<p>The eastern English Channel is a highly energetic macrotidal region where sediment transport is driven by the interaction between tidal currents and wind forcing. A high-resolution three-dimensional hydrodynamic–sediment modelling system was calibrated and evaluated against multiple observational datasets, including satellite-derived suspended particulate matter, hydrodynamic fields, and seabed sediment maps. The model reproduced the main spatial patterns of sediment distribution and yielded realistic suspended sediment concentrations in both the surface and near-bed layers. The calibrated configuration was then used to analyse sediment transport during two contrasting winter periods: typical winter conditions (December 2021) and an extreme wind–tide co-occurrence event associated with Storm Eunice (February 2022). The results highlighted the key role of Cape Gris-Nez (CGN) in shaping local hydrodynamics in the Dover Strait, where strong tidal currents and flow constriction generated complex circulation patterns. A clockwise recirculation gyre developed in Wissant Bay during flood tide under both conditions, promoting sediment retention. Under typical conditions, surface concentrations remained below 0.1 g L<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(^{-1}\)</EquationSource> </InlineEquation>, and the suspended sediment was dominated by fine particles. During the extreme event, flood currents intensified markedly, whereas ebb currents remained comparatively weak, thereby increasing tidal asymmetry. The intensified flood currents increased sediment mobilisation, with near-bed concentrations locally exceeding 1 g L<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(^{-1}\)</EquationSource> </InlineEquation> and marked enrichment in the sand fraction throughout the water column; the sand fraction accounted for up to 70% of suspended sediment at the surface. Sediment budget analysis revealed contrasting morphodynamic regimes: the area south of CGN acted as a persistent high-energy transit zone, resulting in net sediment export. By contrast, Wissant Bay, north of CGN, acted as an accumulation zone, where weaker currents within the recirculation cell promoted sediment retention. Extreme conditions strongly amplified sediment fluxes and locally altered sediment budgets, enhancing net export south of CGN and net import and deposition in Wissant Bay. Overall, the spatial organisation of transport was largely governed by persistent circulation patterns, while the extreme event examined here exerted a disproportionate influence on sediment redistribution.</p>

Hydro-sedimentary dynamics in a narrow macrotidal strait: the eastern English Channel

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发表日期：

2026年8月3日

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Elena Alekseenko,
Alexei Sentchev

摘要

The eastern English Channel is a highly energetic macrotidal region where sediment transport is driven by the interaction between tidal currents and wind forcing. A high-resolution three-dimensional hydrodynamic–sediment modelling system was calibrated and evaluated against multiple observational datasets, including satellite-derived suspended particulate matter, hydrodynamic fields, and seabed sediment maps. The model reproduced the main spatial patterns of sediment distribution and yielded realistic suspended sediment concentrations in both the surface and near-bed layers. The calibrated configuration was then used to analyse sediment transport during two contrasting winter periods: typical winter conditions (December 2021) and an extreme wind–tide co-occurrence event associated with Storm Eunice (February 2022). The results highlighted the key role of Cape Gris-Nez (CGN) in shaping local hydrodynamics in the Dover Strait, where strong tidal currents and flow constriction generated complex circulation patterns. A clockwise recirculation gyre developed in Wissant Bay during flood tide under both conditions, promoting sediment retention. Under typical conditions, surface concentrations remained below 0.1 g L \(^{-1}\) , and the suspended sediment was dominated by fine particles. During the extreme event, flood currents intensified markedly, whereas ebb currents remained comparatively weak, thereby increasing tidal asymmetry. The intensified flood currents increased sediment mobilisation, with near-bed concentrations locally exceeding 1 g L \(^{-1}\) and marked enrichment in the sand fraction throughout the water column; the sand fraction accounted for up to 70% of suspended sediment at the surface. Sediment budget analysis revealed contrasting morphodynamic regimes: the area south of CGN acted as a persistent high-energy transit zone, resulting in net sediment export. By contrast, Wissant Bay, north of CGN, acted as an accumulation zone, where weaker currents within the recirculation cell promoted sediment retention. Extreme conditions strongly amplified sediment fluxes and locally altered sediment budgets, enhancing net export south of CGN and net import and deposition in Wissant Bay. Overall, the spatial organisation of transport was largely governed by persistent circulation patterns, while the extreme event examined here exerted a disproportionate influence on sediment redistribution.