The transport and fate of riverine fine sediment exported to a semi-open system
(2016) 48th International Liege Colloquium on Ocean Dynamics Submesoscale Processes: Mechanisms, Implications and new Frontiers — Location: Liège (23.May.2016)
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- Abstract
- Understanding the transport and fate of suspended sediment exported by rivers is crucial for the management of sensitive marine ecosystems. Sediment transport and fate can vary considerably depending on the geophysical characteristics of the coastal environment. In this presentation, we focus on a setting in between “open” (uninterrupted coasts) and “semi-enclosed” (bays) coastal systems, namely a “semi-open” system of shallow coastal water with long (∼20 km) stretches of open coasts separated by capes and headlands. The case study is the large, seasonal, Burdekin River that discharges to a wide continental shelf containing headlands and shallow embayments adjacent to the Great Barrier Reef, Australia. Using a new 3D sediment model we developed and SLIM 3D, a Finite Element 3D model for coastal flows, we highlight the key processes of sediment transport for such a system. We validate successfully the model against available field data. Wind direction and speed during river floods largely control the dynamics and the fate of the fine sediment. Most (67% for 2007) of the riverine fine sediment load is deposited near the river mouth; the remaining sediment is transported further afield in a riverine freshwater plume; that sediment can reach sensitive marine ecosystems and should be a priority for management. During the rest of the year, when the river flow has ceased, wind-driven resuspension events redistribute the deposited sediment within embayments but generate negligible longshore transport. This study suggests that semi-open systems trap most of the riverine fine sediment, somewhat like semi-enclosed systems.
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Delandmeter, P., Lewis, S., Lambrechts, J., Legat, V., Deleersnijder, E., & Wolanski, E. (2016). The transport and fate of riverine fine sediment exported to a semi-open system. 48th International Liege Colloquium on Ocean Dynamics Submesoscale Processes: Mechanisms, Implications and new Frontiers, Liège. https://hdl.handle.net/2078.5/227220