Can Bankfull Discharge and Bankfull Channel Characteristics of an Alluvial Meandering River be Cospecified From a Flow Duration Curve?
Can Bankfull Discharge and Bankfull Channel Characteristics of an Alluvial Meandering River be Cospecified From a Flow Duration Curve?
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DOI：
10.1029/2018jf004971
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发表时间：
2019-10
期刊：
影响因子：
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通讯作者：
K. Naito;G. Parker
中科院分区：
文献类型：
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作者：
K. Naito;G. Parker
我们提出了一个简单的建模框架，用于共同确定冲积曲流河的满岸流量和相应的满岸河道几何形状（宽度、深度和纵向河道坡度）。我们特别考虑了一条沙床河流，其漫滩上覆盖着富含泥浆的层。我们询问河流所承受的广泛水流如何导致建立满岸流量和相关满岸几何形状的具体值。在这里，我们提供了基于物理的满岸流量预测器，超出了 1.5 年洪水流量的简单假设。我们使用基于物理的河道和洪泛区过程子模型来实现这一点。我们表明，满岸流量和满岸几何形状的建立是由于（i）河漫滩沉积造成的漫滩垂直积聚，（ii）内岸和外切岸的迁移，（iii）由于河道横向移动导致漫滩沉积物的净去除和平均漫滩高度的降低，以及（iv）河道内下游河床物质迁移的结果。流动持续时间曲线用于量化这些过程的影响，并考虑流动变化。我们的模型捕捉了满岸流量、深度、宽度和下游坡度向特定流量持续时间曲线和流域特征达到平衡的时空演变。我们的新框架可用于评估河流对沉积物供应或流量持续时间曲线变化的长期响应。针对美国德克萨斯州三一河的案例提出了模型实现，以演示模型的使用及其行为。
We present a simple modeling framework for the codetermination of bankfull discharge and corresponding bankfull channel geometry (width, depth, and longitudinal channel slope) of an alluvial meandering river. We specifically consider a sand‐bed river whose floodplain is capped by a mud‐rich layer. We inquire as to how the wide spectrum of flows to which the river is subjected leads to the establishment of specific values for bankfull discharge and associated bankfull geometry. Here we provide a physically based predictor of bankfull discharge that goes beyond the simple assumption of the 1.5‐year flood discharge. We do this using physics‐based submodels for channel and floodplain processes. We show that bankfull discharge and bankfull geometry are established as a result of (i) floodplain vertical accretion due to overbank deposition, (ii) migration of the inner bank and outer cut bank, (iii) net removal of floodplain sediment and reduction in average floodplain height due to lateral channel shift, and (iv) in‐channel downstream bed material transport. The flow duration curve is employed to quantify the effect of these processes, as well as to account for flow variability. Our model captures the spatiotemporal evolution of bankfull discharge, depth, width, and down‐channel slope toward equilibrium for specified flow duration curve and watershed characteristics. Our new framework can be used for assessing long‐term river response to change in sediment supply or flow duration curve. A model implementation is presented for the case of the Trinity River, TX, USA, to demonstrate the use of the model and its behavior.