不同高度柔性植被对坡面流水动力特性的影响

基于系列坡面流试验,研究了柔性植被的高度(4 cm,8 cm和15 cm)对坡面流水动力特性的影响.研究表明:覆盖率相同时,4 cm植被阻水效果最好,15cm最差,而该差异随着坡度增大而减小.4 cm和8 cm植被覆盖时,水流阻力系数随雷诺数增加先减小后增加,这是由于雷诺数较小时水流阻力主要以床面阻力为主,雷诺增大时主要以植被阻力为主.另外,通过染色剂法测得光滑床面平均流速修正系数为0.2～0.4,有植被覆盖床面为0.4～0.8,且修正系数随平均流速增大而增大.

EXPERIMENTAL STUDY OF THE EFFECTS OF DIFFERENT HEIGHT FLEXIBLE VEGETATION ON HYDRAULIC CHARACTERISTICS OF OVERLAND FLOW

A series of overland flow experiments are conducted, focusing on the effects of the different height flexible vegetation on the hydraulic characteristics of the overland flow. Experimental results show that the 4 cm vegetation shows the best effect on the overland flow while the 15 cm vegetation shows the least effect. The difference of the effects reduces with the increase of the slope. With the same coverage rate, the flow resistance increases and then decreases with the increase of the Reynold's number. That is because the main flow resistance is the bed resistance in case of a small Reynold's number while the vegetation resistance prevails in case of a large Reynold's number. Besides, the revised coefficient ranges from 0.2 to 0.4 on smooth slopes while 0.4 to 0.8 on vegetation slopes, and the revised coefficient increases with the increase of the averaged velocity.