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 ASTER and SRTM elevation datasets cause the modeled inundation extent to be much less compared with the other datasets and observations. Therefore, ASTER and SRTM should not be used to underpin tsunami inundation models. A model mesh resolution of 25 m 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 DTM for modeling tsunami inundation extent with further work needed to resolve the scale at which surface roughness should be parameterized.

Uncertainties in Tidally Adjusted Estimates of Sea Level Rise Flooding (Bathtub Model) for the Greater London

“…In this regard, Gallegos et al [67] suggested that a horizontal resolution of 5 m may be required for detailed evaluation of risk assessment, so SRTM DEM may not have sufficient resolution to simulate flood inundation with confidence. Similar observations have been made in other studies [3,7,63]. However, the 50 m DEM, which is an OS derivative from 10 m contours using photogrammetric techniques that are updated annually using other high-resolution terrain datasets, provides much better estimates of the total flooded areas despite the low horizontal resolution [34].…”

“…This indicates that the DTM contains significantly lower elevation values, which results in a greater flooded area than a DSM. Griffin et al [63] argued that the best approach for modelling flood inundation is to use a DTM together with an appropriate surface roughness condition, but their studies deal with tsunami inundation where the water flow has the force to destroy buildings. For SLR flooding, the ideal DEM may lie between a DSM and a DTM, because some structures may resist flow, while others allow water to flow through them and may even collapse with prolonged flooding.…”

Effects of Scale and Input Data on Assessing the Future Impacts of Coastal Flooding: An Application of DIVA for the Emilia-Romagna Coast

“…In open terrain, the SRTM elevation will represent the ground elevation, but in vegetated or urban areas the ground-elevation might be overestimated. According to Gesch (2009), this mix of ground elevation and non-bare ground elevation in SRTM data could be a source of error in inundation mapping in vegetated and urban areas (Baugh et al, 2013;Lewis et al, 2013;Griffin et al, 2015). The second data set used is the (2) Light detection and ranging (LiDAR) digital elevation model (datum wgs84) with a spatial resolution of 5 m and a vertical accuracy of (±)20 cm which was provided by the Emilia-Romagna region.…”

Tsunami evacuation plans for future megathrust earthquakes in Padang, Indonesia, considering stochastic earthquake scenarios

“…For instance, the deterministic approach is more communicable to the authorities for developing post-disaster recovery and mitigation plans (McGuire, 2001). However, implementation of deterministic scenarios may oversimplify the tsunami hazards and risks, leading to imprecise mitigation plans (Griffin et al, 2015;Mueller et al, 2015). In contrast, the probabilistic approach requires the proper consideration of regional earthquake characteristics, including uncertainties in the earthquake rupture size, its focal mechanism, and the depth and spatial heterogeneity of the earthquake slip.…”

“…Recently, Muhammad et al (2016) have evaluated the tsunami potential in Padang by developing the stochastic tsunami simulation method, allowing us to generate numerous scenarios of stochastic tsunami hazard. However, that work was limited to evaluating the tsunami hazards offshore and near the coast only because of the gross bias of the elevation model in Padang (Griffin et al, 2015) and, therefore, was not suitable to carry out rigorous assessment of tsunami mitigation systems. The gross bias of the elevation model in Padang is due to the use of global digital elevation model (DEM; i.e., GDEM2) as the elevation data for the stochastic tsunami simulation.…”