床面形态驱动下潜流交换试验  

Experimental study of bedform-driven hyporheic exchange

作　　者：陈孝兵[1] 赵坚[2] 李英玉[2] 陈力[1] 

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》2014年第6期835-841,共7页Advances in Water Science

基　　金：国家自然科学基金资助项目(41401014;51279045)~~

摘　　要：为揭示河床形态特征引起的潜流交换规律,构建循环式水槽装置,通过Na Cl示踪对比分析了4种河床地形驱动下的潜流交换规律,并基于扩散理论探讨了潜流交换与地表水水动力及床沙渗透特性之间的关系。结果表明,潜流交换可以发生在平坦河床地形,且交换速率随地形起伏度和雷诺数的增大而增大;在相似的地形条件下,地表流速是影响潜流交换速率的主导因素,地表水深对潜流交换速率影响较弱;此外,分析表明,有效扩散系数与河床特征粒径之间具有2次方幂率函数关系,且与河床渗透系数成正比;交换深度d正比于雷诺数Re的1/2次方。In order to test the bedform impacts on the hyporheic exchange behavior, the tracer NaC1 is used to test the hyporheic exchanges under four groups of bedforms in a water-circling flume. Based on the diffusion theory, the impacts of hydrodynamics of water column and permeability of underlying sediments on the hyporheic flow are analyzed. Results show that the hyporheie exchanges can occur on a fiat bedform. The exchange rate can be intensified under a more uneven bedform and a higher Reynolds number. Compared to the factor of water depth, the hyporheic exchange rate is much more sensitive to the velocity of the surface water. In addition, the effective diffusion coefficient is proportional to the square of characteristic grain diameter, and has a linear relationship with the streambed hydraulic conductivity. Also, the exchange depth in the flume is found to be proportional to the Re^1/2.

关 键 词：河床形态 水槽试验 潜流交换 有效扩散系数 

分 类 号：TV131[水利工程—水力学及河流动力学]