Suspended particulate matter concentration in response to tidal hydrodynamics in a long mesotidal floodway

Xiao Cong

Kawanisi Kiyosi

Al Sawaf Mohamad Basel

Estuarine, Coastal and Shelf Science

Analyses of seasonal data obtained using acoustic Doppler current profilers provide an understanding of the behavior of suspended particulate matter concentration (SPMC) toward different forcings in tide-controlled floodways. In this work, the relative contributions of external forcings on SPMC variability were quantified in a tidal river system using singular spectrum analysis (SSA). The main environmental features affecting SPMC were identified as i) spring-neap tidal oscillation, ii) the ebb/flood velocities, and iii) tidal straining. Large SPMC fluctuations occurred under strong mixing states and were directly related to the sediment resuspension stirred up by spring-neap tidal cycles (73.6%–81.9%) and ebb/flood velocities (9.6%–19.5%). On the seasonal scale, river discharge is the key variable explaining the downstream flushing and promoting the occurrence of a convergence zone at the floodway. Upstream from the floodway (greater than 4.8 km from the river mouth), the spring-neap tidal oscillation dominated the suspended particulate matter (SPM) mobility under low river discharge. Two interesting findings were revealed in this work: (i) the SPMC/SPM transport variation responses to tidal forcing (tidal asymmetry) were dominated and modified by river discharge and (ii) the effect of river discharge on the SPMC/SPM transport did not result in a uniform state along the floodway. It is believed that these findings provide further understanding of the dynamics of suspended sediments in shallow tidal systems.

Acoustic Doppler current profiling

Tidal hydrodynamics

Suspended particulate matter

Estuary

Single spectrum analysis

Spring-neap tidal oscillation

eng

Elsevier

© 2020. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

This is not the published version. Please cite only the published version. この論文は出版社版ではありません。引用の際には出版社版をご確認、ご利用ください。

[ISSN] 0272-7714

[DOI] 10.1016/j.ecss.2019.106525

[DOI] https://doi.org/10.1016/j.ecss.2019.106525