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Modelling of meander migration in an incised channel

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International Journal of Sediment Research 2014年第4期29卷 441-453页

作者： Jianchun HUANG Blair P.GREIMANN Timothy J.RANDLE Hydraulic Engineers Sedimentation and River Hydraulics GroupTechnical Service CenterBureau of Reclamation

An updated linear computer model for meandering rivers with incision has been *** model simulates the bed topography,flow field,and bank erosion rate in an incised meandering *** a scenario where the upstream sediment load decreases(e.g.,after dam closure or soil conservation),alluvial river experiences cross section deepening and slope *** channel migration rate might be affected in two ways:decreased channel slope and steeped bank *** proposed numerical model combines the traditional one-dimensional(1D) sediment transport model in simulating the channel erosion and the linear model for channel meandering.A non-equilibrium sediment transport model is used to update the channel bed elevation and gradations.A linear meandering model was used to calculate the channel alignment and bank erosion/accretion,which in turn was used by the 1D sediment transport *** the 1D sediment transport model,the channel bed elevation and gradations are representedin each channel cross *** the meandering model,the bed elevation and gradations are stored in two dimensional(2D) cells to represent the channel and terrain properties(elevation and gradation).A new method is proposed to exchange information regarding bed elevations and bed material fractions between 1D river geometry and 2D channel and *** ability of the model is demonstrated using the simulation of the laboratory channel migration of Friedkin in which channel incision occurs at the upstream end.

关键词： Numerical model River channel migration Meandering river Linearization analysis Sediment transport

Morphodynamic Characteristics and Medium-Term Simulation of the North-South Passage Under the Impact of the Yangtze Estuary Deepwater Navigation channel Project

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China Ocean Engineering 2020年第2期34卷 198-209页

作者： JIAO Jian DOU Xi-ping GAO Xiang-yu DING Lei YANG Xiao-yu Key Laboratory of Port Waterway and Sedimentation Engineering of MOTNanjing Hydraulic Research InstituteNanjing 210029China College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China

The morphological evolution characteristics of the North-South Passage area since the construction of the Yangtze Estuary Deepwater Navigation channel Project(DNCP)are analyzed on the basis of the measured data.A twodimensional morphodynamics numerical model of the Yangtze Estuary is established to verify the morphological evolution of the North-South Passage under the influence of the DNCP and to predict the future evolution in the next 40 *** analysis shows that the North Passage has experienced rapid adjustment stages and adaptive stages after the construction of the *** erosion occurred along the main channel,and slow siltation could be observed in the area between the *** South Passage showed a state of upper section erosion and down section *** present,the whole South Passage is in a slight erosion *** to the numerical model,the eroding and silting speed of the North Passage will slow down in the *** present state that erosion occurs in the main channel and siltation occurs between the groins will *** South Passage will still maintain upper section erosion and down section deposition in the *** to the main channel erosion of the North Passage and siltation of the South Passage,the sediment division ratio of the North Passage will increase in the future but still be smaller than 50%.After morphological evolution of 40 years,the direction of residual sediment transport caused by M2 and M4 tidal components in the North Passage has not changed,but the transport rate will *** is considered that the morphological evolution of the North-South Passage could reach a relatively stable state after 40 years.

关键词： Yangtze Estuary numerical model morphology tidal current sediment transport deepwater navigation channel project(DNCP)

Study on Volume Variation and Stability of Riverbed in the Yangtze Estuary

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China Ocean Engineering 2023年第3期37卷 433-446页

作者： DING Lei JIAO Jian TONG Chao-feng WANG Yi-fei CHEN Ben SUN Jie-ying DOU Xi-ping Key Laboratory of Port Waterway and Sedimentation Engineering of MOTNanjing Hydraulic Research InstituteNanjing 210029China College of Harbour Coastal and Offshore EngineeringHohai UniversityNanjing 210098China State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan UniversityChengdu 610065China

In recent years,regional floods and typhoons have occurred in the Yangtze *** dynamic conditions and dramatic reduction of sediment discharge in the basin are affecting the dynamic equilibrium pattern of the Yangtze *** on the field measurement data and theoretical derivation,this paper analyzed the changing process of runoff-sediment discharge into the sea after the operation of the Three Gorges Project(TGP),and the tidal dynamics and sediment variation characteristics of the Yangtze *** erosion of South Branch mainly occurs in the channel below-10 m contour,and the riverbed volume below contours 0 m and-10 m has a good correlation with the sediment discharge of Datong Station in the previous *** this basis,the ratio of the horizontal distance from the starting point to the section centroid below the average water level(B_c)and the water depth at the section centroid(H_c)was proposed to describe the change of the section *** relationships between the water-diverting ratio,the sediment-diverting ratio and the water-diverting angle,the conditions of runoff and sediment discharge from the upper reach and the characteristics of the riverway section were established,and the theoretical calculation equations of the water-diverting ratio,the sediment-diverting ratio and the diverting angle of each bifurcation were also established.

关键词： Yangtze Estuary volume variation section shape riverbed stability

Shaping and maintaining a medium-sized main channel in the Lower Yellow River

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International Journal of Sediment Research 2012年第3期27卷 259-270页

作者： Chun-hong HU Jian-guo CHEN Qing-chao GUO State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin(SKL-WAC) China Institute of Water Resources and Hydropower Research(IWHR) International Research and Training Center on Erosion and sedimentation(IRTCES) IRTCES SKL-WAC IWHR

This paper studies relations between bankfull discharge,lateral cross section variation and the incoming flow and sediment condition in the Lower Yellow River using measured data from 1950 to *** 1950 the bankfull discharge has obviously decreased and the ratio of channel width to flow depth has *** critical annual average incoming sediment coefficient（defined as the ratio of sediment concentration to discharge） and discharge at the Huayuankou station are approximately 0.012 and 1,850 m;s;,respectively,for no accumulative deposition occurring in the reach from Huayuankou to *** this basis,a mathematical model is used to study the scale of the main channel in the Lower Yellow River and its corresponding bankfull discharge under possible incoming flow and sediment conditions in the near *** main factors influencing the scale of the main channel are analyzed,and measures to shape and maintain a medium-sized channel are *** results show the effect of various water and sediment combinations released from the Xiaolangdi Reservoir on the shaping of the main channel and suggest that under recent incoming flow and sediment conditions,it is possible to shape and maintain a medium-sized channel with a bankfull discharge of approximate 4,000 m;s;.

关键词： The Lower Yellow River Xiaolangdi Reservoir Bankfull discharge Medium size channel Flow and sediment condition

NUMERICAL SIMULATION OF SEDIMENT TRANSPORT IN ALLUVIAL RIVER WITH FLOODPLAINS

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International Journal of Sediment Research 2003年第1期18卷 50-59页

作者： Blair GREIMANN,Chih Ted YANG sedimentation and River Hydraulics Group Technical Service Center Bureau of Reclamation sedimentation and River Hydraulics Group Technical Service Center Bureau of Reclamation Hydraulic Engineer Denver CO80225 Manager Denver 11]CO

This paper presents a one-dimensional numerical model for predicting sediment transport and bed evolution in natural rivers that have floodplains. The sediment transport in floodplains is generally different from that in the main channel. Even when erosion occurs in the main channel, the floodplain usually experiences deposition. To predict the erosion and deposition in the same cross section, the river is divided into three subchannels in the transversal direction: the main channel and the left and right floodplains. The non-equilibrium sediment transport equation is modified to account for the sediment exchanges between the subchannels. The numerical model has been applied to the stretch of the Rio Grande from San Acacia Diversion Dam to Elephant Butte Reservoir. Based on a comparison with field data, the bed profile and cumulative deposition are estimated satisfactorily by the numerical model.

关键词： Alluvial river Floodplain Numerical simulation Sediment transport

Experimental Research on Boundary Shear Stress in Typical Meandering channel

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China Ocean Engineering 2018年第3期32卷 365-373页

作者： CHEN Kai-hua XIA Yun-feng ZHANG Shi-zhao WEN Yun-cheng XU Hua Nanjing Hydraulic Research Institute Nanjing 210029China College of Harbor Coastal and Offshore EngineeringHohai UniversityNanjing 210098China The State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing 210098China Key Laboratory of Port Waterway and Sedimentation Engineering of Ministry of TransportNanjing 210024China

A novel instrument named Micro-Electro-Mechanical System(MEMS) flexible hot-film shear stress sensor was used to study the boundary shear stress distribution in the generalized natural meandering open channel, and the mean sidewall shear stress distribution along the meandering channel, and the lateral boundary shear stress distribution in the typical cross-section of the meandering channel was analysed. Based on the measurement of the boundary shear stress, a semi-empirical semi-theoretical computing approach of the boundary shear stress was derived including the effects of the secondary flow, sidewall roughness factor, eddy viscosity and the additional Reynolds stress, and more importantly, for the first time, it combined the effects of the cross-section central angle and the Reynolds number into the expressions. Afterwards, a comparison between the previous research and this study was developed. Following the result, we found that the semi-empirical semi-theoretical boundary shear stress distribution algorithm can predict the boundary shear stress distribution precisely. Finally, a single factor analysis was conducted on the relationship between the average sidewall shear stress on the convex and concave bank and the flow rate, water depth, slope ratio,or the cross-section central angle of the open channel bend. The functional relationship with each of the above factors was established, and then the distance from the location of the extreme sidewall shear stress to the bottom of the open channel was deduced based on the statistical theory.

关键词： boundary shear stress flume physical model river bend MEMS flexible hot-film shear stress sensor

A three-dimensional solid-liquid two-phase turbulence model with the effect of vegetation in non-orthogonal curvilinear coordinates

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Science China(Physics,Mechanics & Astronomy) 2009年第7期52卷 1062-1073页

作者： LIU Cheng SHEN YongMing Coastal&Estuary Dynamics section Pearl River Hydraulic Research InstituteGuangzhou 510611China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116023China

A three-dimensional k-ε-Ap solid-liquid two-phase two-fluid model with the effect of vegetation is solved numerically with a finite-volume method on an adaptive grid to study water-sediment movements and bed evolution in vegetated channels. The additional drag force and additional turbulence generation due to vegetation are added to the relevant control equations for simulating the interaction between vegetation and flow. The flow structure and the bed-topography changes in a 60° partly vegetated channel bend are calculated by the model. The numerical results agree well with the measured ones. Calculated and measured results show that the primary flow velocity reduces much in the vegetation zone and increases in the non-vegetation zone, the secondary flow velocity weakens in the vegetation zone and strengthens in the non-vegetation zone, the sediment movement and bed-topography change also weaken in the vegetation zone and strengthen in the non-vegetation zone, a well-planed vegetation arrangement can improve bank stabilization program, and the k-ε-Ap model can deal with bed-load transport with a more reasonable method than the one-fluid model.

关键词： adaptive grid three dimensional k-ε-A_(p)model solid-liquid two-phase turbulence model vegetation channel bend sediment transport bed-topography change

sedimentation, RIVER GEOMETRY, AND BANK EROSION OF THE KANKAKEE RIVER IN ILLINOIS AND INDIANA

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International Journal of Sediment Research 2003年第2期 291-297页

作者： Nani G. BHOWMIK,Misganaw DEMISSIE Illinois State Water Survey Watershed Science section Illinois State Water Survey Watershed Science section Champaign IL USA Champaign IL USA

The Illinois State Water Survey has completed several reports since 1980 on sedimentation and sediment transport problems of the Kankakee River in Illinois and Indiana. The Kankakee River drains about 13,388 km2 of area, of which about 58 percent lies in Indiana and the rest in Illinois. The main stem of the Kankakee River in Indiana was channelized from about 1895 to 1918, and about 400 km of the river was reduced to about 145 to 153 km. This channelization has been associated with increased sediment load in Illinois. The present research evaluated magnitudes of bank erosion, historical changes in river geometries since 1959, and the 1978-1999 changes in in-channel sedimentation patterns. This research has shown that out of 359.8 river bank kilometers (includes both sides of the river), about 4.6 percent of the banks have severe erosion, 17.6 percent of the banks have moderate erosion, 31.7 percent of the banks have minor erosion, and 20.9 percent of the banks are protected, 20.7 percent of the banks are stable, and for 4.5 percent of the banks data are not available. The median diameter of the bed materials varied from 0.07 mm to 0.41 mm. Analyses of the long-term flows from six gaging stations in Illinois showed an increasing trend in flows through the 1960s, with no discernible increase since that time. Cross-sectional analyses of the river from the Kankakee Dam to the State Line Bridge showed some trends. The river reach from the Kankakee Dam to Aroma Park, known as the Six Mile Pool, has lost 13.4 percent of its capacity due to sediment deposition since 1980. The section of the river between Aroma Park and Singleton Ditch showed both scour and sediment deposition. In general, areas close to Aroma Park exhibited sediment deposition, and the middle reach experienced scour. The recurring sand bar at the State Line Bridge area contained about 6,495 m3 more sediment in 1999 than were measured in 1980. The river is accumulating sediments within Six Mile Po

关键词： channelization Aggradation In-channel atternatives Watershed-based alternatives