Study on topographic model using LIDAR for tsunami simulation

This study discusses the creation method of topographic models from LIDAR data with the view of using them for tsunami simulation. Additionally, an examination regarding the improvement of simulation accuracy and topographic approximation of topographic models is carried out for the coastal region of Taro area of Miyako City in Iwate Prefecture in Japan using LIDAR data, comparing the simulation results of numerical analysis with different grid spacing from 5m to 40m. As for the differences due to changes in grid size, we can see that the modeling accuracy of sea walls and minute topography with a height of 1-2m is greatly affected by grid size. The tendency that the simulated inundation areas become smaller as grid sizes become smaller was observed in the urban areas behind embankments. The simulated inundation depths of the urban areas also became smaller in accordance with the decrease of grid size. This indicates that the detailed topographic model with smaller grids can interrupt the tsunami flow, because the smaller grids can express the minute ruggedness of the actual topography. Thus, it is important to use the smaller grid with precise height data in tsunami simulation in order to evaluate the hazard area adequately.