模拟植被地表覆盖率和粗糙度对坡面流水动力特性的影响

发布时间：2018-04-11 08:07

本文选题：坡面流 + 植被覆盖　；参考：《水土保持学报》2017年06期

【摘要】：为研究刚性植被覆盖与地表粗糙共同作用下的坡面流水动力特性,在室内开展定床水槽冲刷试验,研究陡坡(15°)条件下10组流量(0.33~1.95m~3/h)、5种覆盖率(0,0.5%,1.0%,1.5%,2.0%)、4种不同地表粗糙度(0.01,0.18,0.25,0.38mm)的坡面流流速、流型流态、阻力系数等变化特性。结果表明:(1)水流流速变动范围为0.06~0.59m/s,流速与植被覆盖率和地表粗糙度呈负相关关系(r-0.90),当植被覆盖率增加,流速随流量增加的增幅降低;流速校正系数与植被覆盖率呈正相关关系(r0.75),而与地表粗糙度呈负相关关系(r-0.84);(2)所有试验条件下雷诺数处于153~910之间,流态主要集中于过渡区和虚拟层流区,流型多数处于急流区,随植被覆盖率和地表粗糙度的增加,弗劳德数逐渐小于1,具有向缓流区延伸的趋势;(3)坡面流总阻力系数与雷诺数呈幂函数关系,与地表粗糙度和植被覆盖率呈正相关关系(r0.81);(4)阻力影响指数结果显示,当流量小于1.05m~3/h时,地表粗糙度在影响总阻力过程中占主导地位,反之,植被覆盖率占主导地位;通过t检验,坡面流总阻力与颗粒阻力和形态阻力线性叠加结果差异性显著(p0.05),表明当存在颗粒阻力及形态阻力时,坡面流总阻力并不能使用线性叠加原理。
[Abstract]:Flow pattern, resistance coefficient and other variation characteristics.The results show that the variation range of flow velocity is 0.06 ~ 0.59 m / s, and the velocity is negatively related to vegetation coverage and surface roughness. When vegetation coverage increases, the increase of velocity decreases with the increase of flow rate.The velocity correction coefficient has a positive correlation with vegetation coverage, but a negative correlation with surface roughness.) under all experimental conditions, the Reynolds number is between 153 and 910. The flow pattern is mainly concentrated in the transition zone and virtual laminar flow zone, and most of the flow patterns are in the jet flow area.With the increase of vegetation coverage and surface roughness, the Froude number is gradually less than 1, which has the tendency of extending to the slow flow area. (3) the total resistance coefficient of the slope flow has a power function relationship with the Reynolds number.There is a positive correlation between surface roughness and vegetation coverage. The results show that when the flow is less than 1.05m~3/h, the surface roughness plays a dominant role in the total resistance, whereas vegetation coverage occupies the dominant position.Through t test, the difference of linear superposition between total resistance of slope flow and particle resistance and shape resistance is significant (p 0.05), which indicates that when there is particle resistance and shape resistance, the principle of linear superposition can not be used in the total resistance of slope flow.
【作者单位】：北京林业大学水土保持学院;北京林业大学重庆缙云三峡库区森林生态系统国家定位观测研究站;
【分类号】：S157

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