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Multiscale Superposition and Decomposition of Field‐Measured Suspended Sediment Concentrations: Implications for Extending 1DV Models to Coastal Oceans With Advected Fine Sediments
Author(s) -
Zhang Shaotong,
Nielsen Peter,
Perrochet Pierre,
Jia Yonggang
Publication year - 2021
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2020jc016474
Subject(s) - advection , settling , sediment , superposition principle , sediment transport , geology , filter (signal processing) , decomposition , geomorphology , soil science , environmental science , chemistry , physics , computer science , organic chemistry , quantum mechanics , environmental engineering , computer vision , thermodynamics
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.