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Deltas are at the transition between fluvial and marine sedimentary environments where sediment density flows are often triggered during high river discharge events, forming submarine channels and sediment waves. On wave‐influenced deltas, longshore currents are particularly efficient at transporting sediment alongshore, reducing the likelihood of sediment density flows from occurring at river mouths. This study describes four deltaic sedimentary systems at different stages of their evolution on a formerly glaciated continental inner shelf of eastern Canada in order to better understand the distribution of sediment density flows on wave‐influenced deltas. Three types of settings are recognized as being prone to sediment density flows: (i) in the early stages of wave‐influence and on large deltas, converging longshore currents can lead to offshelf sediment transport; (ii) on wave‐influenced to wave‐dominated deltas, a sandy spit can re‐route the river mouth and sediment density flows form where the spit intersects the delta lip; (iii) in advanced stages of wave‐dominated deltas and during their demise, rocky headlands are exposed and can intersect the slope, where off‐shelf sediment transport occurs. These types of sediment density flows were all characterized by debris flows or surge‐type turbidity currents which have limited offshore run‐out. More rarely, hyperpycnal flows form at the river mouths, especially where the river incises glaciomarine clays prone to landsliding in the river, which increases fine‐grained fluvial suspended sediment concentration. Overall, these results highlight the predominance of fluvial‐dominated deltas during a phase of relative sea‐level fall combined with high sediment supply. However, as soon as sediment supply diminishes, wave action remobilizes sediment alongshore modifying the distribution and types of sediment density flows occurring on wave‐influenced deltas. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The article presents a study on suspended sediment delivery processes conducted in the Cape Bounty Arctic Watershed at the Canadian High Arctic from 2004-2006. The study used different methodologies including precipitation and air temperature measurement, sediment transport data collection, and grain size sampling and analysis. Results show that sediment characteristics in High Arctic catchments exhibit complex relationships with channel snowpack and nonlinear responses to flow conditions.