Estimation of critical shear stress for erosion in the Changjiang Estuary: A synergy research of observation, GOCI sensing and modeling
Estimation of critical shear stress for erosion in the Changjiang Estuary: A synergy research of observation, GOCI sensing and modeling
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DOI：
10.1002/2015jc010992
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发表时间：
2015-12
影响因子：
--
通讯作者：
J. Ge;Fang Shen;Wenyun Guo;Changsheng Chen;P. Ding
中科院分区：
文献类型：
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作者：
J. Ge;Fang Shen;Wenyun Guo;Changsheng Chen;P. Ding
模拟具有空间变化的河床性质的高浊度地区的泥沙运动是具有挑战性的。本文采用多种方法相结合的综合策略，对长江口悬移质泥沙动力学过程中起主要作用的侵蚀临界剪应力进行了反演。利用地球同步轨道海洋彩色成像仪(GOCI)卫星资料每小时(每天8h)反演海面悬浮泥沙浓度时间序列，并结合高分辨率CE有限体积社区海洋模式(CE-FVCOM)的水动力模拟，估计粘土占优势的床层区域的近床临界剪应力(塑性指数 >； 7%)。采用塑性指数法确定现场临界剪应力的实验算法，对GOCI导出的临界剪应力进行了验证。采用这种新的临界切应力，泥沙输运模式显著改善了对CE大潮和小潮周期中SSC分布和空间变异性的模拟。结果表明，在大潮期间，河道和浅滩之间发生了显著的横向水交换，导致了整个水柱内更广泛的CE高SSC区域。
Simulating the sediment transport in a high-turbidity region with spatially varying bed properties is challenging. A comprehensive strategy that integrates multiple methods is applied here to retrieve the critical shear stress for erosion, which plays a major role in suspended sediment dynamics in the Changjiang Estuary (CE). Time-series of sea surface suspended sediment concentration (SSC) were retrieved from the Geostationary Ocean Color Imager (GOCI) satellite data at hourly intervals (for 8 h each day) and combined with hydrodynamic modeling of high-resolution CE Finite-Volume Community Ocean Model (CE-FVCOM) to estimate the near-bed critical shear stress in the clay-dominated bed region (plasticity index > 7%). An experimental algorithm to determine the in situ critical shear stress via the plasticity index method was also used to verify the GOCI-derived critical shear stress. Implemented with this new critical shear stress, the sediment transport model significantly improved the simulation of the distribution and spatial variability of the SSC during the spring and neap tidal cycles in the CE. The results suggest that a significant lateral water exchange between channels and shoals occurred during the spring flood tide, which led to a broader high-SSC area in the CE throughout the water column.