This paper examines particle settling dynamics in a tidally-influenced delta, including observations of convective settling, strongly modulated by seasonal discharge and tidal cycles. Long time series of Acoustic Doppler Current Profiler backscatter, a proxy for suspended sediment concentration in the water column, current and sediment accumulation measurements from the slope of the Fraser River delta show variability of sedimentary processes over timescales from semi-diurnal to annual. Acoustic Doppler Current Profiler backscatter shows a lagged response to river discharge and strong diurnal/semi-diurnal variability. Most of the tidal cycle is characterized by a buoyant effluent plume. During the ebbing phase of diurnal major tides, discrete settling events are observed extending through the entire water column. The pulse-like nature of these events is the result of downward plunging fingers characteristic of convective settling, similar to those observed in laboratory flume experiments, and appear to be initiated at the interface between the surface buoyant plume and the underlying ambient water. Currents show strong variability in a three-layer water column. The surface plume shows offshore and southward directed transport of sediments. The remaining water column is influenced by tidal flows, but near surface and intermediate water-depth currents are out of phase by several hours, indicating a stratification of the basin water and decoupled propagation of surface and internal tides. This phase lag is unlikely to cause discernible facies changes, but may have implications for basin-fill patterns in restricted basins with strong tidal range. The results of this work will help to better understand river mouth sedimentation processes and dispersal patterns in other modern deltas and in the geological record.

中文翻译：

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受潮汐影响的三角洲口的沉积过程：来自加拿大弗雷泽三角洲海底观测站测量的新见解

本文研究了受潮汐影响的三角洲中的粒子沉降动力学，包括对受季节性排放和潮汐循环强烈调节的对流沉降的观察。声学多普勒海流剖面仪反向散射的长时间序列，代表水体中悬浮泥沙浓度，来自弗雷泽河三角洲斜坡的海流和沉积物积累测量显示沉积过程在从半日到一年的时间尺度上的变化。声学多普勒电流剖面仪反向散射显示对河流流量和强烈的昼夜/半昼夜变化的滞后响应。大多数潮汐循环的特点是有漂浮的污水羽流。在昼夜大潮的退潮阶段，观察到离散的沉降事件延伸到整个水体。这些事件的脉冲状性质是对流沉降的特征向下坠落的结果，类似于实验室水槽实验中观察到的那些，并且似乎是在表面浮力羽流和下面的环境水之间的界面处开始的。水流在三层水柱中表现出强烈的可变性。地表羽流显示了沉积物的近海和向南输送。剩余的水柱受潮汐流的影响，但近地表和中间水深的水流在几个小时内异相，表明流域水分层，表层和内部潮汐的传播解耦。这种相位滞后不太可能导致明显的相变化，但可能对潮差强的受限盆地中的盆地填充模式产生影响。