An evaluation of onshore digital elevation models for modeling tsunami inundation zones

Abstract

A sensitivity study is undertaken to assess the utility of different onshore digital elevation models (DEMs) for simulating the extent of tsunami inundation using case studies from two locations in Indonesia. We compare airborne IFSAR, ASTER, and SRTM against high resolution LiDAR and stereo-camera data in locations with different coastal morphologies. Tsunami inundation extents modeled with airborne IFSAR DEMs are comparable with those modeled with the higher resolution datasets and are also consistent with historical run-up data, where available. Large vertical errors and poor resolution of the coastline in the ASTERand SRTMelevation datasets cause the modeled inundation extent to be much less compared with the other datasets and observations. Therefore, ASTERandSRTMshould not be usedto underpin tsunami inundation models. A model mesh resolution of 25m was sufficient for estimating the inundated area when using elevation data with high vertical accuracy in the case studies presented here. Differences in modeled inundation between digital terrain models (DTM) and digital surface models (DSM) for LiDAR and IFSAR are greater than differences between the two data types. Models using DTM may overestimate inundation while those using DSM may underestimate inundation when a constant Manning’s roughness value is used. We recommend using DTMfor modeling tsunami inundation extent with further work needed to resolve the scale at which surface roughness should be parameterized.