Across-shelf sediment transport: Interactions between suspended sediment and bed sediment
Across-shelf sediment transport: Interactions between suspended sediment and bed sediment
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DOI：
10.1029/2000jc000634
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发表时间：
2002-01-15
影响因子：
3.6
通讯作者：
Wiberg, P
中科院分区：
文献类型：
--
作者：
Harris, CK;Wiberg, P
[1]我们使用一个二维的，随时间变化的沉积物输运模型，以量化跨货架运输，沉积和排序在波浪驱动的再悬浮事件的特点，那些主导沉积物输运在许多大陆架。随着水深的增加，波浪轨道速度减小，由此产生的河床剪切应力的跨陆架梯度有利于沉积物的净离岸运输。在宽阔平坦的大陆架上（坡度约为0.1%），这些梯度很低，海底改造的深度主要取决于海底剪切应力和当地沉积物的可利用性。然而，在狭窄、陡峭的陆架（坡度近似于0.5%）上，底应力梯度产生了显著的跨陆架悬浮泥沙通量梯度，从而形成净侵蚀和沉积区域。虽然波浪的大小通常决定了沉积物可以重新悬浮的水深，但狭窄陆架上的侵蚀和沉积模式对波浪能量的跨陆架梯度、非局部沉积物可用性以及跨陆架电流的方向和大小很敏感。在充满活力的波，跨陆架的悬浮泥沙通量的发散，可以创建一个粗糙的，侵蚀区的内架，毗邻一个地区的细颗粒泥沙沉积的中间到外部的货架。然而，如果水流强烈地向岸流动，通量发散会导致整个大陆架的侵蚀。
[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 similar to0.1%), 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 similar to0.5%), 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.