JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. C1, 10.1029/2000JC000634, 2002
Across-shelf sediment transport: Interactions between suspended sediment and bed sediment
Department of Environmental Sciences, University of Virginia,
Charlottesville, Virginia, USA
Now at Virginia Institute of Marine Science,
Gloucester Point, Virginia, USA
Department of Environmental Sciences, University of Virginia,
Charlottesville, Virginia, USA
Abstract
[1] We use a two-dimensional, time-dependent sediment-transport model to quantify across-shelf transport, deposition, and sorting during wave-driven resuspension events characteristic of those that dominate sediment transport on many continental shelves. Decreases in wave-orbital velocities as water depth increases, and the resulting cross-shelf gradient in bed shear stress favor a net offshore transport of sediment. On wide, flat shelves (slopes ~0.1%), these gradients are low, and the depth to which the seabed is reworked depends mainly on bottom shear stress and local sediment availability. On narrow, steep shelves (slopes ~0.5%), however, the gradient in bottom stress generates significant cross-shelf suspended sediment flux gradients that create regions of net erosion and deposition. While the magnitude of waves generally determines the water depth to which sediment can be resuspended, erosional and depositional patterns on narrow shelves are sensitive to cross-shelf gradients in wave energy, nonlocal sediment availability, and the direction and magnitude of the cross-shelf current. During energetic waves, cross-shelf divergence of suspended sediment flux can create a coarsened, erosional area on the inner shelf that abuts a region of fine-grained sediment deposition on the mid-to-outer shelf. If currents are strongly shoreward, however, flux divergence leads to erosion over the entire shelf.
Received 12 September 2000; revised 9 July 2001; accepted 13 July 2001; published 30 January 2002.
Index Terms: 4211 Oceanography: General: Benthic boundary layers; 3022 Marine Geology and Geophysics: Marine sediments-processes and transport; 4255 Oceanography: General: Numerical modeling; 4219 Oceanography: General: Continental shelf processes.
Citation: , Across-shelf sediment transport: Interactions between suspended sediment and bed sediment, J. Geophys. Res., 107(C1), 10.1029/2000JC000634, 2002.