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Sediment removal efficiency of siphon dredging with wedge-type suction head and float tank

International Journal of Sediment Research 2010年第2期25卷 149-160页

作者： su-chin chen Chun-Hung WU Department of Soil and Water Conservation National Chung Hsing University

Siphon dredging with a float tank and different siphon suction heads, including the plain-type and wedge-type with/without side holes, through flume experiments were used to investigate the reservoir sediment removal efficiency. The experiment revealed maximum suction pressure and velocity when the distance from the suction head to the bed was about 25% of suction head diameter. suction pressure decreased rapidly as the distance from the suction head to the bed increased to 50% and 100% of suction head diameter. suction pressure achieved by wedge-type suction head was only 16.9-17.6% of that around plain-type suction head, and the velocity around wedge-type suction head was 64.7-68.4% of that around plain-type suction head. However the plain-type suction head was easily clogged doe to its long bobbing period. The average bobbing period for the plain-type suction head was about 105-263% that of the wedge-type suction head. The sediment removal efficiency was achieved when float tank diameter was 3-4 times that of the suction head. Flow discharge and sediment removal increased as the suction head diameter and side hole diameter increased, respectively. The most efficient side hole area was an area within 15% of suction head area. Totally, the optimal sediment removal efficiency was the wedge angle of 20° with 3 side holes. The efficiency of sediment dredging by siphon suction with a suction tube passing through the dam bottom was better than that with suction passing over the top of the dam. The wedge-type siphon suction with a float tank is preferable for sediment dredging in small reservoirs because it is inexpensive and efficient.

关键词： Siphon dredging Sediment removal Wedge-type suction head Side hole Float tank

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Large-Scale Desiccation of the Aral Sea due to Over-Exploitation after 1960

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Journal of Mountain Science 2012年第4期9卷 538-546页

作者： Behzod GAYBULLAEV su-chin chen Yi-Ming KUO Department of Soil and Water Conservation Taiwan Chung Hsing University No.25o Kuo-Kuang Rd. South District 40227 Taichung Chinese Taipei Department of Design for sustainable Environment Ming Dao University No.369 Wen-Hua Rd. Peetow 52345 Changhua Chinese Taipei

The Aral Sea was one of the largest lakes in the world before it started to shrink in the 1960s due to water withdrawal for agricultural irrigation. Precipitation decreased from 9.4 kmin 1960 to 3.2 km3 in 2009, and annual river inflow into the Aral Sea decreased from 31.5 km3 in 1998 to 5.2 km3 in 2009. Comparison on the hydrological data of the Aral Sea between 1960 and 2009 showed the evaporation, water surface area, and water volume decreased by 90%, 80%, and 88%, respectively. This study employs the observed values of water volume, precipitation, runoff, evaporation, and salinity to estimate water volume and salinity from 1960 to 2009, and the efficiency coefficients for predicted water volume and salinity are o.975 and 0.974, respectively. Regression equations calculated from the observed data are used to predict precipitation, runoff, evaporation, and salinity from 20lO to 2021, and the results are then applied in the estimation of water volume and salinity Our estimates suggest that salinity will increase to around 200 g/L and water volume will decrease to around 83 km3 in 2021.

关键词： Aral Sea Irrigation Water volume Salinity Evaporation

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Dimension and frequency of bar formation in a braided river

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International Journal of Sediment Research 2013年第3期28卷 358-367页

作者： Hsuan-pei AN su-chin chen Hsun-chuan CHAN Yi Hsu Department of Soil and Water Conservation National ChungHsing University

This paper presents flume and field observations of a bank-confined braided *** features,including plan form configuration,channel width,and main channel migration,were examined by a series of *** measurements of channel morphology,provided a basis to estimate the relationship between noncumulative frequency of bars and bar *** results from the Dajia River,located in Central Western Taiwan,were presented to provide a reference data set for comparing the laboratory and field *** results indicate that the relationship between bar length and width can be predicted by a simple best-fit power function relating to self-similarity *** Hurst index by Walsh and Hicks(2002) provides acceptable predictions of the bar length and width observed in the experiments and confirmed by the field *** and field results both show that large river width yields a uniform distribution of bar areas with the similar discharge,leading to a large value of exponent(ft) in the *** river width is confirmed to be a critical parameter in the main channel shift.A small increase in channel width likely increased rapidly the shift cycle.

关键词： Braided river Bank confinement Bar morphology

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Effects of submerged flexible vegetation and solid structure bars on channel bed scour

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International Journal of Sediment Research 2012年第3期27卷 323-334+336+335页

作者： su-chin chen Yi-ming KUO Hsiao-chia YEN Dept.of Soil and Water Conservation National Chung Hsing Univ. Dept.of Design for sustainable Environment Ming Dao Univ. Soil and Water Conservation Bureau Council of Agriculture

The effects of different submerged obstacle longitudinal bars with different arrangement densities on the flow profile and morphology of a scour hole were investigated under clear water conditions. Acoustic Doppler velocimetry(ADV) data were applied to plot the vertical distributions of three-dimensional velocities and turbulent *** experimental results indicate that arrangement density(also can represent porosity),structural material(flexible or solid),and the sidewall effect are the main factors impacting turbulent kinetic energy and the morphology of scour *** flexible vegetation,the maximum turbulent kinetic energy near the bed surface increased with the arrangement *** the same structure,the depth and the magnitude of the lateral expansion of the scour hole also increased with the arrangement *** flexible vegetation reduced the depth of the scour hole because of deflection and arrangement *** larger volumes of scour found in the upstream and middle sections of solid structures compare well to those in flexible *** deflection of porous flexible vegetation transported the turbulent kinetic energy downstream,reduced the turbulent kinetic energy near the sediment bed,and increased the stability of the *** vegetation bars are able to protect the bank and the bed of a river under normal conditions,making them a good alternative design in the management and restoration of rivers.

关键词： Flexible vegetation Solid structure Local scour Longitudinal bar Turbulent kinetic energy

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Bedform development and its effect on bed stabilization and sediment transport based on a flume experiment with non-uniform sediment

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International Journal of Sediment Research 2017年第3期32卷 305-312页

作者： su-chin chen Chia-Ning Yang ching-Ying Tsou Department of Soil and Water Conservation National Chung Hsing University Sinotech Engineering Consultants LTD. Department of Agricultural and Environmental Engineering Faculty of Agriculture and Life Science Hirosaki University

Non-uniform sediment deposited in a confined, steep mountain channel can alter the bed surface composition. This study evaluates the contribution of geometric and resistance parameters to bed stabilization and the reduction in sediment transport. Flume experiments were done under various hydraulic conditions with non-uniform bed material and no sediment supply from upstream. Results indicate that flume channels respond in a sequence of coarsening and with the formation of bedformroughness features such as rapids, cascades, and steps. A bedform development coefficient is introduced and is shown to increase(i.e. vertical sinuosity develops) in response to increasing shear stress during the organization process. The bedform development coefficient also is positively correlated with the critical Shields number and Manning’s roughness coefficient, suggesting the evolution of flow resistance with increasing bedform development. The sediment transport rate decreases with increasing bed shear stress and bedform development, further illustrating the effect of bed stabilization. An empirical sediment transport model for an equilibrium condition is proposed that uses the bedform development coefficient, relative particle submergence(i.e. the ratio of mean water depth and maximum sediment diameter), modified bed slope, and discharge. The model suggests bedform development can play a primary role in reducing sediment transport(increasing bed stabilization). The model is an extension of Lane’s(1955) relation specifically adapted for mountain streams. These results explain the significance of bedform development in heightening flow resistance, stabilizing the bed, and reducing sediment transport in coarse, steep channels.

关键词： Bedform development Bed stabilization Sediment transport Non-uniform bed

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Long-Term Impact of Extra Sediment on Notches and Incised Meanders in the Hoshe River, Taiwan

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Journal of Mountain Science 2013年第5期10卷 716-723页

作者： su-chin chen Chun-Hung WU Yi-Chiung CHAO Pei-Yu SHIH Dept. of Soil and Water Conservation National Chung Hsing University Water Resources Engineering and Conservation Feng Chia University

The extra sediment load induced by typhoons and rainstorms in the Heshe River, Taiwan, are the principal reason for severe sediment-related disasters. The total sediment load during Typhoon Morakot in 9009 was 31 x lo6 m3, accounting for 95% of the annual sediment discharge. Large amounts of sediment load entered the Hoshe River, causing the braiding index （BI） to increase. subsequently, the BI became positively correlated with the channel width in the Hoshe River. The specific typhoon and rainstorm events decreased after Typhoon Morakot, the sediment input decreased, inducing the fluvial morphology of the braided river to develop into a meandering river. The extra sediment load induced the deposition depth to increase and produce a headward deposition in the main channel and its tributaries. In addition, the river bend and the topographical notch restrained the sediment from moving downstream and being stored locally, indirectly increasing the erosion density of the river banks from 2.5 to lo.5 times.

关键词： Extra sediment load River morphology Braiding index

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RESERVOIR SEDIMENTATION AND LAND USE IN TAIWAN WUSHEH WATERSHED

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International Journal of Sediment Research 1998年第3期 35-43页

作者： su chin chen 1

ＲＥＳＥＲＶＯＩＲＳＥＤＩＭＥＮＴＡＴＩＯＮＡＮＤＬＡＮＤＵＳＥＩＮＴＡＩＷＡＮＷＵＳＨＥＨＷＡＴＥＲＳＨＥＤＳｕＣｈｉｎＣＨＥＮ１ＡＢＳＴＲＡＣＴＷｕｓｈｅｈＲｅｓｅｒｖｏｉｒｉｓａｇｏｒｇｅｔｙｐｅｈｙｄｒｏ... 详细信息

ＲＥＳＥＲＶＯＩＲＳＥＤＩＭＥＮＴＡＴＩＯＮＡＮＤＬＡＮＤＵＳＥＩＮＴＡＩＷＡＮＷＵＳＨＥＨＷＡＴＥＲＳＨＥＤＳｕＣｈｉｎＣＨＥＮ１ＡＢＳＴＲＡＣＴＷｕｓｈｅｈＲｅｓｅｒｖｏｉｒｉｓａｇｏｒｇｅｔｙｐｅｈｙｄｒｏｐｏｗｅｒＲｅｓｅｒｖｏｉｒｏｎＷ...

关键词： Wusheh Reservoir Land use Sedimentation

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RETROGRESSIVE EROSION AND LONGITUDINAL PROFILE EVOLUTION IN NONCOHESIVE MATERIAL

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International Journal of Sediment Research 2006年第2期21卷 113-122页

作者： Lien-Kuang chen su-chin chen Department of Soil and Water Conservation National Chung Hsing University Taichung Taiwan 402 China Dr. Department of Soil and Water Conservation National Chung Hsing University Taichung Taiwan 402 China Prof.

Retrogressive erosion plays a significant role in soil erosion and in channel morphology evolution. Retrogressive erosion occurs and migrates when the flow conditions and/or channel bed slope change. This study investigates through a series of experiments, the migration behavior of retrogressive erosion and the longitudinal profile evolution of a channel consisting of noncohesive sediment. Experimental results indicate that retrogressive erosion can be categorized into two types, stepped and rotating. In stepped erosion a nearly parallel erosion surface migrates upstream at a constant speed. The migration speed in rotating erosion is a function of the square root of time. The experimental results reveal that the discharge does not affect the migration speed of stepped erosion. However, the migration speed of rotating erosion increases with rising discharge. The crucial difference between rotating and stepped erosion, i.e. the threshold value separating the two forms of erosion is a function of the initial channel bed lowering and critical water depth. A model of retrogressive erosion in a noncohessive channel is developed based on the experimental results.

关键词： Headcuts Retrogressive erosion Knickpoint Stepped and rotating

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MODELING THE FATE AND TRANSPORT OF HYDROPHOBIC ORGANIC COMPOUNDS IN AN UNSTEADY RIVER-ESTUARINE SYSTEM

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International Journal of Sediment Research 2002年第3期17卷 197-210页

作者： su-chin chen,Jan-Tai KUO Professor Department of Soil and Water Conservation National Chung-Hsing University Taichung 402 Taiwan china Professor Department of Civil Engineering National Taiwan University Taipei 106 Taiwan china

This research develops a generalized, one-dimensional, finite difference model for simulating the distribution of toxic substances in a river-estuarine system. The three sub-models for unsteady flow, sediment transport, and the reaction of toxic substances are also presented using an uncoupled numerical method. The paper also includes experimental work for sorption/desorption, field measurements of organic carbon content in the heavily polluted Keelung River, and a laboratory study of cohesive sediment transport for the model calibration and verification. In addition, this study simulates the polycyclic aromatic hydrocarbons (PAHs) in the Keelung River in northern Taiwan as a case study. Encouraging results are obtained, and suggest that the modeling approach could be extended to simulate the fate and transport of sorbed pollutants in tidal river.

关键词： Toxic substance model Tidal flow Sediment transport Sorption and desorption kinetics Polycyclic Aromatic Hydrocarbons (PAHs) Keelung River

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Deep eutectic solvents for separation and purification applications in critical metal metallurgy:Recent advances and perspectives

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 1-19页

作者： Shuo chen Shengpeng su Yanfang Huang Bingbing Liu Hu sun Shuzhen Yang Guihong Han School of Chemical Engineering Zhengzhou UniversityZhengzhou 450001China Zhongyuan Critical Metals Laboratory Henan ProvinceZhengzhou 450001China

Solvent extraction,a separation and purification technology,is crucial in critical metal *** solvents commonly used in solvent extraction exhibit disadvantages,such as high volatility,high toxicity,and flammability,causing a spectrum of hazards to human health and environmental *** solvents have been recognized as potential alternatives to these harmful organic *** the past two decades,several neoteric solvents have been proposed,including ionic liquids(ILs)and deep eutectic solvents(DESs).DESs have gradually become the focus of green solvents owing to several advantages,namely,low toxicity,degradability,and low *** this critical review,their classification,formation mechanisms,preparation methods,characterization technologies,and special physicochemical properties based on the most recent advancements in research have been systematically ***,the major separation and purification applications of DESs in critical metal metallurgy were comprehensively ***,future opportunities and challenges of DESs were explored in the current research *** conclusion,this review provides valuable insights for improving our overall understanding of DESs,and it holds important potential for expanding separation and purification applications in critical metal metallurgy.

关键词： deep eutectic solvents preparations properties separation and purification critical metal metallurgy

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