Sediment dynamics of turbidity maximum in Changjiang River mouth in dry season

Abstract

High-resolution current velocity and suspended sediment concentration (SSC) data were collected by using an Acoustic Doppler Current Profiler (ADCP) at two anchor stations and a cross-section in the South Channel of the Changjiang River mouth during meso and neap tides on Nov. 16, 2003. In addition, tidal cycle (13-hour) observation at two stations was carried out with traditional methods during the spring tide. Results indicated that resuspension occurred not only at the flood and ebb maximum, but also in the early phase of ebb in the meso and neap tide. When tidal current transited from high to ebb phase, current speed accelerated. Subsequently, fine-grained sediment with low critical threshold was resuspended and increased concentration. The river mouth area remained in siltation in the meso and neap tidal phase during the observation season, with calculated resuspension flux in the order of magnitude of 10 24 -10 27 kg?m 22 /s. Suspended sediment transport in the South Channel was dominated by freshwater discharge, but the Storks drift, vertical circulation and vertical shear effect due to tidal oscillation also played an important role in resuspension and associated sediment transport. In contrast, resuspension sediment flux in the spring tide was larger than that in meso and neap tide, especially at the ebb maximum and flood maximum. The present study revealed that intensive resuspension corresponded well with the larger current velocity during winter. In addition, the 'tidal pumping' effect and tidal gravity circulation were also vital for forming the turbidity maximum in the Changjiang River estuary.

Suspended sediment transport in the Deepwater Navigation Channel, Yangtze River Estuary, China, in the dry season 2009: 2. Numerical simulations

“…Considerable numerical modeling of the Yangtze River Estuary (YRE) has been carried out in recent years, most of which were focused on the hydrodynamics, such as salt water intrusion [e.g., Qiu et al ., ; Xue et al ., ], transport time [e.g., Wang et al ., ; Li et al ., ], and storm surges [e.g., Hu et al ., ]; little involved suspended sediment transport processes. On the other hand, most previous studies of the suspended sediment transport and the ETMs in the YRE have been based on field work [e.g., Su and Wang , ; Shen et al ., ; Shi et al ., ; Li and Zhang , ; Chen et al ., ; Shi et al ., ; Wu et al ., ; Gao et al ., ; Liu et al ., ; Wu et al ., ; Jiang et al ., ]. Shi [] used a one‐dimensional vertical model to study the fine suspended sediment distribution at the South Channel‐North Passage of the partially mixed YRE.…”

Sediment Transport Dynamics in Ports, Estuaries and Other Coastal Environments

“…41,[48][49][52][53][54][55][56][57][58][59]. However, since the completion of the Deep Navigation Channel in 2011, important changes to the local hydrodynamics, and thus to the transport of sediment, are expected.…”

“…However, since the completion of the Deep Navigation Channel in 2011, important changes to the local hydrodynamics, and thus to the transport of sediment, are expected. In addition, there is the effect of the fluvial sediment trap by the Three Gorges Dam, which caused a significant decrease to fluvial sediment load [59][60]. Although the reduction of fluvial sediment has been reported, the silting problem attracted attention because the estimate deposition of sediment in the navigation channel was over 100% of the original yearly average predicted value, i.e.…”

Response of the turbidity maximum zone to fluctuations in sediment discharge from river to estuary in the Changjiang Estuary (China)

“…The TMZ plays an important role in the transportation and deposition of fine sediments in estuarine areas and in shaping channel morphology. The TMZ also drives pollutant dispersal patterns by affecting the biogeochemical processing of heavy metals and organic material (Shen et al, 1992;Hollibaugh and Wong, 1999;Gao et al, 2008). As an example, the TMZ strongly affects ocean biological processes because it affects the depth of light penetration into the water column, a factor controlling primary production (May et al, 2003;de Swart et al, 2009).…”