高级检索

    重庆缙云山典型林地地表径流水力学参数研究

    Hydraulic parameters of surface runoff in typical forest sites of Jinyun Mountain, Chongqing City of southwestern China

    • 摘要: 为揭示重庆缙云山森林植被的水文生态过程,选取裸地、针阔混交林、常绿阔叶林和楠竹林4种不同土地利用类型,采用放水冲刷径流试验方法,设计0.12、0.18、0.24、0.30、0.36L/min 5种不同的流量,测定蓄满产流下的地表径流水力学参数。结果表明:1)在放水冲刷条件下,4种地类径流阻力系数随流量的增大而降低,说明地表枯落物、有机质和根系能有效增加坡面糙度和阻力;随着流量的增大,径流冲走枯落物和有机质并形成细沟,浅层根系对径流的阻力效果增强,而根系较深的地类其阻力系数逐渐趋近于裸地的;2)4种不同地类的流速随着流量的增加而增加,地表枯落物和植物根茎对流速有减缓作用,且在大流量情况下,楠竹林根系对流速的消减作用更明显;3)在试验条件下,随着流量的增加,雷诺数持续增加,其径流特性由层流向紊流转变;弗劳德数先减小后增加,流量在0.18~0.30L/min之间取得弗劳德数的最小值。相同流量下,雷诺数和弗劳德数的大小顺序均为裸地>针阔混交林>常绿阔叶林>楠竹林。

       

      Abstract: We selected four land use types, i.e. bare field, mixed broadleaf-conifer forest, evergreen broadleaved forest and bamboo forest, and carried out scouring experiments with five different flows of 0.12, 0.18, 0.24, 0.30, and 0.36L/min to study the eco-hydrological processes of forest vegetation in Jinyun Mountain, Chongqing City of southwestern China. The hydraulic parameters of surface runoff under saturated storage were measured. The results showed that: 1) Darcy-Weisbach coefficient of the four types of forest lands decreased with increasing flow rate, indicating that litters, organic matters and roots on the ground may increase the roughness and surface resistance effectively. As the flow increased, rills were formed after litters and organic matters were flowed away, then the effects of shallow root system against runoff would be enhanced significantly. However, the amount of coefficient of woodland with deep roots gradually approached to that of bare field. 2) The flow velocity of four land use types had a positive correlation with flow rate. Litter and roots could slow down the runoff velocity, especially in bamboo forest while in higher flows. 3) As the amount of flux increased, the Reynolds number increased and runoff characteristics transformed from laminar to turbulent; Froude's number decreased to a minimum value at the amount of flux between 0.18 and 0.30L/min and then increased. Under the same flow amount, the order of Reynolds and Froude's number was bare field > mixed broadleaf-conifer forest > evergreen broadleaved forest > bamboo forest.

       

    /

    返回文章
    返回