Updating channel morphology in digital elevation models: lahar assessment for Tenenepanco-Huiloac Gorge, Popocatépetl volcano, Mexico

Abstract

In contrast to dramatic flow regime changes by less frequent large-scale volcanic eruptions, those caused by more frequent small-scale processes in volcanic landscapes may also drastically change the direction and dynamics of flow in a drainage system formed solely by fluvial processes. During such periods of channel morphology change, it is necessary to frequently update channel flow parameters to assess preventive measures for civil protection purposes. Often aerial photography is impracticable, since parts of the channels are covered by dense vegetation, while total station and laser topographic surveys are often too slow and costly, particularly during a high frequency of events. This article introduces and validates a new methodology for updating the representation of channel morphology in Digital Elevation Models (DEM) used specifically for assessing the dangers of frequently occurring lahars along gorges in volcanic landscapes during eruptive and non-eruptive periods. The updating of channel cross-sections was achieved by inserting more detailed representative profiles of homogeneous channel sectors in DEMs derived from existing less detailed topographic maps. The channel profiles were surveyed along the thalweg in equidistant points according to Universal Transverse Mercator (UTM) (x,y) coordinates and elevation derived from the existing DEM. The proposed technique was applied at Tenenepanco-Huiloac Gorge on Popocatépetl volcano, Mexico, in an area affected by major lahars during the volcano's most recent eruptive period from 1994 to 2005. The proposed method can reduce the cost and person-hours of a regular channel topographic survey dramatically and the enhanced DEM can determine volume parameters and flood zones associated with the 1 July 1997 and 21 January 2001 lahars, respectively. In addition, the updated DEM with better channel representation allowed a more realistic fluid flow and lahar simulation with the process-based TITAN2D model.

Factors controlling erosion/deposition phenomena related to lahars at Volcán de Colima, Mexico

“…This latter slope value represents a higher value than that observed in Ruapehu of ∼ 2.7-0.7 • (Fagents and Baloga, 2006) or the < 1.2 • found by Pierson (1995) for snow-clad volcanoes, but a similar value to those observed in Popocatépetl volcano (i.e., < 6.5 • , Capra et al, 2004;Muñoz-Salinas et al, 2008). On the other hand, the dominant erosional behavior of lahars above 8 • is also consistent with observations made in other volcanic environments (e.g., Procter et al, 2010) and in Alpine basins affected by debris flows (e.g., Berger et al, 2011;Schürch et al, 2011;Theule et al, 2015).…”

“…Furthermore, additional volume changes can oc-R. Vázquez et al: Factors controlling erosion/deposition phenomena cur by dilution due to tributary streamflows, overrunning active stream channels or entrainment of water-saturated sediments (Pierson and Scott, 1985;Cronin et al, 1999). All of these flow changes control the capacity of lahars to modify the morphology of the channels where they flow, as observed in several studies (Muñoz-Salinas et al, 2008Doyle et al, 2009Doyle et al, , 2011Starheim et al, 2013;Andrés de Pablo et al, 2014), not only in volcanic environments, but also in mountainous regions in the form of debris flows. The role that the slope, the sediment availability, rainfall distribution and flow dynamics play, among other parameters, has been studied for a long time (e.g., Coe et al, 2008;Guthrie et al, 2010;Berger et al, 2011;Schürch et al, 2011;Abancó and Hürlimann, 2014;Theule et al, 2015), and has served to extrapolate these findings to volcanic conditions.…”

Runout and deposit morphology of Bingham fluid as a function of initial volume: implication for debris flow modelling

“…So, the results of those estimates are directly used in empirical models such as Laharz to reproduce the flow trajectory and maximum runout (Dávila et al 2007;Macias et al 2008;Schneider et al 2008;Muñoz-Salinas et al 2008;among others). If the empirical models give no information about velocity and poor information about flow depth, more sophisticated numerical models like Titan 2D , SPH (Pastor et al 2009b), or Dan 2D (Hungr 1995), among others, are used for this purpose.…”

“…(Janda et al 1985;Gartner et al 2008;Marchi et al 2010). Besides the volume value, how the initial mass is placed on the underlying topography is also important, but sometimes, the geometry is unknown or too complicated, so simple setups (cylinder, ellipsoidal, …) or topographical interpolations are used to simulate landslides Yoshida and Sugai 2007;Muñoz-Salinas et al 2008).…”

A GIS-based method to determine the volume of lahars: Popocatépetl volcano, Mexico

“…The path length of one gorge was divided into homogeneous sections (i.e. long-sections of the channel with similar width, depth and shape; Muñoz-Salinas et al, 2008). During field work, one profile was surveyed along the perimeter of the lahar sediment located on a representative crosssection of each homogeneous section.…”