Estuarine sediment dynamics are a consequence of various forcings (barotropic, estuarine circulation, and fluvial) that vary in space and time. Here, we present a study examining sediment dynamics in a narrow microtidal estuary, the Lower Passaic River in New Jersey, USA. The analysis incorporates measurements of suspended sediments, morphological change, sediment erodibility, and a numerical hydrodynamic model. The former two datasets are used to develop an understanding of sediment dynamics over the full range of hydrologic conditions, and the latter two datasets are used to interpret the behavior of the system. Subsequently, a conceptual picture is developed, one that classifies the morphological status of the system at any given time into three regimes dependent on river flow—regime I includes conditions when the system is importing sediments, regime II includes conditions when the system is exporting sediments by flushing a thin easily erodible surficial stratum termed the fluff layer, and regime III includes conditions when the system is exporting sediments by scouring more consolidated strata underneath the fluff layer. Regime III is relevant for the long-term morphodynamic equilibrium of the estuary by providing a mechanism that erodes and exports sediment accumulated under regime I conditions. Consequently, sediment dynamics depend not only on short time-scale processes such as the instantaneous river flow rate, but also on the time-history of river flow, and the long-term morphological progression of the system. These regimes represent a conceptualization of estuarine sediment transport dynamics and can be useful in the development of effective estuarine sediment management strategies.

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狭窄微潮河口的泥沙动力学和输沙方式

河口沉积物动力是时空变化的各种强迫作用（正压，河口环流和河流）的结果。在这里，我们提出一项研究，研究狭窄的潮汐河口（美国新泽西州的下Passaic河）中的沉积物动力学。该分析包括对悬浮沉积物，形态变化，沉积物易蚀性和数值流体动力学模型的测量。前两个数据集用于发展对整个水文条件范围内沉积物动力学的理解，后两个数据集用于解释系统的行为。随后，提出了一个概念图，该图将系统在任何给定时间的形态状态分为三种取决于河流流量的状态，第一类包括系统输入沉积物时的条件，方法II包括系统通过冲洗薄薄的易剥蚀表皮层（称为绒毛层）来输出沉积物的条件，方案III包括系统通过冲洗绒毛层下的更固结层来输出沉积物的条件。区域III通过提供一种侵蚀和输出在区域I条件下积累的沉积物的机制，与河口的长期形态动力平衡相关。因此，沉积物动力学不仅取决于短时尺度的过程，例如瞬时河​​流量，还取决于河水的时间历史以及系统的长期形态学进程。