Fluvial sediment pulses are associated with a sudden and major increase in sediment supply to riverine environments. Their occurrence can be triggered by natural or anthropogenic factors or processes, including landslides, debris flows from tributaries, volcanic eruptions, dam removals, and mining‐related activities. To predict their propagation, decoupled (clear‐water) models are commonly used, despite shortcomings identified when simulating the initial propagation phase and the existence of coupled (sediment‐laden) models. Herein, a framework for improving the accuracy of modeling efforts that simulate fluvial sediment pulse propagation dynamics is presented. The framework is centered on a physics‐based criterion formed by a dimensionless parameter ξ and its threshold condition ξ_cr. Comparison with laboratory and field studies shows that ξ indicates the relative importance of the terms neglected in decoupled models and that its threshold condition ξ_cr effectively sets an upper limit for their application. Results show that decoupled models are inaccurate when ξ > ξ_cr but become sufficient when ξ < ξ_cr. When applied to well‐monitored fluvial sediment pulses, the framework quantifies the two‐phase propagation dynamics observed in the field, showing an initial phase characterized by ξ > ξ_cr and a subsequent phase characterized by ξ ≤ ξ_cr. Overall, the framework provides a physics‐based quantitative approach that addresses the limitations of decoupled models by setting an upper limit for their range of validity.

中文翻译：

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河床泥沙脉冲传播过程中的水动力过程建模：基于物理学的框架

河道沉积物冲动与向河流环境的沉积物供应突然大量增加有关。它们的发生可能是由自然或人为因素或过程触发的，包括滑坡，支流的泥石流，火山喷发，大坝拆除以及与采矿有关的活动。为了预测它们的传播，尽管在模拟初始传播阶段时发现了缺点，并且存在耦合（含泥沙）模型，但通常使用解耦（清水）模型。在此，提出了一种用于提高模拟河流泥沙脉冲传播动力学模拟工作的准确性的框架。该框架的中心在通过无量纲参数形成一个基于物理学的标准ξ和其阈值条件ξ _CR。与实验室和现场研究显示比较是ξ表示退耦模型忽略了条款的相对重要性，以及它的阈值条件ξ _CR有效地设置了其应用的上限。结果表明，解耦模型是不准确的，当ξ > ξ _CR反而变得足够的，当ξ < ξ _CR。当施加到良好监测河流沉积物脉冲，该框架量化在该领域中观察到的两相传播动力学，示出了初始相位，其特征在于ξ > ξ _CR和随后的相位，其特征在于ξ≤ ξ _CR。总体而言，该框架提供了一种基于物理的定量方法，该方法通过设置有效性模型的上限来解决解耦模型的局限性。