Flow resistance estimate is a challenging topic for establishing flooding propensity of streams, designing river restoration works, and evaluating the use of soil bioengineering practices. In this paper, flume measurements with rigid cylinders set in two arrangements (aligned, staggered) were used to evaluate the effect of rigid emergent vegetation on flow resistance. A well‐known theoretical flow resistance equation was firstly reviewed. Then, it was calibrated and tested by measurements performed for these arrangements with six concentrations (0.53–11.62 stems dm−2). The analysis was conducted using three approaches: (i) distinguishing the experimental runs corresponding to different arrangements and stem concentrations; (ii) using only a scale factor representing the effect of the stem concentration; and (iii) joining all available data. The results demonstrated that the flow resistance equation gives an accurate estimate of the Darcy–Weisbach friction factor f, characterized, for the best approach among the tested ones, by errors less than or equal to ±5% for 95.9% of the examined cases for the aligned arrangement and for the staggered arrangement less than or equal to ±5% for 94.2% of the examined cases. For both arrangements, the measurements demonstrated that, for a given longitudinal distance between vegetation elements, flow resistance increases for decreasing values of the transverse distance and, for a given transverse distance, f decreases for increasing values of the longitudinal distance between elements. Finally, in the range of the investigated stem concentrations, the influence of the arrangement on flow resistance resulted negligible.

中文翻译：

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具有挺水刚性植被的河道水流阻力规律

流阻估计对于确定溪流的洪水倾向、设计河流恢复工程以及评估土壤生物工程实践的使用来说是一个具有挑战性的课题。在本文中，使用两种布置（对齐、交错）的刚性圆柱体进行水槽测量，以评估刚性挺水植被对流动阻力的影响。首先回顾了著名的理论流阻方程。然后，通过对六种浓度（0.53–11.62 茎干分米）的这些排列进行测量来对其进行校准和测试。−2）。使用三种方法进行分析：（i）区分对应于不同排列和茎浓度的实验运行； (ii) 仅使用代表茎浓度影响的比例因子； (iii) 加入所有可用数据。结果表明，流阻方程可以准确估计达西-魏斯巴赫摩擦系数F，其特征在于，对于测试中的最佳方法，对于对齐排列的 95.9% 的检查案例，误差小于或等于 ±5%；对于交错排列，94.2% 的检查案例的误差小于或等于 ±5%。审查的案件。对于这两种布置，测量表明，对于植被元素之间给定的纵向距离，流动阻力随着横向距离的减小而增加，并且对于给定的横向距离，F随着元件之间的纵向距离值的增加而减小。最后，在所研究的茎浓度范围内，布置对流动阻力的影响可以忽略不计。