Resolving the turbidity paradox: Tide-weighted remote sensing reveals how morphodynamic siltation overwhelms flow attenuation in a macro-tidal bay
5 affiliations
- 1State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, 310012, China
- 2State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, 310012, China; Key Laboratory of Ocean Space Resource Management Technology, Ministry of Natural Resources, Hangzhou, 310012, China; Corresponding author at: Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China.
- 3Hangzhou Guohai Marine Engineering Survey & Design Institute Co., Ltd., Hangzhou, 310012, China
- 4South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 511458, China
- 5School of Marine Science and Engineering, South China University of Technology, Guangzhou, 511442, China
Abstract
Study region: Sanmen Bay, a macro-tidal embayment, Zhejiang, China. Study focus: This study investigates the physical mechanisms driving decadal turbidity escalation under a regime of widespread hydrodynamic attenuation. Decadal GF-1 satellite observations were processed using a tide-weighted compositing method to eliminate tidal phase biases. A 3D hydrodynamic model (MIKE 3 FM) with decoupled scenarios was applied to isolate the individual and cumulative impacts of natural bathymetric shoaling and engineering structures (reclamations, wind farms, photovoltaic arrays) on regional flow and sediment transport. New hydrological insights for the region: From 2014–2024, the regional mean suspended sediment concentration (SSC) increased from 311.1 to 348.8 mg/L, concurrent with a basin-wide mean flow velocity reduction of 0.05–0.15 m/s. Decoupled numerical experiments reveal that large-scale bathymetric shoaling dictates this regional hydrodynamic attenuation, while coastal engineering structures generate localized flow diversion. The turbidity escalation under diminished tidal forcing is controlled by cohesive bed-property feedbacks. Persistent offshore sediment importation and subsequent deposition continually renew a highly porous surficial mud layer, reducing the critical erosion shear stress ( τ ce ). Consequently, the attenuated tidal currents maintain sufficient energy to trigger frequent sediment resuspension. This deposition process, mechanically amplified by water column volume reductions over accreted shallow flats and flood-dominant tidal asymmetry, establishes a morphodynamic loop that chronically traps sediments within the bay, offering key insights for sediment management in anthropogenically altered coastal hydrological systems.
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BibTeX
@article{wu2026resolving,
title = {{Resolving the turbidity paradox: Tide-weighted remote sensing reveals how morphodynamic siltation overwhelms flow attenuation in a macro-tidal bay}},
author = {Sheng Wu and Wankang Yang and Qingying Yang and Bo Li and Zongyu Li},
journal = {Journal of Hydrology: Regional Studies},
year = {2026},
month = oct,
doi = {10.1016/j.ejrh.2026.104123},
url = {https://doi.org/10.1016/j.ejrh.2026.104123},
note = {CC BY},
}
RIS
TY - JOUR
TI - Resolving the turbidity paradox: Tide-weighted remote sensing reveals how morphodynamic siltation overwhelms flow attenuation in a macro-tidal bay
AU - Sheng Wu
AU - Wankang Yang
AU - Qingying Yang
AU - Bo Li
AU - Zongyu Li
PY - 2026
DA - 2026/10/30
JO - Journal of Hydrology: Regional Studies
DO - 10.1016/j.ejrh.2026.104123
UR - https://doi.org/10.1016/j.ejrh.2026.104123
AB - Study region: Sanmen Bay, a macro-tidal embayment, Zhejiang, China. Study focus: This study investigates the physical mechanisms driving decadal turbidity escalation under a regime of widespread hydrodynamic attenuation. Decadal GF-1 satellite observations were processed using a tide-weighted compositing method to eliminate tidal phase biases. A 3D hydrodynamic model (MIKE 3 FM) with decoupled scenarios was applied to isolate the individual and cumulative impacts of natural bathymetric shoaling and engineering structures (reclamations, wind farms, photovoltaic arrays) on regional flow and sediment transport. New hydrological insights for the region: From 2014–2024, the regional mean suspended sediment concentration (SSC) increased from 311.1 to 348.8 mg/L, concurrent with a basin-wide mean flow velocity reduction of 0.05–0.15 m/s. Decoupled numerical experiments reveal that large-scale bathymetric shoaling dictates this regional hydrodynamic attenuation, while coastal engineering structures generate localized flow diversion. The turbidity escalation under diminished tidal forcing is controlled by cohesive bed-property feedbacks. Persistent offshore sediment importation and subsequent deposition continually renew a highly porous surficial mud layer, reducing the critical erosion shear stress ( τ ce ). Consequently, the attenuated tidal currents maintain sufficient energy to trigger frequent sediment resuspension. This deposition process, mechanically amplified by water column volume reductions over accreted shallow flats and flood-dominant tidal asymmetry, establishes a morphodynamic loop that chronically traps sediments within the bay, offering key insights for sediment management in anthropogenically altered coastal hydrological systems.
SN - 2214-5818
ER -