黄土高原坡沟系统径流水动力学特性试验

Experiments on hydraulic characteristics of runoff in slope-gully systems in Loess Plateau

为了研究坡沟系统中坡面与沟道之间的侵蚀产沙关系,该研究采用双坡段(坡面和沟坡)组合模型,通过室内放水冲刷试验,结合REE示踪技术,研究了黄土高原地区径流的水动力学特性。结果表明:在试验流量范围内,坡沟系统径流雷诺数变化位于342.3～858.8之间,且变化幅度随冲刷历时的增大而增大;弗罗德数变化位于1.36～8.92之间,且具有时空分异特征。相同流量下,坡沟系统的坡面径流流速沿程有先增大后减小的趋势,在从坡面向沟坡过渡时,各流量下的流速均达到极小值,进入沟坡以后,流速又开始增大。当流量相同时,Darcy-Weisbach阻力系数和曼宁糙率系数沿程均呈先减小后增大然后再减小的趋势。该研究为黄土高原坡沟系统侵蚀产沙模型的建立提供理论依据。

In order to study the relationship between erosion and sediment yield in slope and gully, the hydraulic characteristics of runoff in slope-gully systems were studied in this paper by dual slope segment combination model, through the indoor scouring test, combined with REE tracer technique. The results showed that the changes of runoff Reynolds number （Re） in the slope-gully systems was located between 342.3 and 858.8, and the magnitude of changes increased with the increasing of erosion lasted time in the range of experimental flow. The changes of Froude number （Fr） in the slope-gully systems was varied between 1.36 and 8.92, and it had a spatial and temporal variation characteristic in the range of experimental flow. The runoff velocity of slope in slope-gully systems first increased then decreased under the condition of the same flow. The flow velocity reached a minimum value when runoff transition from slope to gully. It began to increase again after flow into gully. Darcy-Weisbach drag coefficient and Manning roughness coefficient firstly decreased, then increased and then decreased with test section from top to bottom in the same flow. The study can provide a theoretical basis for foundation of erosion and sediment yield model of slope-gully systems in Loess Plateau.