Rill erosion is considered one of the most important soil processes because of the large amount of soil loss due to the development of a rill network able to promote an efficient transport of both rill flow-detached particles and those delivered from the inter-rill areas. Rill flow experiments are useful to overcome the gap in rill hydraulics knowledge and to test the reliability of currently applied uniform open channel flow equations for mobile bed rills. In this paper the applicability of a theoretical flow resistance equation, based on a power-velocity profile, to rill channels shaped on soils having different textures was investigated. The measurements (437 runs) of water depth, cross-section area, wetted perimeter, bed slope and flow velocity carried out in rill reaches shaped on experimental plots, having different slope values (9–26%) and soil texture (clay fraction range of 32.7–73%), were carried out. These measurements were jointly examined with 35 experimental runs carried out by other authors in a rill flume having a slope range of 18–84% and a clay content of 3%. The main aim of this paper is to deduce a relationship between the velocity profile parameter Γ, the channel slope and the flow Froude number using a database characterized by a wide range of slope (9–84%) and textural classes (clay ranging from 3 to 73%). The obtained relationship was also verified using 117 experimental runs carried out in this investigation by sloping plots (slope equal to 9 and 15%) with a soil having a clay content of 32.7%. The analysis demonstrated that the applicability of the theoretical flow resistance law is experimentally supported and that the effect of soil grain-size distribution is represented by silt and clay fractions which take into account the influence of the detachability and transportability properties of the soil particles.

中文翻译：

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不同质地土壤中移动式河床的流阻

细沟侵蚀被认为是最重要的土壤过程之一，因为细沟网络的发展导致大量土壤流失，能够促进细沟流分离颗粒和从细沟间区域输送的颗粒的有效运输。细沟流实验有助于克服细沟水力学知识的空白，并测试当前应用于移动式底细沟的均匀明渠流动方程的可靠性。在本文中，研究了基于功率-速度剖面的理论流阻方程对不同质地土壤上形成的细沟的适用性。水深、截面积、湿周、河床坡度和流速的测量（437 次）在试验样地形成的细沟中进行，进行了具有不同坡度值（9-26%）和土壤质地（粘土比例范围为 32.7-73%）的试验。这些测量结果与其他作者在坡度范围为 18-84% 和粘土含量为 3% 的细沟中进行的 35 次实验运行联合检查。本文的主要目的是使用以大范围斜率 (9–84%) 和质地类别（粘土范围从 3到 73%）。所获得的关系也使用在本次调查中通过具有 32.7% 粘土含量的土壤的倾斜地块（坡度等于 9 和 15%）进行的 117 次实验运行进行了验证。