Comprehensive Field Study of Swash-Zone Processes. II: Sheet Flow Sediment Concentrations during Quasi-Steady Backwash
Comprehensive Field Study of Swash-Zone Processes. II: Sheet Flow Sediment Concentrations during Quasi-Steady Backwash
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DOI：
10.1061/(asce)ww.1943-5460.0000209
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发表时间：
2014-01-01
影响因子：
2.2
通讯作者：
Russell, Paul
中科院分区：
文献类型：
--
作者：
Lanckriet, Thijs;Puleo, Jack A.;Russell, Paul
在自然条件下首次测量了薄层水流泥沙浓度剖面，作为对沼泽区水动力学和泥沙输运进行全面实地研究的一部分。三个电导率浓度剖面仪（CCP）测量的泥沙浓度剖面在片流层与1毫米的分辨率在一个耗散海滩的冲带。本文主要研究亚重力运动产生的准定常扰动事件中的面流，此时相位滞后、表面产生的湍流和加速度的影响都很小。薄层水流含沙量剖面在剖面的下段呈线性，在剖面的上段呈幂律，在含沙量为0.20-0.30时出现过渡。浓度分布的形状是自相似的测量片流层厚度范围从6到18毫米。由于自相似性，一个单一的浓度分布曲线可以用来描述归一化的配置文件的整个范围内的片材厚度，导致改进的估计片流层厚度在一个简单的分析模型。片流层厚度和片负荷，在片流层中动员的沉积物质量，是很好的相关性与水动力强迫的流动性数（R2=0.60片厚度和R2=0.53片负荷）。(C)2014年美国土木工程师学会。
Sheet flow sediment concentration profiles were measured in natural conditions for the first time as part of a comprehensive field study on swash-zone hydrodynamics and sediment transport. Three conductivity concentration profilers (CCPs) measured the sediment concentration profile in the sheet flow layer with a 1-mm resolution in the swash zone of a dissipative beach. This paper focuses on sheet flow during quasi-steady backwash events generated by infragravity motion when the effects of phase lags, surface-generated turbulence, and accelerations are small. The sheet flow sediment concentration profile has a linear shape in the lower section of the profile and a power-law shape in the upper section, with the transition occurring at sediment volume fractions of 0.20-0.30. The shape of the concentration profile is self-similar for measured sheet flow layer thicknesses ranging from 6 to 18 mm. Because of the self-similarity, a single concentration profile curve can be used to describe the normalized profile for the entire range of sheet thicknesses, leading to improved estimates of the sheet flow layer thickness in a simple analytical model. The sheet flow layer thickness and sheet load, the sediment mass mobilized in the sheet flow layer, are well correlated with the hydrodynamic forcing represented by the mobility number (r2=0.60 for sheet thickness and r2=0.53 for sheet load). (C) 2014 American Society of Civil Engineers.