In 2012, using multibeam water column imaging and a rapidly dipping towed optical backscatter probe, the evolution of a descending suspended sediment plume below the overlying river plume was monitored on an hourly basis. Towards low water, that descending plume was seen to occasionally feed a near seabed higher suspended sediment layer. On the development of this layer, the water column imaging revealed a thin basal flow that lasted about an hour and corresponded directly with the period of migration of the channel floor bedforms. Delta-lip failures are associated with the upslope end of about half of the bedform trains suggesting an alternate initiating mechanism.
