The role of geological mouth islands on the morphodynamics of back-barrier tidal basins

[摘要] Researchers have extensively investigated theback-barrier islands morphodynamics using numerical methods. However, theinfluence of rocky mouth islands, which may be submerged by sea-level rise,has been rarely explored. Using the Dongshan Bay in southern China as areference, this study numerically explores the long-term morphodynamiceffect of geological constraints (e.g. rocky islands) for back-barrierbasins. Model results indicate that the spatial configuration of mouthislands can considerably affect the morphological development of tidalbasins. The presence of mouth islands narrows the inlet cross-sectional area,increasing flow velocity and residual current, resulting in more sedimentsuspension and transport. Meanwhile, mouth islands tend to increase erosionin the tidal basin and sedimentation in the ebb-delta area. Furthermore, thespatial distribution of mouth islands can also affect tidal basin evolution:the basin-side mouth islands tend to cause more basin erosion with highertidal currents and more sediment transport. In contrast, the delta-side onesmay increase relative sediment deposition in the basin. Finally, largertidal prisms are observed with more mouth islands and with basin-side mouthislands, suggesting that the number and location of islands can affect therelationship between the tidal prism and inlet cross-sectional area. Thismodelling study furthers the understanding of barrier basin morphodynamicsaffected by rocky mouth islands and informs management strategies under achanging environment.

[学科分类] 土壤学