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Gravel excavation and geomorphic evolution of the mining affected river in the upstream reach of the Yangtze River,China

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International Journal of Sediment Research 2022年第2期37卷 272-286页

作者： Yi Xiao Wenjie Li Shengfa Yang National Inland Waterway Regulation Engineering Research Center Chongqing Jiaotong University

As economic development upstream in the Yangtze River basin has progressed in recent decades,the demand for sediment has rapidly increased and contributed to an expansion in sediment excavation that may affect the river's stability and navigation safety.In the current study,the distribution of gravel mining in the upstream reach of the Yangtze River was investigated using field measurements obtained from2008 to 2017.An experimental investigation was then done to analyze the bed load behavior in a typical mined channel using a physical river model.Finally,a two-dimensional hydrodynamic-sediment transport numerical model was developed to predict the evolution of the mined channel.The results indicate that gravel mining was mainly distributed among the following nine river sections:Tongluoxia-Yibin,Erlong-Xianglutan,Naxi-Jinkou,Binpangqi-Hongyanqi,Chayuqi-Shenbeizui,Yangshipan-Shangbaisha,dongxikou,Baisha-Wenzhongba,and Jiangjin-Shenzhongba.The gravel shoals near the riverbank have been destroyed,and the bed topography has been altered by up to 1.65 × 10～9 m3over the past 10 years.A bed load velocity formula was proposed to describe bed load transport in the mined channel based on dimensional analysis.The recovery process of the excavation pits was slow in both the experiments and simulations,with only 0.12% and 1.39%,respectively,of the mined amounts of gravel being restored.Finally,the recovery rate of the mining pits gradually slowed as the sediment supply from upstream decreased,suggesting that the destroyed gravel shoals rarely returned to their original forms due to the combined operation of hydro-projects in upstream areas and limited sediment storage in the channel.

关键词： Gravel mining Bed load transport Channel evolution Yangtze River upstream 2d numerical model

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Formation process of meandering channel by a 2d numerical simulation

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International Journal of Sediment Research 2012年第3期27卷 306-322页

作者： Yi XIAO Xue-jun SHAO Hong WANG Gang ZHOU State Key Laboratory of Hydroscience and Engineering Tsinghua University Post-doctoral research fellow Chinese Research Academy of Environmental Sciences

A 2d depth-averaged model for hydrodynamic,sediment transport and river morphological adjustment is presented.The sediment transport submodel considers non-uniform sediment,bed surface armoring,impact of secondary flow on the direction of bed-load transport,and transverse slope of river bed.The bank erosion submodel incorporates a simple simulation method for updating bank geometry during either degradational or aggradational bed evolution.The model is applied to a 180°bend with a constant radius under unsteady flow conditions,and to Friedkin’s laboratory meander channels.The results are in acceptable agreement with measurements,confirming the two dimensional model’s potential in predicting the formation of river meandering and improving understanding of patterning processes.Future researches are needed to clarify some simplifications and limitations of the model.

关键词： River morphology Armored beds Non-uniform sediment Bank erosion 2d numerical model

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numerical modelING OF SUSPENdEd SEdIMENT TRANSPORT IN CHANNEL BENdS

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Journal of Hydrodynamics 2006年第4期18卷 411-417页

作者： HUANG Sui-liang JIAY．F,WANG Sam S. Y. College of Environmental Science and Engineering Nankai University Tianjin 300071 China National Center for Computational Hydroscience and Engineering The University of Mississippi Oxford USA

An algorithm to compute three-dimensional sediment transport effect was proposed in this paper to enhance the capability of depth-averaged numerical models. This algorithm took into account of non-uniform distributions of flow velocities and suspended sediment concentrations along water depth, it significantly enhanced the applicability of 2d models in simulating open channel flows, especially in channel bends. Preliminary numerical experiments in a U-shaped and a sine-generated experimental channel indicate that the proposed method performs quite well in predicting the change of bed-deformation in channel bends due to suspended sediment transport. This method provides an effective alternative for the simulations of channel morphodynamic changes.

关键词： algorithm dispersion terms bends suspended sediment transport 2d numerical model

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Quasi-3d numerical Simulation of Tidal Hydrodynamic Field

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China Ocean Engineering 1999年第3期14卷 265-276页

作者：宋志尧薛鸿超严以新茅丽华徐福敏 College of Harbor Waterway and Coastal Engineering Hohai University (HHU) Nanjing 210098 China College of Harbor Waterway and Coastal Engineering HHU Nanjing 210098 China

Based on the 2d horizontal plane numerical model, a quasi-3d numerical model is established for coastal regions of shallow water. The characteristics of this model are that the velocity profiles;can be obtained at the same time when the equations of the value of difference between the horizontal current velocity and its depth-averaged velocity in the vertical direction are solved and the results obtained are consistent with the results of the 2d, model. The circulating flow in the rectangular area induced by wind is simulated and applied to the tidal flow field of the radial sandbanks in the South Yellow Sea. The computational results from this quasi-3d model are in good agreement with analytical results and observed data. The solution of the finite difference equations has been found to be stable, and the model is simple, effective and practical.

关键词： tidal hydrodynamic field quasi-3d numerical model 2d numerical model velocity profile numerical simulation

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numerical modeling of Sediment Transport and Its Effect on Algal Biomass distribution in Lake Pontchartrain due to Flood Release from Bonnet CarréSpillway

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Journal of Geoscience and Environment Protection 2016年第9期4卷 64-79页

作者： Xiaobo Chao Yafei Jia A. K. M. Azad Hossain National Center for Computational Hydroscience and Engineering University of Mississippi Oxford USA

In order to protect the city of New Orleans from the Mississippi River flooding, the Bonnet Carré Spillway (BCS) was constructed from 1929 to 1936 to divert flood water from the river into Lake Pontchartrain and then into the Gulf of Mexico. during the BCS opening for flood release, large amounts of freshwater, nutrients, sediment, etc. were discharged into Lake Pontchartrain, and caused a lot of environmental problems. To evaluate the environmental impacts of the flood water on lake ecosystems, a two-dimensional numerical model was developed based on CCHE2d and applied to simulate the flow circulation, sediment transport and algal biomass distribution in Lake Pontchartrain. The effect of sediment concentration on the growth of algae was considered in the model. The numerical model was calibrated using field measured data provided by USGS, and then it was validated by the BCS Opening Event in 1997. The simulated results were generally in good agreement with filed data and satellite imagery. The field observation and numerical model show that during the spillway opening for flood release, the sediment concentration is very high, which greatly restricts the growth of algae, so there is no algal bloom observed in the lake. After the closure of BCS, the sediment concentration in the lake reduces gradually, and the nutrient concentration of the lake is still high. Under these conditions, numerical results and satellite imagery showed that the chlorophyll concentration was high and algal bloom might occur.

关键词： 2d numerical model Flow Circulation Sediment Transport Algal Bloom Bonnet Carré Spillway Lake Pontchartrain

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