5:15 PM - 7:15 PM
[AOS21-P06] Internal Tide Breaking Over Bumpy Shaped Topography
Keywords:Internal tide, Numerical simulations, Bumpy shaped topography
Internal wave breaking in coastal regions generates strong currents and vertical mixing, playing a crucial role in nutrient distributions. Understanding the relationship between internal waves and seabed topography is essential for evaluate coastal dynamics and ecosystems. However, internal wave breaking over shallow topography has not been investigated well. This study presents internal wave breaking bumpy-shaped seabed topography using a two-dimensional nonhydrostatic hydrodynamic model SUNTANS with a sediment resuspension model. To evaluate internal wave energy budgets, internal wave energy flux (E) was calculated. As the topographic slope steepen, the proportion of reflected waves (ER) increases, while the proportion of transmitted waves (ET) and energy dissipation decrease. When the crest of the bump locates at the thermocline depth, sediment resuspension occur on the downstream side. In contrast, when the crest locates at deeper than the thermocline, sediment resuspension is observed on the upstream side. Several model results are compared for evaluate effects of changes in bumpy-shaped topography, a smooth normal distribution-shaped topography (control case) and stepped-like topographies with the same height and volume. Model results show that differences in the step scale cause up to 40% variations in energy reflection and up to 55% variations in energy dissipation. Additionally, sediment resuspension is suppressed as the step scale increases. The bottom shear stress and vertical eddy diffusivity are locally enhanced at step edges and the crest of the bumpy topography. However, the area-averaged values of these parameters are higher in the smooth normal distribution-shaped topography. The findings of this study provide valuable insights into assessing the environmental impacts of seabed structures associated with their shape.