Dynamics of the turbidity maximum in the Changjiang Estuary, China
Shi, Z. (2002). Dynamics of the turbidity maximum in the Changjiang Estuary, China, in: Winterwerp, J.C. et al. (Ed.) Fine sediment dynamics in the marine environment. Proceedings in Marine Science, 5: pp. 655-669 In: Winterwerp, J.C.; Kranenburg, C. (Ed.) (2002). Fine sediment dynamics in the marine environment. Proceedings in Marine Science, 5. Elsevier: Amsterdam. ISBN 0-444-51136-9. XV, 713 pp., more In: Proceedings in Marine Science. Elsevier: New York. ISSN 1568-2692; e-ISSN 2352-2860, more |  |
| Keyword | | | Author keywords | cohesive sediment transport; turbidity maximum; the Changjiang Estuary |
| Abstract | Observations have shown that the Changjiang Estuary has a turbidity maximum zone. Vertical profiles of horizontal current speed/direction, salinity and cohesive suspended sediment concentration were measured in the Changjiang Estuary. Cohesive suspended sediment concentrations were also acoustically monitored. A two-dimensional depth-integrated horizontal (2DH) numerical model was developed to predict tidal currents and cohesive sediment transport processes within the turbidity maximum at the South Channel of the Changjiang Estuary. The Alternating Direction Implicit (A.D.I.) scheme was used to solve the governing equations. Those observational and modeled data were analyzed for the mechanisms for the formation of the turbidity maximum and intratidal variations in cohesive sediment transport processes, with special emphasis on near-bed processes in the Changjiang Estuary.Four dominant mechanisms responsible for the formation of the turbidity maximum are 1) tidal asymmetry and 2) gravitational circulation at the seaward end of the North Passage, 3) near-bed periodic tidal resuspension at the landward end of the North Passage, and 4) turbulence suppression by cohesive suspension/salinity stratification at the North Passage in the Changjiang Estuary. In addition, three dominant cohesive sediment transport processes were acoustically identified within the near-bed high concentrated mud suspensions: 1) long-period resuspension events superimposed on 2) short period bursts close to the cohesive mud bed; and 3) re-entrainment of the near-bed high concentrated mud suspensions by tidal shear flow. |
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