Mechanism of Phase Lag Between Current Speed and Suspended Sediment: Combined Effect of Erosion, Deposition, and Advection

Zhu, Zichen; Wang, Yongzhi; Hu, Zejian; Bian, Shuhua; Zhang, Yongqiang; Xiong, Congbo

doi:10.1007/s11802-019-3553-y

Cited by 3 publications

(1 citation statement)

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“…Consequently, when C adv ( t ) is nonnegligible, the inclusion of the C adv ( t ) component in the total C ( t ) will invalidate the direct application of 1DV models. In this case, more complex 2D (e.g., Bass et al., 2002) or 3D numerical models (e.g., Mulligan et al., 2019; Wang et al., 2007; Zhu et al., 2019) are needed; however, such models conversely rely on the calibration of parameters from the best fits between available observations and simple 1DV models. Winterwerp (2011) proposed a reasonable approach in which all horizontal gradients ( C adv ( t )) were stripped from the 3D modeling for three‐dimensional simulations of the hydrodynamics and transport of matter in shallow water; however, the modeling of horizontal gradients may introduce errors in subsequent analyses.…”

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confidence: 99%

Multiscale Superposition and Decomposition of Field‐Measured Suspended Sediment Concentrations: Implications for Extending 1DV Models to Coastal Oceans With Advected Fine Sediments

et al. 2021

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One-dimensional vertical (1DV) sediment diffusion-settling models are practical tools for analyzing sediment transport paths (Pearson et al., 2019; Winterwerp et al., 2011; Yu et al., 2012) and optimizing parameters via reaching best fits with the available observations of suspended sediment concentrations profiles C(t) (e.g., Hill et al., 2003). Such parameters include the eddy diffusivity (D s) and settling velocity (w s) of the suspended sediments, and erosion rate (E r) of the bottom sediments, which are all key parameters for performing theoretical calculations or numerical simulations of coastal processes over a larger domain. However, 1DV models are only valid when the sediments are dominated by local vertical processes. For sandy sediments, an assumption of local resuspension (LR) such that C(t) correlates with the bed shear stress τ(t)∼    2 V t (where V is horizontal velocity) is usually valid and the 1DV models are adequate Abstract One-dimensional vertical (1DV) diffusion-settling models are practical tools for sediment transport analysis of sands, which is mostly a local process. However, for fine sediments, the observed concentrations C(t) can be mixed via horizontal advection (HA) due to the lower settling velocity, which makes the C(t) not necessarily a local process, thus making 1DV models invalid. It is important to determine the qualitative significance of HA or quantitatively separate HA signals when applying 1DV models to environments with advected fine sediments. Here, novel methods are combined to (1) qualitatively identify the physical mechanisms underlying C(t) variations and determine whether HA is significant via multiscale frequency superposition and (2) quantitatively decompose C(t) components according to their physical mechanisms via spectral filter decomposition. In situ observational data of C(t) and concurrent hydrodynamics in the subaqueous Yellow River Delta is employed to analyze the methods' performance. The decomposed signals are reasonable because they can be interpreted in light of other observed physical processes. The results indicated that M2 tidal advection contributed 8.30% by carrying sediments from 1.6 km upstream of the flood tides, M4 and M6 + M8 tidal resuspension contributed 4.16% and 3.96%, respectively, by periodically resuspending a "fluffy layer." Waves resuspended sediments from an erosion center 5 km upstream of the flood tides and contributed to 76.49% of the elevated C(t). The proposed methods can exclude HA signals from the measured C(t) to increase the applicability of 1DV models to environments with advected fines when C(t) and hydrodynamics are measured. Plain Language Summary For fine-grained sediments, measured suspended sediment concentrations can be either resuspended locally or advected by tidal currents from a faraway location. The present paper found that the qualitative intensities of these components can be judged from the temporal pattern of suspended sediment concentrations using frequency superposition analysis. Furthermore, the qu...

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