Floc size, density, and settling velocity were investigated in the Connecticut River estuary over 3 years spanning varying fluvial discharge regimes to determine the role of cohesive suspended particle characteristics in the sediment-transport patterns of an energetic estuary. Concurrent measurements of flow, bed stress, salinity, and suspended sediment concentration were used to identify primary controls on floc size variability. Water discharge ranged from 202 to 910 m³/s between the three sampling campaigns, and the timing of major sediment-discharge events preceding measurement periods from 23 to 162 days. Two distinct particle populations were observed under high and low sediment-discharge regimes. With abundant fluvial sediment input, flocculation occurred resulting in large, loosely packed flocs dominating the suspended signal (median sizes of 194–209 μm; median excess densities of 13–17 kg/m³). Following an extended period of low sediment discharge, small, dense aggregates resuspended from the bed were observed throughout the water column (median size of 171 μm and excess density of 60 kg/m³). The timing and partial decoupling of water and sediment discharge led to inter-annual patterns of particle packaging controlled by fresh sediment supply. When the estuary is “charged” with sediment following high discharge events, the characteristic large, less dense flocs with lower settling velocities primarily bypass the estuary. The similar disaggregated grain size distribution of the suspended material of the two regimes suggests the same source sediment is reintroduced to the estuary with the intrusion of the salt wedge, which extends farther up-estuary during low-discharge regimes. The fines repackaged as dense aggregates ultimately supply the channel margins and off-channel coves currently experiencing sediment accumulation.

中文翻译：

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高能河口中粘性颗粒特征的变异性：絮凝物与聚集体

在3年的时间里，在康涅狄格河河口调查了絮凝物的大小，密度和沉降速度，这些河水跨越了不同的河流排放方式，以确定粘性悬浮颗粒特征在高能河口输沙模式中的作用。同时测量流量，床应力，盐度和悬浮沉积物浓度，以确定絮凝物大小变异性的主要对照。排水量从202到910 m ³/ s在三个采样活动之间，以及在测量期23天到162天之前发生主要沉积物排放事件的时间。在高和低排沙量下，观察到两个不同的粒子群。随着大量河流沉积物的输入，发生了絮凝，导致了大的，松散堆积的絮凝物主导了悬浮信号（中值大小为194–209μm；中值超密度为13–17 kg / m ³）。在长时间的低沉积物排放之后，在整个水柱中观察到了小而致密的聚集物从床中悬浮（中值尺寸为171μm，过密度为60 kg / m ^3））。水和泥沙排放的时间安排和部分解耦导致了由新鲜泥沙供应控制的颗粒包装的年际格局。当高排放事件使河口被沉积物“充填”时，具有较低沉降速度的特征性较大，密度较小的絮凝物主要绕过河口。两种方案中悬浮物的相似的分解粒度分布表明，随着盐楔的侵入，相同的源沉积物被重新引入河口，在低排放方案中盐楔向上游延伸。重新包装为致密骨料的细粉最终提供了河道边缘和目前正在经历沉积物堆积的河道外海湾。