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Establishment of a Sediment transport capacity equation on loessal slope via experimental investigation

International Journal of sediment Research 2023年第2期38卷 166-174页

作者： Tian Wang Jingsi Li Jingming Hou Peng Li Shengdong Cheng Feng Wang Wen Wang Zhanbin Li Reinhard Hinkelmann State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China Xi'an University of Technology Chair of Water Resources Management and Modeling of Hydrosystems Department of Civil Engineering Technische Universit at Berlin Shaanxi Province Institute of Water Resources and Electric Power Investigation and Design Key Laboratory of National Forestry Administration on Ecological Hydrology and Disaster Prevention in Arid Regions Xi'an University of Technology

Areliable Sediment transport capacity function provides response against challenges of soil erosion prediction on the Loess Plateau of China. The popular Sediment transport capacity functions are questionable on loess slopes because the experimental conditions from which they were derived, like bed materials, gentle slopes,and surface roughness, are different from soil erosion processes on the loess slopes. Due to the foregoing uncertainty, a suitable Sediment transport capacity function was developed based on a flume experiment investigation. The erodible bed experiment was implemented for five unit width discharges(1.3 × 10-4-3.3 × 10-4m2/s) and ten slopes(5.2%-57.7%). The selected Sediment transport capacity equations were tested in an applicability evaluation. The results of this evaluation found that the Govers(1990) function had the best performance(P.O.0.5-2.0= 76%, R2= 0.93, RMSE = 0.03 kg/(m·s)), followed by the Yalin(1963) function(P.O.0.5-2.0= 80%, R2= 0.81, RMSE = 0.05 kg/(m·s)), and finally by the Low(1989) function(P.O.0.5-2.0= 72%,R2= 0.79, RMSE = 0.04 kg/(m·s)), where P.O.0.5-2.0is the percentage of estimated values with logarithmic discrepancies with the measured value between 0.5 and 2.0; R2is the coefficient of determination and RMSE is the roof mean squares error. The cohesive sediment incipient motion velocity is introduced into the Govers(1990) function, and the sediment particle parameter is determined from measured experimental data. The developed Sediment transport capacity equation has good performance with predicted values corresponding to measured values(P.O.0.5-2.0= 98%, R2= 0.98, RMSE = 0.006 kg/(m·s)). The research results provide an improved Sediment transport capacity function on the basis of experiments for steep loessal slopes.

关键词： Experimental investigation Hydraulic conditions Loessal slope Sediment transport capacity

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Effects of sediment characteristics on the Sediment transport capacity of overland flow

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International Soil and Water Conservation Research 2023年第1期11卷 75-85页

作者： Chenguang Liu Suhua Fu Zhanbin Li Zeyu Zhang Jianhui Zeng Institute of Soil and Water Conservation Northwest A&F UniversityYanglingShaanxi712100PR China State Key Laboratory of SoilErosion and Dryland Farming on the Loess Plateau Institute of Soil and Water ConservationChinese Academy of Sciences and Ministry of Water ResourceYanglingShaanxi712100PR China Beijing Key Laboratory of Environmental Remote Sensing and Digital City Faculty of Geographical ScienceBejing Normal UniversityBejing100875PR China

The transport of sediments is a crucial part of soil erosion.Accurately calculating the Sediment transport capacity is key to the construction of soil erosion process models.Research on Tc has focused mainly on the dynamics of a single particle of sediment and hydraulic variables.There have been few studies of the impact of soil aggregates on the Tc.To clarify how sediment characteristics,including those for single particles and aggregates,affect the Tc of overland flow with no raindrop import,flume experiments were implemented at slope gradients varying from 5.24%to 26.80%and flow discharges ranging from 0.68 to 5.41×10^(-3)m^(2)s^(-1).The experimental materials were five typical soils in China.The results indicated that the correlation between the measured Tc and sediment mechanical composition indexes of the five soils was indistinctive in this study.The sediment settling velocity with aggregates has a significant corre-lation with the measured Tc.New equations,including for the sediment settling velocity with aggregatesωud75,were established to calculate the Tc.The empirical equation that includedωud75,slope gradient and unit discharge performed greatly in predicting Tc(R^(2)=0.93,NSE=0.90).ωud75 can effectively improve the calculation accuracy of Tc.The new equation including flow and sediment properties obtained through dimensional analysis performed well in predicting Tc(R^(2)=0.99,NSE=0.91),and the calculation accuracy was better than that of the empirical model derived in this study.These findings indicate that the sediment settling velocity is an important variable in the equation for predicting Sediment transport capacity of overland flow.

关键词： Sediment transport capacity Soil mechanical composition Soil aggregates sediment settling velocity Dimensional analysis

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SUSPENDED Sediment transport capacity OF OPEN CHANNEL FLOW

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International Journal of sediment Research 1997年第3期 1-10页

作者： Zhixian Cao Prot. Dr.-Ing.. Director of Institute of Hydraulic Engineering, Tianjin University. Tianjin 300072. China. Wensheng WangSenior Engineer, Associate Director of Lower Haihe River Administration Bureau. Ministry of Water Resources. Tianjin 300061

A turbulent bursting-based formulation for suspended Sediment transport capacity is verified with data from Brownlie (1981). Previous formulations are examined using the results of data analysis. Satisfactory performance of the turbulent bursting-based formulation is demonstrated, in addition to its strong physical background. Einstein’s formula is found to over-or under-estimate Sediment transport capacity in some cases. Celik and Rodi’s correlation is shown to behave poorly. The WUHEE curve does not fit the measured data well. Further, the transport capacity is exhibited to increase nonlinearly with the nondimensional quantity u3 /ghw. This behavior upsets many existing formulas, in which the transport capacity is represented as linear functions of U3 /ghw. It is suggested that existing formulations be used cautiously, and more wellgrounded developments based on turbulent bursting be pursued.

关键词： Sediment transport capacity sediment entrainment near-bed sediment concentration turbulent bursting sediment transport open channel flow

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由规定变窄更低的黄河能导致搜索的 non-siltation 甚至隧道吗？

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Journal of Geographical Sciences 2016年第9期26卷 1337-1348页

作者： SUN Zanying WANG Wanzhan LI Yong ZHANG Mingwu SHANG Hongxia ZHANG Fangxiu Yellow River Institute of Hydraulic Research Zhengzhou 450003 China

This study considered whether the narrowing of the upper （broad and wandering） reaches of the Lower Yellow River could result in a reduction in sedimentation and even an increase in channel erosion in both the upper and the lower （narrow and meandering） reaches. Analysis of field data and numerical modeling results both justify the proposal to narrow the channel. A positive correlation was found between channel eroded-area and the channel width. Therefore narrowing under conditions of low flow will reduce the amount of erosion in the reach, which, in turn, will reduce the amount of sediment transported into the lower channel. This will reduce the amount of siltation in the lower reaches of the river. However, narrowing under conditions of high flow with a low concentration of sediment will reduce both the extent of flood attenuation along the narrowed channel and the amount of lateral channel bank collapse, which results in increased flows and less sedimentation in the lower channel, leading to increased erosion. When flows with a high concentration of sediment are released from the Xiaolangdi Reservoir, both the lower narrow channel and the upper channel can transport a large amount of the sediment load. It is concluded that the narrowing of the upper broad channel will result in a reduction in sedimentation, or even in channel erosion, in both the upper and the lower channels if the reservoir is operated such that the volume of sediment added during low flows is balanced by the volume eroded during high flows with a low concentration of sediment.

关键词： channel narrowing sediment release Sediment transport capacity Lower Yellow River, XiaolangdiReservoir

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One-dimensional numerical simulation of non-uniform sediment transport under unsteady flows

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International Journal of sediment Research 2008年第4期23卷 316-328页

作者： Hongwei FANG 1,Minghong CHEN 2,and Qianhai CHEN 31 Prof.,Dept.of Hydraulic Engineering,Tsinghua Univ.,State Key Laboratory of Hydroscience and Engineering,Beijing,100084,China 2 PhD,College of Water Conservancy and Civil Engineering,China Agricultural Univ.,Beijing 100083,China.3 Engineer,Institute of the Yangtze River Research,Wuhan,430010,China Prof. Dept. of Hydraulic Engineering Tsinghua Univ. State Key Laboratory of Hydroscience and Engineering Beijing 100084 China PhD College of Water Conservancy and Civil Engineering China Agricultural Univ. Beijing 100083 China Engineer Institute of the Yangtze River Research Wuhan 430010 China

One-dimensional numerical models are popularly used in sediment transport research because they can be easily programmed and cost less time compared with two-and three-dimensional numerical models.In particular,they possess greater capacity to be applied in large river basins with many tributaries.This paper presents a one-dimensional numerical model capable of calculating total-load sediment transport.The cross-section-averaged Sediment transport capacity and recovery coefficient are addressed in the suspended load model.This one-dimensional model,therefore,can be applied to fine suspended loads and to hyperconcentrated flows in the Yellow River.Moreover,a new discretization scheme for the equation of unsteady non-uniform suspended sediment transport is proposed.The model is calibrated using data measured from the Yantan Reservoir on the Hongshui River and the Sanmenxia Reservoir on the Yellow River.A comparison of the calculated water level and river bed deformation with field measurements shows that the improved numerical model is capable of predicting flow,sediment transport,bed changes,and bed-material sorting in various situations,with reasonable accuracy and reliability.

关键词： One-dimensional numerical model Sediment transport capacity Recovery coefficient Adaptation length Unsteady flow

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