Comparisons of Numerical Models on Formation of Sediment Deposition Induced by Tsunami Run-Up

Abstract

Tsunami sediments provide direct evidence of tsunami arrival histories for tsunami risk assessments. Therefore, it is important to understand the formation process of tsunami sediment for tsunami risk assessment. Numerical simulations can be used to better understand the formation process. However, as the formation of tsunami sediments is affected by various conditions, such as the tsunami hydraulic conditions, topographic conditions, and sediment conditions, many problems remain in such simulations when attempting to accurately reproduce the tsunami sediment formation process. To solve these problems, various numerical models and methods have been proposed, but there have been few comparative studies among such models. In this study, inter-model comparisons of tsunami sediment transport models were performed to improve the reproducibility of tsunami sediment features in models. To verify the reproducibility of the simulations, the simulation results were compared with the results of sediment transport hydraulic experiments using a tsunami run-up to land. Two types of experiments were conducted: a sloping plane with and without coverage by silica sand (fixed and movable beds, respectively). The simulation results confirm that there are conditions and parameters affecting not only the amount of sediment transport, but also the distribution. In particular, the treatment of the sediment coverage ratio in a calculation grid, roughness coefficient, and bedload transport rate formula on the fixed bed within the sediment transport model are considered important.

Resolving tsunami wave dynamics: Integrating sedimentology and numerical modelling

“…Finally, the discretised equations are solved using a Newton non‐linear solver algorithm using the PETSc library (Balay et al, 2017). Note the model does not include algorithms to simulate the bedload transport of sediment as this is challenging and requires calibration even when comparing to laboratory data (Yamamoto et al, 2021).…”

“…Regardless of the type of approach taken, a key part of any interpretation is a thorough understanding of the depositional mechanisms that occur during tsunami inundation. To date, this is poorly known (Costa & Andrade, 2020), which remains a challenge when interpreting palaeotsunami deposits (Yamamoto et al, 2021).…”