Quantitative relationships between river and channel-belt planform patterns
Quantitative relationships between river and channel-belt planform patterns
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DOI：
10.1130/g49935.1
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发表时间：
2022-06-13
期刊：
影响因子：
5.8
通讯作者：
Goudge, Timothy A.
中科院分区：
文献类型：
--
作者：
Dong, Tian Y.;Goudge, Timothy A.
河道平面形态源于河流泥沙运动和水流的内部动力，并受河谷限制等外部控制因素的影响。了解这些河道模式是否被保存在岩石记录中，对于我们限制过去环境条件的能力具有至关重要的影响。河流被保存为河道带，这是沉积记录中最普遍和最容易获得的部分之一，但河流和河道带平面形态之间的关系仍未量化。我们分析了全球30个系统的河流和航道带的平面形态。河道类型的分类使用了基于图论的指标--编织指数(EBI)，该指数通过考虑水和泥沙流量的分配来量化河道的数量。结果表明，在按河道大小归一化后，河道带宽度、波长、振幅和曲率均随河道数(EBI)的增加而减小。单河道河流的活流量只占河道带的1%，而多河道河流的活流量可占河道带的50%。此外，我们发现，通道模式位于通道编号的连续体上。我们的发现对河流与滩地相互作用、滩地沉积物的储存时间尺度和古环境重建的研究具有重要意义。
Channel planform patterns arise from internal dynamics of sediment transport and fluid flow in rivers and are affected by external controls such as valley confinement. Understanding whether these channel patterns are preserved in the rock record has critical implications for our ability to constrain past environmental conditions. Rivers are preserved as channel belts, which are one of the most ubiquitous and accessible parts of the sedimentary record, yet the relationship between river and channel-belt planform patterns remains unquantified. We analyzed planform patterns of rivers and channel belts from 30 systems globally. Channel patterns were classified using a graph theory-based metric, the Entropic Braided Index (eBI), which quantifies the number of river channels by considering the partitioning of water and sediment discharge. We find that, after normalizing by river size, channel-belt width and wavelength, amplitude, and curvature of the belt edges decrease with increasing river channel number (eBI). Active flow in single-channel rivers occupies as little as 1% of the channel belt, while in multichannel rivers it can occupy >50% of the channel belt. Moreover, we find that channel patterns lie along a continuum of channel numbers. Our findings have implications for studies on river and floodplain interaction, storage timescales of floodplain sediment, and paleoenvironmental reconstruction.