In this paper, the morphology of step–pool features is analysed using rill measurements and literature data for streams. Close‐range photogrammetry was used to carry out ground measurements on rills with step–pool units, shaped on a plot having slope equal to 14, 15, 22, 24 and 26%. Data were used to compare the relationships between H/L, in which H is the step height and L is the step length, and the mean gradient of the step–pool sequence, S_m, for streams or the slope of the step–pool unit, S, for rills. The relationship of H/L against S_m is widely used to test the occurrence of the maximum flow resistance condition in streams, which is associated with the range 1 ≤ (H/L)/S_m ≤ 2. Further analyses were carried out to compare both the formation process and the profile of the pool in rills with those related to streams. Moreover, for a single rill channel, an analysis of flow characteristics expressed in terms of Darcy–Weisbach friction factor and Froude number was developed. The results allowed us to state: (i) the relationships of H/L versus S_m and S are quite similar and the steepness ratio for streams, (H/L)/S_m, and for rills, (H/L)/S, generally ranges from 1 to 2; (ii) the formation process and the profile of the pool in rills are not consistent with those occurring in streams; (iii) in the rills, the longitudinal size of the pool is dominant with respect to the maximum scour depth; (iv) the presence of a sequence of step–pool units within a rill segment noticeably increases flow resistance compared to segments with a flat bed; (v) the Froude number of the flow over the sequence of step–pool units in rills is slightly below the range of 0.8–1 corresponding to the maximum flow resistance in step–pool units.

中文翻译：

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小溪阶梯池形态分析及其与河床情况的比较

在本文中，使用小溪测量和溪流文献数据分析了阶梯池特征的形态。近距离摄影测量法被用于对具有阶梯池单元的小溪进行地面测量，该单元的坡度等于14％，15％，22％，24％和26％。数据用于比较H / L之间的关系，其中H是阶跃高度，L是阶跃长度，以及阶跃-池序列的平均梯度S _m对于流或阶跃-池的斜率小队的单位S。的关系ħ /大号对小号_米被广泛地用于测试流的最大流动阻力条件下，其与范围为1相关联的发生≤（ħ /大号）/小号_米≤2.进一步的分析进行了比较的形成过程和的轮廓二者与小溪相关的小溪中的游泳池。此外，对于单个钻洞通道，已进行了以达西-魏斯巴赫摩擦因数和弗洛德数表示的流动特性分析。结果使我们可以陈述：（i）H / L与S _m和S的关系非常相似，并且流的陡度比（H / L）/S _m，对于小溪，（H / L）/ S通常为1到2；（ii）小溪中水池的形成过程和轮廓与溪流中形成的不一致；（iii）在小溪中，相对于最大冲刷深度，水池的纵向尺寸占主导地位；（iv）与平床段相比，小溪段内有一系列阶梯池单元显着增加了流动阻力；（v）在小溪中，阶梯池单元序列上的弗洛德数略低于0.8-1的范围，该范围与阶梯池单元中的最大流动阻力相对应。