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<p>Sediment siltation in the Deepwater Navigational Channel (DNC) of the Changjiang River Estuary (CRE) remains a persistent critical challenge. A numerical model was developed to investigate the near-bottom transport of sedimentladen gravity currents in the CRE and their potential contribution to siltation. The model successfully reproduces the gravity current process of near-bottom high-concentration sediment through the integration of the three-dimensional Herschel-Bulkley rheological model, incorporating combined stratification of salinity and sediment. The model was validated through simulations of idealized estuarine sediment stratification and flume slope flow experiments with fluid mud, followed by application to the CRE with verification against field-observed data. The simulation results demonstrate that stratification promotes the formation of high sediment concentrations near the bottom. During tidal transitions, the reduction in longitudinal tidal forcing along the North Passage (NP) enhances sediment retention, resulting in accumulated high sediment concentrations along the DNC sides in the middle–lower sections. Gravity currents predominantly occur during the flood-to-ebb tide transition and significantly influence lateral bottom sediment transport beyond typical tidal dynamics. Quantitative assessment indicates that lateral gravity currents may contribute up to 68% of DNC siltation, suggesting that near-bottom high sediment concentration gravity currents substantially impact siltation in the mid-lower section of the DNC.</p>

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Modeling Investigation of the Mechanism of Deepwater Navigational Channel Siltation in the Changjiang River Estuary

  • 期刊论文

  • 发表日期：

    2026年4月1日

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  • Gao-chuang Shi,
  • Jin-feng Zhang,
  • Zhang-yi Zhao,
  • Qing-he Zhang,
  • Bing Yan,
  • Hua Yang

摘要

Sediment siltation in the Deepwater Navigational Channel (DNC) of the Changjiang River Estuary (CRE) remains a persistent critical challenge. A numerical model was developed to investigate the near-bottom transport of sedimentladen gravity currents in the CRE and their potential contribution to siltation. The model successfully reproduces the gravity current process of near-bottom high-concentration sediment through the integration of the three-dimensional Herschel-Bulkley rheological model, incorporating combined stratification of salinity and sediment. The model was validated through simulations of idealized estuarine sediment stratification and flume slope flow experiments with fluid mud, followed by application to the CRE with verification against field-observed data. The simulation results demonstrate that stratification promotes the formation of high sediment concentrations near the bottom. During tidal transitions, the reduction in longitudinal tidal forcing along the North Passage (NP) enhances sediment retention, resulting in accumulated high sediment concentrations along the DNC sides in the middle–lower sections. Gravity currents predominantly occur during the flood-to-ebb tide transition and significantly influence lateral bottom sediment transport beyond typical tidal dynamics. Quantitative assessment indicates that lateral gravity currents may contribute up to 68% of DNC siltation, suggesting that near-bottom high sediment concentration gravity currents substantially impact siltation in the mid-lower section of the DNC.