Morphologic signatures of autogenic waterfalls: A case study in the San Gabriel Mountains, California
Morphologic signatures of autogenic waterfalls: A case study in the San Gabriel Mountains, California
复制标题
自生瀑布的形态特征：加利福尼亚州圣盖博山脉的案例研究
DOI：
10.1130/g49320.1
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发表时间：
2021
期刊：
影响因子：
5.8
通讯作者：
Scheingross, Joel S.
中科院分区：
文献类型：
--
作者：
Groh, Erika L.;Scheingross, Joel S.
瀑布的形成是由于河流基准面的外部扰动、岩性异质性和内部反馈（即自生动力学）。虽然由岩性异质性和外部扰动形成的瀑布有据可查，但缺乏识别自生瀑布的标准，从而限制了评估自生瀑布对景观演变影响的能力。我们建议，自生瀑布演变从基岩床被称为循环步骤，因此形成一系列的步骤，间距和高度设置主要由通道坡度。我们确定了360个瀑布分裂之间的瞬态和稳态部分的圣加布里埃尔山脉在加州，美国。结果表明，虽然瀑布在瞬态和稳态景观中的空间分布不同，但两种景观中的瀑布都倾向于在大于3%的坡度处形成，与Froude超临界流的开始相一致，两种景观中瀑布的高度与间距比随坡度的增加而增加，与循环台阶理论和水槽实验一致。我们认为，在未冰川山脉与相对均匀的岩石强度，个别瀑布主要是自生的起源，而瀑布的空间分布可能是由外部扰动。
Waterfalls can form due to external perturbation of river base level, lithologic heterogeneity, and internal feedbacks (ie, autogenic dynamics). While waterfalls formed by lithologic heterogeneity and external perturbation are well documented, there is a lack of criteria with which to identify autogenic waterfalls, thereby limiting the ability to assess the influence of autogenic waterfalls on landscape evolution. We propose that autogenic waterfalls evolve from bedrock bedforms known as cyclic steps and therefore form as a series of steps with spacing and height set primarily by channel slope. We identified 360 waterfalls split between a transient and steady-state portion of the San Gabriel Mountains in California, USA. Our results show that while waterfalls have different spatial distributions in the transient and steady-state landscapes, waterfalls in both landscapes tend to form at slopes> 3%, coinciding with the onset of Froude supercritical flow, and the waterfall height to spacing ratio in both landscapes increases with slope, consistent with cyclic step theory and flume experiments. We suggest that in unglaciated mountain ranges with relatively uniform rock strength, individual waterfalls are predominately autogenic in origin, while the spatial distribution of waterfalls may be set by external perturbations.