High-resolution modeling of tsunami run-up flooding: a case study of flooding in Kamaishi city, Japan, induced by the 2011 Tohoku tsunami

Abstract

Abstract. Run-up processes of the 2011 Tohoku tsunami into the city of Kamaishi, Japan, were simulated numerically using 2-D shallow water equations with a new treatment of building footprints. The model imposes an internal hydraulic condition of permeable and impermeable walls at the building footprint outline on unstructured triangular meshes. Digital data of the building footprint approximated by polygons were overlaid on a 1.0 m resolution terrain model. The hydraulic boundary conditions were ascertained using conventional tsunami propagation calculation from the seismic center to nearshore areas. Run-up flow calculations were conducted under the same hydraulic conditions for several cases having different building permeabilities. Comparison of computation results with field data suggests that the case with a small amount of wall permeability gives better agreement than the case with impermeable condition. Spatial mapping of an indicator for run-up flow intensity (IF = (hU2)max, where h and U respectively denote the inundation depth and flow velocity during the flood, shows fairly good correlation with the distribution of houses destroyed by flooding. As a possible mitigation measure, the influence of the buildings on the flow was assessed using a numerical experiment for solid buildings arrayed alternately in two lines along the coast. Results show that the buildings can prevent seawater from flowing straight to the city center while maintaining access to the sea.

Effect of Land Cover on Tsunami Overland Flow Propagation: A Case Study of Painan, West Sumatra, Indonesia

“…However, the flow velocity increases between buildings or roads. These are also consistent with previous studies [25,28]. They stated that tsunami propagation in rivers and roads has a greater height due to narrowing and mild slope.…”

“…Paths and flow patterns change due to buildings and road alignment. The influence of roughness on water flows was discussed in previous studies [23]- [25]. Other studies stated that buildings in urban areas could act as barriers or protectors.…”

Evaluation of the Effect of Hamao Detention Pond on Excess Runoff from the Abukuma River in 2019 and Simple Remodeling of the Pond to Increase Its Flood Control Function

“…For specific and detailed facility planning, numerical simulation using a more precise model will be required. For example, a numerical model using an unstructured triangular grid system [20] can express the effects of the existence of structures, such as houses and roads, in floodplains and the effects of trees in river channels on the flow field, but the calculation load is very high. Therefore, preliminary studies to readily compare alternatives possible under the given topographic and land use conditions are required.…”

The Tsunami Threat to Sydney Harbour, Australia: Modelling potential and historic events

“…Spatially variable friction 50 and the permeability of buildings 51 are known to affect tsunami impact prediction including runup and inundation extent patterns. Experimentation by Cardno 29 provides some confidence in the friction applied to this model domain, however, there is likely to be some overestimation of inundation extent for areas with buildings for the broad scale model.…”