Meandering river floodplains often contain intermittently flooded complex channel networks. Many questions remain as to the pervasiveness, function, and evolution of these floodplain channels. In this present work, we analyzed size‐specific sediment transport potential and assessed whether the channelized floodplain of the meandering East Fork White River near Seymour, Indiana is on a net erosional or depositional trajectory. We applied a two‐dimensional hydrodynamic model and used simulated model results to estimate the largest sediment size that can be moved in suspension and as bedload at various flows for grain size classes between 4 µm and 64 mm. We developed a probabilistic method that integrates the largest sediment size that can be moved at various flows to compute an effective grain size, which we compared to measured field data. Results show that the river is capable of supplying sand to the floodplain and these floodplain channels can transport sand in suspension and gravel as bedload. This suggests that sediment supplied from the river could be transported as bedload in floodplain channels. These floodplain channels are supply limited under the current hydrologic regime and the grain size distribution of the bed surface is set by the flow conditions; thus, these floodplain channels are net erosional. Finally, our proposed method of probabilistically integrating the largest sediment size that can be moved at various flows can be used to predict the upper end of the grain size distribution in suspension and in bed material, which is applicable to floodplains as well as coastal areas.

中文翻译：

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水力连接的河流和漫滩通道系统中的泥沙输送潜力

蜿蜒的河滩通常包含间歇性淹没的复杂河道网络。关于这些漫滩渠道的普遍性，功能和演变，仍然存在许多问题。在本工作中，我们分析了特定大小的沉积物运移潜力，并评估了印第安纳州西摩附近蜿蜒的东福克怀特河的河道漫滩是否处于净侵蚀或沉积轨迹。我们应用了二维流体动力学模型，并使用模拟的模型结果来估计在4 µm至64 mm粒度等级下，在各种流量下的悬浮液和床荷中可移动的最大沉积物尺寸。我们开发了一种概率方法，该方法整合了可以在各种流量下移动的最大沉积物尺寸，以计算有效晶粒尺寸，并将其与实测数据进行了比较。结果表明，河流能够为泛滥平原提供沙土，这些漫滩河道可以将悬浮物和砾石中的沙质作为河床来运输。这表明从河流供应的沉积物可以作为河床在洪泛区河道中运输。在当前的水文条件下，这些洪泛区通道的供水受到限制，而河床表面的粒度分布则由流动条件决定。因此，这些漫滩渠道是净侵蚀的。最后，我们提出的概率积分方法可以概率性地集成可以在各种流量下移动的最大沉积物尺寸，该方法可用于预测悬浮液和床料中颗粒尺寸分布的上限，这适用于洪泛区和沿海地区。