Flow and sediment transport on a tidal salt marsh surface
Flow and sediment transport on a tidal salt marsh surface
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DOI：
10.1006/ecss.2000.0548
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发表时间：
2000-03-01
影响因子：
2.8
通讯作者：
Milligan, TG
中科院分区：
文献类型：
--
作者：
Christiansen, T;Wiberg, PL;Milligan, TG
通过一系列泥沙浓度、流速、湍流、水面高程、沼泽地形和沉积在沼泽表面沉积物的粒度分布的测量，描述了控制弗吉尼亚州大西洋沿岸中盐沼表面矿物沉积的物理过程。由于数据集的综合性，可以评估沼泽表面沉积的时间和空间变异性、不同幅度潮汐之间沉积过程的变异性以及控制这一潮汐沼泽沉积的具体过程。通过三种不同类型的测量，发现在潮汐上升时，沼泽表面发生了泥沙淤积，潮汐高程从几乎不淹没小溪岸边的潮汐到大潮，而且泥沙在初始淤积后不被潮流再动员。泥沙淤积主要是因为悬浮物中的细小泥沙形成了絮状物。潮沟8m范围内沉积物的无机粒度分布分析表明，70%-80%的沉积物是以絮凝形式沉积的。其余的(大于20微米的颗粒)以单个颗粒的形式沉积。沼泽腹地距潮沟25m处，以单颗粒沉积为主。沼泽植被冠层内湍流程度的降低也促进了颗粒的沉降。控制泥沙淤积的过程并不因潮汐而异。然而，悬浮泥沙。河岸附近的浓度随着潮汐幅度的增加而增加，因此在涨潮时促进了更高的沉积速率。(C)2000年学术出版社。
The physical processes that control mineral sediment deposition on a mesotidal salt marsh surface on the Atlantic Coast of Virginia were characterized through a series of measurements of sediment concentration, flow velocity, turbulence, water surface elevation, marsh topography and particle size distributions of sediment deposited on the marsh surface. The comprehensive nature of the data set allowed assessment of the temporal and spatial variability in marsh surface deposition, the variability in depositional processes among tides of different amplitudes, as well as the specific processes that control deposition on this tidal marsh. Through three different types of measurements, if was found that sediment deposition occurred on the marsh surface during rising tides at tidal elevations ranging from those barely flooding the creek bank to high spring tides, and that sediment was not remobilized by tidal flows after initial deposition. Sediment deposition occurred on this marsh surface largely because fine sediment in suspension formed flocs. Analysis of inorganic grain size distributions of sediment deposited within 8 m of the tidal creek indicated that 70-80% of this sediment was deposited in a flocculated form. The rest (particles larger than 20 mu m) were deposited as individual particles. In the marsh interior, 25 m from the tidal creek, single grain settling predominated. Reduction of turbulence levels within the vegetation canopy on the marsh also promoted particle settling. The processes controlling sediment deposition did not vary among tides. However, suspended sediment. concentrations near the creek bank increased with increasing tidal amplitude, consequently promoting higher rates of deposition on higher tides. (C) 2000 Academic Press.