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Physics of estuaries and coastal seas
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Differentiating the effects of advection and resuspension on suspended sediment concentrations in a turbid estuary
P-P1-07-S
Yuan Li* , Ministry of Education Key Laboratory for Coast and Island Development, Nanjing University
Jianjun Jia, State Key Laboratory of Estuarine and Coastal Research, East China Normal University
Qingguang Zhu, Department of Environmental Sciences, University of Virginia
Peng Cheng, State Key Laboratory of Marine Environment Science, College of Ocean and Earth Sciences, Xiamen University
Shu Gao, State Key Laboratory of Estuarine and Coastal Research, East China Normal University
Ya Ping Wang, State Key Laboratory of Estuarine and Coastal Research, East China Normal University
Presenter Email: yuanlee@smail.nju.edu.cn |
| Suspended sediment concentration (SSC) has a significant impact on the estuarine environment and its morphological evolution. At any given location, variability in depth-averaged SSC is controlled by a combination of two processes: horizontal advection and local resuspension. In this study, we investigate the sediment dynamics at three anchored monitoring stations close to the maximum turbidity zone of the Changjiang Estuary, and developed a box model to differentiate the effects of advection and resuspension. Further, settling velocities were estimated using the ADV Reynolds flux method. We found that predicted changes in advection- and resuspension-induced SSCs were consistent with the bed shear stress and erosion/accretion observations. The combination of observed bed erosion/accretion changes and the predicted advection-induced SSCs indicates that the advective transport of suspended sediment is an important process in accelerating persistent erosion at the observation stations. Although SSC variations due to advection and resuspension are of similar magnitudes, our model results indicate that if resuspension dominates, then the resuspension-induced component can reach up to twice the magnitude of the advection-induced component. We conclude that the box model is a valuable tool for evaluating subaqueous delta erosion/accretion in response to sediment reduction caused by upstream dam construction and climate change in recent decades. |
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