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Testing a theoretical resistance law for overland flow under simulated rainfall with different types of vegetation
Catena ( IF 5.4 ) Pub Date : 2020-01-30 , DOI: 10.1016/j.catena.2020.104482
A. Nicosia , C. Di Stefano , V. Pampalone , V. Palmeri , V. Ferro , V. Polyakov , M.A. Nearing

In this paper a recently theoretically deduced flow resistance equation, based on a power-velocity profile, was tested using data collected for overland flow under simulated rainfall carried out in plots with vegetation. The available data were obtained exploring a wide range of rainfall intensities (from 60 to 181 mm h−1) and slopes (from 3.6 to 39.6%), and with four different types of vegetation. The database, including measurements of flow velocity, water depth, cross sectional flow area, wetted perimeter and bed slope, was divided in four datasets (one for each vegetation type), which allowed the calibration of the relationship between the velocity profile parameter Γ, the slope steepness, the flow Froude number, and the rainfall Reynolds number. The effect of rainfall intensity and different types of vegetation on flow resistance was investigated.

The results showed that the theoretically deduced flow resistance equation allowed an accurate estimate of the Darcy-Weisbach friction factor for overland flow under simulated rainfall and in presence of vegetation. The developed analysis also suggested that flow resistance increases with rainfall intensity for laminar overland flow. The available data demonstrated that a quasi-independence between slope and mean velocity occurred. Finally, a single flow resistance equation resulted applicable to all investigated vegetation types and this equation was affected by flow regime represented by flow Reynolds number.



中文翻译:

测试不同类型植被的模拟降雨下的陆流理论阻力定律

在本文中,使用在植被带样地进行的模拟降雨条件下收集的陆上水流数据,对基于功率-速度剖面的最近理论推导的水流阻力方程进行了测试。可获得的数据是在广泛的降雨强度(60至181 mmh -1)和坡度(从3.6到39.6%),以及四种不同类型的植被。该数据库包括流速,水深,横断面流量面积,湿润周长和河床坡度的测量值,被划分为四个数据集(每种植被类型一个),从而可以校准速度剖面参数Γ,坡度,流量弗洛德数和降雨雷诺数。研究了降雨强度和不同植被类型对流阻的影响。

结果表明,从理论上推导的流阻方程可以准确估算模拟降雨和植被存在下的陆流的达西-魏斯巴赫摩擦因数。发达的分析还表明,层流性陆流的阻力随着降雨强度的增加而增加。现有数据表明,斜率与平均速度之间存在准独立性。最后,得出一个适用于所有调查植被类型的流阻方程,该方程受到以雷诺数表示的流态的影响。

更新日期:2020-01-31
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