Wind-enhanced resuspension in the shallow waters of South San Francisco Bay: Mechanisms and potential implications for cohesive sediment transport
Wind-enhanced resuspension in the shallow waters of South San Francisco Bay: Mechanisms and potential implications for cohesive sediment transport
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DOI：
10.1029/2010jc006172
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发表时间：
2010-11
影响因子：
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通讯作者：
A. Brand;J. Lacy;Kevin Hsu;D. Hoover;Steve Gladding;M. Stacey
中科院分区：
文献类型：
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作者：
A. Brand;J. Lacy;Kevin Hsu;D. Hoover;Steve Gladding;M. Stacey
[1]我们调查了南旧金山湾浅滩沉积物动力学的驱动力。沿一条垂直于一条14米深的航道的线路部署了两个站点，距离航道中央分别为1000米和2000米。台站深度分别比平均低水位低2.59m和2.19m。我们使用声学多普勒测速仪同时测定水流速度、湍流、泥沙浓度和通量。最大剪切速度在距离航道较远(近岸)的测站为0.015 m S−1，在靠近航道的测站为0.02m S−1。峰值波引起的切变速度在两个台站都超过了0.015米S−1。最大含沙量在平静期(均方根波高0.10g m−2 S−1)约为30gm−3，距河床以上0.36m。在航道附近，风浪再悬浮引起的泥沙浓度和垂直通量持续较低(最大浓度约为50g m−3，最大通量约为0.04g m−2 S−1)。大多数再悬浮事件发生在低潮期间跟随波浪事件的洪潮期间。虽然在退潮时波浪运动能够将泥沙重新悬浮到波浪边界层中，但观测到的泥沙通量的大幅增加是由于风浪和潮流的非线性相互作用。
[1] We investigated the driving forces of sediment dynamics at the shoals in South San Francisco Bay. Two stations were deployed along a line perpendicular to a 14 m deep channel, 1000 and 2000 m from the middle of the channel. Station depths were 2.59 and 2.19 m below mean lower low water, respectively. We used acoustic Doppler velocimeters for the simultaneous determination of current velocities, turbulence, sediment concentration and fluxes. Maximum current shear velocities were 0.015 m s−1 at the station further from the channel (closer to the shore) and 0.02 m s−1 at the station closer to the channel. Peak wave-induced shear velocities exceeded 0.015 m s−1 at both stations. Maximum sediment concentrations were around 30 g m−3 during calm periods (root mean square wave height 0.10 g m−2 s−1) at the station further from the channel 0.36 m above the bed. Closer to the channel, sediment concentrations and vertical fluxes due to wind wave resuspension were persistently lower (maximum concentrations around 50 g m−3 and maximum fluxes around 0.04 g m−2 s−1). Most resuspension events occurred during flood tides that followed wave events during low water. Although wave motions are able to resuspend sediment into the wave boundary layer at low tide, the observed large increases in sediment fluxes are due to the nonlinear interaction of wind waves and the tidal currents.