含沙水流在植被斑块中的输沙规律及阻力机制试验  

Experiment of the sediment transport pattern and resistance mechanism for sand-bearing flow in vegetation patches

作　　者：李佳颐 宋艳暾[1] 蔡崇法[1] 郝蓉[1] 占昌华 温希望 LI Jiayi;SONG Yantun;CAI Chongfa;HAO Rong;ZHAN Changhua;WEN Xiwang(College of Resources and Environment,Huazhong Agricultural University,Wuhan 430070,China)

机构地区：[1]华中农业大学资源与环境学院,武汉430070

出　　处：《农业工程学报》2023年第12期95-103,共9页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金项目(U2240222),国家自然科学基金项目(41877528);国家重点研发计划课题(2021YFD1500703)。

摘　　要：为深入探究自然状态下含植被水沙运动过程及植被阻水拦沙机理,利用室内开闸式平坡水槽试验研究了泥沙粒径级配、植被冠层形态特征、植被密度对含沙水流输沙规律及阻力机制的影响。提出植物叶片长宽比作为衡量单株植物的冠层形态特征指标,用无量纲沉积通量和不同尺度下的无量纲冠层阻力划分含沙水流运动状态,掲示冠层形态特征及泥沙粒径级配对含沙水流运动过程的影响。研究结果表明,含沙水流中泥沙沉积通量受植物冠层形态和粗粒径悬移质(10~100μm的弱黏性颗粒)含量影响,且植被冠层形态及泥沙粒径级配与无量纲沉积通量之间在阻力主导阶段存在强烈的反馈机制。植被冠层形态较大或粗粒径悬移质含量高的含沙水流中,沿水流运动方向床沙细化趋势更显著。相较于受叶片长宽比影响的冠层形态特征及植被密度,悬移质泥沙粒径级配因素对植被阻水拦沙效果的影响程度较为微弱。研究成果可为流域侵蚀输沙过程和河流水沙资源管理提供一定的科学依据。Erosion and sediment transport can vary greatly with the change of spatial and temporal scales in the continuous system from slope water flow to the river channel.The vegetation can be the main driver of the spatial and temporal evolution in the water flow structure,sediment erosion transport,and landscape patterns,as the landscape gradient decreases.It is worth noting that vegetation morphology and canopy structure are important factors to determine the impacts of vegetation on the fluid structure and sediment transport.In addition,the properties of sediment are also the key to clarifying the turbidity currents transport pattern in the natural environment.However,there is a lack of attention to the above two points in the available studies.In this study,the simulated plants were utilized using Acorus calamus L.and Abutilon theophrasti Medicus to deploy the vegetation patches of different densities in a randomized distribution,in order to configure with the natural sediment in different grain size gradations of turbidity currents.A lock-exchange flume experiment was carried out to clarify the influence of vegetation patches with the natural plant canopy morphological characteristics on the turbidity currents transport pattern and resistance.The feedback mechanism was also studied between the sediment grain size gradation factor and the turbidity currents movement pattern.The plant leaf length-width ratio was proposed as a measure of the change in the canopy morphological characteristics.The influence of canopy morphological characteristics and sediment grain size class on turbidity currents flow was expressed,in terms of the non-dimensional canopy dragforce at the plant stem scale CDaad,the nondimensional canopy dragforce at each position CDaax,and the non-dimensional depositional flux DF.The results in the test conditions were as follows:1)The transport and deposition processes of turbidity currents were influenced by the morphology of the plant canopy and the content of coarse-grained suspended material(weakly

关 键 词：泥沙 粒径 含沙水流 植被阻力 冠层形态 水槽试验 

分 类 号：S27[农业科学—农业水土工程] TV157[农业科学—农业工程]