河床沉积物非均质性影响下的潜流交换数值模拟  

Modeling the impacts of streambed sediment heterogeneity on hyporheic exchange

作　　者：陈孝兵 郑春阳[2] 袁越 CHEN Xiaobing;ZHENG Chunyang;YUAN Yue(State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,Hohai University,Nanjing 210098,China;ollege of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210098,China)

机构地区：[1]河海大学水文水资源与水利工程科学国家重点实验室,江苏南京210098 [2]河海大学水利水电学院,江苏南京210098

出　　处：《水科学进展》2019年第2期220-229,共10页Advances in Water Science

基　　金：国家重点研发计划资助项目(2016YFC0402703);国家自然科学基金资助项目(41771033)~~

摘　　要：为了揭示河床沉积物非均质性对潜流交换的影响,构建了沙波地形作用下的地表水-地下水耦合模型,通过生成不同的渗透系数随机场,讨论了不同地表水动力过程和河床沉积物非均质性对潜流交换通量、交换空间及平均停留时间的影响规律。结果表明,所构建的地表水-地下水耦合模型能够准确刻画水沙界面附近流场,模型具有良好的适用性;均质或非均质河床沉积物情景下,水沙界面上的平均交换通量、停留时间与雷诺数之间均呈现幂函数关系,潜流交换深度则在地表水进入完全紊流之后趋于稳定。结果还表明,较强的河床沉积物非均质性能够有效增强水沙界面上潜流交换通量和空间交换频率,但会制约潜流交换空间并缩短水流在潜流带中的停留时间。The hyporheic exchange plays a crucial role in maintaining fluvial ecological processes. In order to examine the influence of streambed heterogeneity on the hyporheic exchange,a surface water-groundwater coupling model is constructed for solving flow interactions over a sand dune. By generating different permeability random fields,the influences of hydrodynamic processes and streambed heterogeneity on the hyporheic exchange flux,exchange space and mean residence time are addressed. The results showed that the coupling model has good performance and it can accurately depict the flow fields near the sediment-water interface. Under homogeneous or heterogeneous scenarios,the mean exchange flux and bulk residence time via Reynolds number are representing power law relationships,and the mean exchanged depth tends to be stable after the surface flow transitions into highly turbulent conditions. Results further shown that higher heterogeneity can effectively enhance the hyporheic exchange flux and spatial exchange frequency along the sediment-water interface. However,it will restrict the exchange volume and shorten the mean residence time of flow in the hyporheic zone.

关 键 词：河床沉积物 非均质性 潜流交换 数值模拟 地表水-地下水交互 

分 类 号：TV138[水利工程—水力学及河流动力学]