Shanghai 200120,China. International Research and Training Center on Erosion and Sedimentation China Institute of Water Resources and Hydr.power Research,Beijing 100048 Northwest A&F University,Yangling 712100,China, Beijing Forestry University,Beijing 100083,China, Beijing Forestry University,Beijing 100083,China. China Institute of Water Resources and Hydr.power Research,Beijing 100048,and International Research and Training Center on Erosion and Sediment Research,Beijing 100048,China assoc. prof. Dr. China Institute of Water Resources and Hydropower Research Beijing 100048 International Research and Training Center on Erosion and Sediment Research Beijing 100048 China Beijing Forestry University Beijing 100083 China dr. Key Lab of Dredging Technology of CCGRP Shanghai Waterway Engineering Design and Consulting Co. Ltd Shanghai 200120 China prof. Dr. International Research and Training Center on Erosion and Sedimentation China Institute of Water Resources and Hydr.power Research Beijing 100048 Northwest A&F University Yangling 712100 China prof. Dr. Beijing Forestry University Beijing 100083 China dr. Beijing Forestry University Beijing 100083 China Engineer China Institute of Water Resources and Hydropower Research Beijing 100048 and International Research and Training Center on Erosion and Sediment Research Beijing 100048 China

The vegetation-erosion model was applied in three typical watersheds of hilly and gully area in the Loess Plateau in northwestern China to study the dynamic relations between vegetation coverage and soil erosion rate and various *** model was improved by introducing rainfall and runoff *** the modified model was applied in the Luergou and Luoyugou *** calculation results with the modified model were compared with the results of the original *** precisions of simulated vegetation coverage and soil erosion rate with the modified model were greatly improved compared with the original *** erosion rate reduced with increasing vegetation coverage and the human disturbance caused high soil erosion.

关键词： Soil erosion Vegetation coverage Vegetation-erosion dynamics model Loess Plateau Modified model

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Characteristics of energy dissipation in hyperconcentrated flows

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International Journal of Sediment Research 2008年第4期23卷 387-397页

作者： An-ping SHU 1,Qing-quan LIU2,Yu-jun YI 3,and Zhi-dong ZHANG 41 assoc.prof.,School of Environment,Key Laboratory of Water and Sediment Sciences of Ministry of Education,Beijing Normal University,Beijing 100875,China2 prof.,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100080,China3 Lecturer,dr.,School of Environment,Beijing Normal University,Beijing 100875,China4 Graduate student,School of Environment,Beijing Normal University,Beijing 100875,China assoc. prof. School of Environment Key Laboratory of Water and Sediment Sciences of Ministry of Education Beijing Normal University Beijing 100875 China prof. Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Lecturer Dr. School of Environment Beijing Normal University Beijing 100875 China. The project is supported by the National Natural Science Foundation of China (Grant No. 10672024) Graduate student School of Environment Beijing Normal University Beijing 100875 China

An equilibrium equation for the turbulence energy in sediment-laden flows was derived on the basis of solid–liquid two-phase flow theory. The equation was simplified for two-dimensional, uniform, steady and fully developed turbulent hyperconcentrated flows. An energy efficiency coefficient of suspended-load motion was obtained from the turbulence energy equation, which is defined as the ratio of the sediment suspension energy to the turbulence energy of the sediment-laden flows. Laboratory experiments were conducted to investigate the characteristics of energy dissipation in hyperconcentrated flows. A total of 115 experimental runs were carried out, comprising 70 runs with natural sediments and 45 runs with cinder powder. Effects of sediment concentration on sediment suspension energy and flow resistance were analyzed and the relation between the energy efficiency coefficient of suspended-load motion and sediment concentration was established on the basis of experimental data. Furthermore, the characteristics of energy dissipation in hyperconcentrated flows were identified and described. It was found that the high sediment concentration does not increase the energy dissipation; on the contrary, it decreases flow resistance.

关键词： Hyperconcentrated flows Turbulence energy Efficiency coefficient Energy dissipation

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Temporal variation of suspended sediment load in the Pearl River due to human activities

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International Journal of Sediment Research 2011年第4期26卷 487-497页

作者： Wei ZHANG,Shousheng MU,Yanjing ZHANG,and Kaimin CHEN 1 assoc.prof.,State Key Laboratory of Hydr.logy-Water Resources and Hydr.ulic Engineering,Hohai University, Nanjing,210098,China, 2,4 Graduate student,College of Harbor,Coastal and Offshore Engineering,Hohai University,Nanjing,210098, China 3 prof.,China Institute of Water Resources and Hydr.power Research,Beijing,100038,China assoc. prof. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China Graduate student College of Harbor Coastal and Offshore Engineering Hohai University Nanjing 210098 China prof. China Institute of Water Resources and Hydropower Research Beijing 100038 China

Data on sediment flux at three hydr.logic stations from the 1950s to 2006 are utilized to study the decadal,annual,and monthly variations in suspended sediment load delivered from the Pearl River to the *** show that variations in sediment flux from three main tributaries,including the West River,the North River and the East River,are spatially *** nearly 90%of the suspended sediment load comes from the West River,its variation has dominated the overall tendency of sediment flux in the entire Pearl *** a significant decreasing trend exists in the annual variation of the total sediment flux,the decadal change can be divided into an increasing phase and a decreasing phase,with the turning point between the two phases in the late *** the 1950s to the 1980s,the average annual river sediment flux increased by 30.43%.However,sediment flux has decreased significantly since the 1990s,with the average sediment flux being 38.60%less in the 2000s than that in the *** current sediment flux is also 52.93%less than its peak in the 1980s. The monthly variation pattern of the suspended sediment load transport to the sea is more interesting. For the West River,all months show a decreasing trend,and for most months the reduction values are ***,for the East River the sediment load shows a decrease trend in the dr. season and an increase trend in the wet *** method of regression analysis was used to study the influence of precipitation in the variation on the sediment *** was found that the climate change is not the main dr.ving force behind the variation in suspended sediment *** the 1990s, intensive land use destroyed the vulnerable ecosystem of the upper Pearl River,and speeded up the process of rocky ***,aggravated soil erosion caused an increase in suspended sediment ***,sediment retention within reservoirs had begun to play a dominant role after the massive constru

关键词： Pearl River Sediment flux Human activities Rocky desertification Dam construction

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A process-based model for sediment transport under various wave and current conditions

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International Journal of Sediment Research 2011年第4期26卷 498-512页

作者： Chi ZHANG,Jin-Hai ZHENG,Yi-Gang WANG, Meng-Tao ZHANG,Dong-Sheng JENG,and Ji-Sheng ZHANG 1 dr.,State Key Laboratory of Hydr.logy-Water Resources and Hydr.ulic Engineering,Hohai University,1 Xikang Road,Nanjing 210098,China, 2 prof.Corresponding author,State Key Laboratory of Hydr.logy-Water Resources and Hydr.ulic Engineering, Hohai University,1 Xikang Road,Nanjing 210098,China, 3 prof.,4 Bachelor,6 assoc.prof.,College of Harbor,Coastal and Offshore Engineering,Hohai University,1 Xikang Road,Nanjing 210098,China 5 prof.Center for Marine Geotechnical Engineering Research,Shanghai Jiao Tong University,Shanghai 200240, China Division of Civil Engineering,University of Dundee,Dundee DD1 4HN,United Kingdom dr. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University 1 Xikang Road Nanjing 210098 China prof. Corresponding author State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University 1 Xikang Road Nanjing 210098 China prof. College of Harbor Coastal and Offshore Engineering Hohai University 1 Xikang Road Nanjing 210098 China Bachelor College of Harbor Coastal and Offshore Engineering Hohai University 1 Xikang Road Nanjing 210098 China prof. Center for Marine Geotechnical Engineering Research Shanghai Jiao Tong University Shanghai 200240 China Division of Civil Engineering University of Dundee Dundee DD1 4HN United Kingdom assoc. prof. College of Harbor Coastal and Offshore Engineering Hohai University 1 Xikang Road Nanjing 210098 China

The purpose of this study is to investigate the capability of a newly developed process-based model for sediment transport under a wide variety of wave and current *** model is based on the first-order boundary layer equation and the sediment advection-diffusion *** particular,a modified low Reynolds number k-e model is coupled to provide the turbulence *** model verifications have been performed by simulating a number of laboratory experiments,covering a considerable range of hydr.dynamic conditions such as sinusoidal waves,asymmetric waves and wave-current *** model provides satisfactory numerical results which agree well with the measured results,including the time-averaged/dependent sediment concentration prof.les and sediment flux prof.les,as well as the time series of concentration at given *** observed influences of wave orbital velocity amplitude,wave period and sediment grain size are correctly reproduced,indicating that the fundamental physical mechanisms of those processes are properly represented in the *** is revealed that the present model is capable of predicting sediment transport under a wide range of wave and current conditions,and can be used to further study the morphodynamic processes in real coastal regions.

关键词： Sediment transport Wave Current Numerical model

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LIVE-BED SCOUR IN LONG CONTRACTIONS

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International Journal of Sediment Research 2006年第2期21卷 166-170页

作者： Subhasish DEY Rajkumar V. RAIKAR Department of Civil Engineering Indian Institute of Technology Kharagpur 721302 West Bengal India Assoc. Prof. Department of Civil Engineering Indian Institute of Technology Kharagpur 721302 West Bengal India Dr.

This paper presents a simple analytical model, developed using the energy and continuity equations, for the computation of the live-bed scour depth in long contractions. The model agrees satisfactorily with experimental data. Equations previously proposed in the literature for estimation of the equilibrium scour depth in long contractions are compared with experimental data. The comparison indicates that the equation given by Lim is the best predictor among those examined.

关键词： Open channel flow Steady flow Channel contraction Channel erosion Scour Erosion Sediment transport Hydr.ulics

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The Antibacterial Effect of Silver-carrying B_2O_3-SiO_2-Na_2O Glass Material

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Journal of Wuhan University of Technology(Materials Science) 2005年第2期20卷 105-108页

作者：徐瑛 School of Science Wuhan University of TechnologyWuhan 430070China Assoc.Prof

The antibacterial effect of carrying silver B_2O_3-SiO_2-Na_2O glass material was studied by means of antibacterial ring, nephelometery,MIC value, thin film attachment and microcalorimetry, respectively. The experimental results of five kinds of antibacterial test methods are almost identical and can verify that carrying silver B_2O_3-SiO_2-Na_2O glass material exerts an excellent antibacterial performance. Antibacterial ring and nephelometery are simple, quick, but the precision is restrictive. MIC value, thin film attachment method and microcalorimetry can quantitatively compare the antibacterial effects of the antibacterial glass *** with the traditional microbe test methods, the microcalorimetry can analyze the inhibiting effect of the cell's growth and metabolism on the antibacterial glass material by monitoring the thermal effect continuously and automatically.

关键词： antibacterial glass material silver antibacterial effect

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