Physical basis for quasi-universal relations describing bankfull hydraulic geometry of single-thread gravel bed rivers
Physical basis for quasi-universal relations describing bankfull hydraulic geometry of single-thread gravel bed rivers
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DOI：
10.1029/2006jf000549
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发表时间：
2007-12
影响因子：
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通讯作者：
G. Parker;P. Wilcock;C. Paola;W. Dietrich;J. Pitlick
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文献类型：
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作者：
G. Parker;P. Wilcock;C. Paola;W. Dietrich;J. Pitlick
[1]我们研究的关系，冲积，单线砾石河床河流的水力几何形状与可定义的bankfull几何形状。四个基线数据集确定了满岸几何形状的关系，即，作为平滩流量和床面中值泥沙粒径函数的平滩深度、平滩宽度和下游河道坡度。这些关系表现出相当程度的普遍性。这种普遍性不仅适用于用于确定形式的四个数据集，而且也适用于三个独立的数据集。我们从四个关系式来研究这种普适性的物理基础，其系数和指数可以从数据中反算出来：（1）Manning-Strickler型的河道阻力关系式，（2）用满岸Shields数与临界Shields数之比表示的河道形成关系式，（3）临界Shields数与无量纲流量的关系式，以及（4）“砾石产率”关系式，该关系式规定了平滩流量下砾石输运率（估计值）与平滩流量和砾石粒径的函数关系。我们使用这些潜在的关系，以探讨为什么无量纲的银行的关系是唯一的准普遍性和量化的程度偏离普遍性可以预期。这里提出的分析代表了一种替代极值公式来预测水力几何形状。
[1] We examine relations for hydraulic geometry of alluvial, single-thread gravel bed rivers with definable bankfull geometries. Four baseline data sets determine relations for bankfull geometry, i.e., bankfull depth, bankfull width, and down-channel slope as functions of bankfull discharge and bed surface median sediment size. These relations show a considerable degree of universality. This universality applies not only within the four sets used to determine the forms but also to three independent data sets as well. We study the physical basis for this universality in terms of four relations, the coefficients and exponents of which can be back calculated from the data: (1) a Manning-Strickler-type relation for channel resistance, (2) a channel-forming relation expressed in terms of the ratio of bankfull Shields number to critical Shields number, (3) a relation for critical Shields number as a function of dimensionless discharge, and (4) a “gravel yield” relation specifying the (estimated) gravel transport rate at bankfull flow as a function of bankfull discharge and gravel size. We use these underlying relations to explore why the dimensionless bankfull relations are only quasi-universal and to quantify the degree to which deviation from universality can be expected. The analysis presented here represents an alternative to extremal formulations to predict hydraulic geometry.