沙质床面河道演化过程湿润带渗流规律试验分析

为揭示试验室条件下无黏性沙质河道演变过程中河床湿润带的渗流规律，设计循环水槽装置系统，通过控制床沙粒径、入流流量、床面坡降及河岸植被覆盖率4个变化参量，分析不同因素对河床渗流的影响以及河床湿润带含水率的时空变化。结果表明：颗粒粒径及床面坡降对渗流流量的影响较大，粗沙的渗透性远大于细沙，流域坡降与渗流流量成正比；初始含水率对渗流有重要影响，床面初始含水率较小时，渗流流量偏大；对于河道演变试验，当床沙、坡降、河岸植被等流域控制因素一定时，系统存在相对饱和渗流流量；当流量大于相对饱和渗流流量时，渗流流量将保持相对稳定。此外，床面含水率在时间尺度上变化较小，而在空间尺度上呈区域阶梯变化。

Seepage analysis of the humid zone in the evolution process of channels with sandy riverbed

In order to reveal the seepage law of the humid zone during the formation and evolution of the non-cohesive sandy channels under laboratory conditions, a system of circulating flume is designed. The influence of different factors on the regularity of riverbed seepage flow and the tempo-spatial variation of the moisture content in the riverbed was analyzed by controlling four parameters, which are sand particle size, inflow volume, riverbed gradient and riparian vegetation coverage. The results show that the permeability of coarse sand is much larger than that of fine sand, and the slope of the basin is proportional to the seepage flow. The riverbed with smaller initial moisture content has a larger seepage flow. When the control factors such as riverbed sand, gradient and riparian vegetation are certain, there is a relatively saturated seepage flow in the channel evolution tests. When the flow is greater than the relative saturation seepage flow, the seepage flow will remain relatively stable. In addition, the moisture content of the riverbed surface changes slightly at the time scale, but shows a stepped change from one region to another at the spatial scale.