Department of Agricultural and Forestry Sciences, University of Palermo, Viale delle Scienze, 90128 Palermo, Italy.
Department of Earth and Marine Sciences, University of Palermo, Via Archirafi 20, 90123 Palermo, Italy.
Sci Total Environ. 2017 Dec 15;603-604:244-255. doi: 10.1016/j.scitotenv.2017.06.009. Epub 2017 Jun 23.
In the past badlands have been often considered as ideal field laboratories for studying landscape evolution because of their geometrical similarity to larger fluvial systems. For a given hydrological process, no scientific proof exists that badlands can be considered a model of river basin prototypes. In this paper the measurements carried out on 45 Sicilian calanchi, a type of badlands that appears as a small-scale hydrographic unit, are used to establish their morphological similarity with river systems whose data are available in the literature. At first the geomorphological similarity is studied by identifying the dimensionless groups, which can assume the same value or a scaled one in a fixed ratio, representing drainage basin shape, stream network and relief properties. Then, for each property, the dimensionless groups are calculated for the investigated calanchi and the river basins and their corresponding scale ratio is evaluated. The applicability of Hack's, Horton's and Melton's laws for establishing similarity criteria is also tested. The developed analysis allows to conclude that a quantitative morphological similarity between calanco landforms and river basins can be established using commonly applied dimensionless groups. In particular, the analysis showed that i) calanchi and river basins have a geometrically similar shape respect to the parameters Rf and Re with a scale factor close to 1, ii) calanchi and river basins are similar respect to the bifurcation and length ratios (λ=1), iii) for the investigated calanchi the Melton number assumes values less than that (0.694) corresponding to the river case and a scale ratio ranging from 0.52 and 0.78 can be used, iv) calanchi and river basins have similar mean relief ratio values (λ=1.13) and v) calanchi present active geomorphic processes and therefore fall in a more juvenile stage with respect to river basins.
在过去，荒地常被认为是研究景观演化的理想野外实验室，因为它们在几何形状上与更大的河流系统相似。对于给定的水文过程，没有科学证据表明荒地可以被视为流域原型的模型。本文利用在 45 个西西里卡拉奇（一种出现在小规模水文单元中的荒地类型）上进行的测量，来建立它们与可在文献中获得数据的河流系统的形态相似性。首先，通过确定可以取相同值或按固定比例缩放的值的无量纲组，来研究地貌相似性，这些无量纲组代表流域形状、水系和地形特征。然后，针对每个特征，计算研究中的卡拉奇和河流流域的无量纲组，并评估其相应的缩放比例。还测试了 Hack、Horton 和 Melton 定律在建立相似性标准中的适用性。所开发的分析允许得出结论，即可以使用常用的无量纲组建立卡拉奇地貌和流域之间的定量形态相似性。特别是，该分析表明：i）卡拉奇和河流流域在几何形状上具有相似的形状，与 Rf 和 Re 参数有关，比例因子接近 1；ii）卡拉奇和河流流域在分叉和长度比（λ=1）方面相似；iii）对于研究中的卡拉奇，梅尔顿数（Melton number）取值小于相应河流情况的数值（0.694），并且可以使用 0.52 到 0.78 的比例因子；iv）卡拉奇和河流流域具有相似的平均地形比（λ=1.13）；v）卡拉奇存在活跃的地貌过程，因此相对于河流流域处于更年轻的阶段。
