Effect of digital elevation model on Mohr-Coulomb geophysical flow model output

Abstract

Digital elevation models (DEMs) used in geospatial analysis like the simulation of geophysical flows, such as floods, landslides, and block and ash flows, differ in resolution, acquisition time and generation methodology, which results in varied representation of topographic features. This study investigates the effects of DEMs on the output of a granular flow model, TITAN2D by comparing the output using different DEMs to that obtained with a “true” representation of the terrain, which is considered to be that obtained by using TOPSAR 5 m data. Seven DEMs at four resolutions from four sources were used for Mammoth Mountain, California, a cumulodome volcano. TITAN2D was run for seven different locations of an eruption of a potential dome and two different collapse volumes. The resulting outputs were subsequently compared with TOPSAR 5 m output, and qualitative and statistical inferences were drawn. DEMs with different resolutions and sources generated different outputs that led to different flow maps. For moderate and smaller scale flows ( $$\mathcal{O}(10^4)$$ m3 – $$\mathcal{O}(10^5) \,\text{m}^3$$ ), different representations can affect the computation of accurate footprint of the flow and fine DEM resolution is critical for correct characterization of these flows.