Abstract
Conventional tsunami computations on coarser grids have employed Manning’s friction coefficients of subgrid equivalent roughness for buildings, vegetation and public facilities (roads, dikes and so on), depending on land-use at the grid location. This equivalent roughness macroscopically models to integrate all effects of resistances against the flow within the computational cells; that is, drag force and pressure reduction behind structures in addition to wall roughness defined in turbulent boundary layer theory. Recently high-resolution land elevation data (2-m resolution), measured by an aerial laser profiler, has been used for computing local inundation of tsunami flood. Since the high-resolution data resolves major buildings and facilities, the mechanical contributions of the structures, such as drag and pressure reduction, are included in the computed result. In this case, conventional equivalent friction may be unacceptable to use.
Highlights
Conventional tsunami computations on coarser grids have employed Manning’s friction coefficients of subgrid equivalent roughness for buildings, vegetation and public facilities, depending on land-use at the grid location
This study proposes the novel semi-Lagrangian computational model for computing comprehensive tsunami run-up process, fully coupled with bedload sediment transport computation, on high resolution elevation data under Adaptive-Mesh-Refinement (AMR) environment
In the AMR environment, the run-up wave front was precisely resolved and tracked at highest resolution (1.2-m), to maintain a sharp wave profile of tsunami propagating on the river and overflowing from the dikes (See Fig. 1).The current model was applied to the flood case of Kitakami River
Summary
Conventional tsunami computations on coarser grids have employed Manning’s friction coefficients of subgrid equivalent roughness for buildings, vegetation and public facilities (roads, dikes and so on), depending on land-use at the grid location. The 2011 Tohoku tsunami propagated along Kitakami River, Miyagi prefecture, Japan, and collapsed river dikes, causing significant flood over wide area and human damages including 84 deaths of school children. In order to understand the temporal extension of the tsunami inundation in the river basin, local overflow from the river dikes and the land erosion by the run-up tsunami need to be precisely estimated.
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