Evaluation of ASTER and SRTM DEM data for lahar modeling: A case study on lahars from Popocatépetl Volcano, Mexico

Abstract

Lahars are among the most serious and far-reaching volcanic hazards. In regions with potential interactions of lahars with populated areas and human structures the assessment of the related hazards is crucial for undertaking appropriate mitigating actions and reduce the associated risks. Modeling of lahars has become an important tool in such assessments, in particular where the geologic record of past events is insufficient. Mass-flow modeling strongly relies on digital terrain data. Availability of digital elevation models (DEMs), however, is often limited and thus an obstacle to lahar modeling. Remote-sensing technology has now opened new perspectives in generating DEMs. In this study, we evaluate the feasibility of DEMs derived from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and the Shuttle Radar Topography Mission (SRTM) for lahar modeling on Popocatépetl Volcano, Mexico. Two GIS-based models are used for lahar modeling, LAHARZ and a flow-routing-based debris-flow model (modified single-flow direction model, MSF), both predicting areas potentially affected by lahars. Results of the lahar modeling show that both the ASTER and SRTM DEMs are basically suitable for use with LAHARZ and MSF. Flow-path prediction is found to be more reliable with SRTM data, though with a coarser spatial resolution. Errors of the ASTER DEM affecting the prediction of flow paths due to the sensor geometry are associated with deeply incised gorges with north-facing slopes. LAHARZ is more sensitive to errors of the ASTER DEM than the MSF model. Lahar modeling with the ASTER DEM results in a more finely spaced predicted inundation area but does not add any significant information in comparison with the SRTM DEM. Lahars at Popocatépetl are modeled with volumes of 1 × 10 5 to 8 × 10 6 m 3 based on ice-melt scenarios of the glaciers on top of the volcano and data on recent and historical lahar events. As regards recently observed lahars, the travel distance of lahars of corresponding volume modeled with LAHARZ falls short by 2 to 4 km. An important finding is that the travel distance of potential lahar events modeled with LAHARZ may differ by about 2 km when using SRTM or ASTER data because of varying lateral flow-volume distribution. As a consequence, verification and sensitivity analysis of the DEM is fundamental to deriving hazard maps from predicted modeled inundation areas. Because of the global coverage of this type of remote-sensing data, the conclusion that both SRTM and ASTER-derived DEMs are feasible for lahar modeling opens a wide field of application in volcanic-hazards studies.

Assessing lahars from ice-capped volcanoes using ASTER satellite data, the SRTM DTM and two different flow models: case study on Iztaccíhuatl (Central Mexico)

“…A lahar modelled on the SRTM3 DTM at the northeastern slope and with a volume of 1×10 6 m 3 affects the central part of San Agustín Atzompa while the same volume on the ASTER DTM stops 2.5 km upstream and represents no hazard for the settlement ( Fig. 9 and 10; this effect was also observed by Huggel et al, 2008). Stevens et al (2002) found similar effects concerning the flow length on different DTMs but not to that extent.…”

“…H/L ratios for the lahar modelling between 0.2 and 0.15 were used, corresponding to published case studies (Siebe et al, 1996;Vallance et al, 2001;Capra et al, 2004). The volumes of debris flows correlate with the H/L ra- tio as demonstrated for lahars at Popocatépetl volcano by Huggel et al (2008). That means that the greater the volume of a debris flow, the smaller is the corresponding H/L ratio (Legros, 2002).…”

“…That means that the greater the volume of a debris flow, the smaller is the corresponding H/L ratio (Legros, 2002). After the relation given by Huggel et al (2008), the chosen values approximately represent volumes between 1×10 5 m 3 and 1×10 7 m 3 .…”

“…4.4 Influence of the DTM on lahar models Huggel et al (2008) have shown that the quality and resolution of the DTM can have an important effect on the flow paths and runout distances of simulated lahars. For the MSF model, the changes of the runout distance between the runs on the SRTM-DTM and the ASTER-DTM are minor.…”

“…The lahars simulated in this study represent debris flow types with sediment concentrations similar to the observed ice-melt-triggered lahars on Popocatépetl in City, the study area and Puebla is derived from SRTM3 elevation model. The dotted area shown as 'prehispanic lahars' represent the approximate extent of areas flooded by repeated lahar events from Popocatépetl, Iztaccíhuatl and La Malinche after Siebe et al (1996). al., 1998; Julio Miranda and Delgado Granados, 2003;Sheridan et al, 2005;Walder et al, 2005;Hubbard et al, 2006;Davila et al, 2007;Huggel et al, 2008). By applying such tools to Iztaccíhuatl volcano in Mexico, we show how an initial hazard evaluation can be carried out relatively fast and at low cost.…”