Hydrological control of large hurricane-induced lahars: evidence from rainfall-runoff modeling, seismic and video monitoring
Por:
Capra L., Coviello V., Borselli L., Márquez-Ramírez V.-H., Arámbula-Mendoza R.
Publicada:
9 mar 2018
Categoría:
Earth and planetary sciences (miscellaneous)
Resumen:
The Volcan de Colima, one of the most active volcanoes in Mexico, is
commonly affected by tropical rains related to hurricanes that form over
the Pacific Ocean. In 2011, 2013 and 2015 hurricanes Jova, Manuel and
Patricia, respectively, triggered tropical storms that deposited up to
400 mm of rain in 36 h, with maximum intensities of 50 mm h(-1) . The
effects were devastating, with the formation of multiple lahars along La
Lumbre and Montegrande ravines, which are the most active channels in
sediment delivery on the south-southwest flank of the volcano. Deep
erosion along the river channels and several marginal landslides were
observed, and the arrival of block-rich flow fronts resulted in damages
to bridges and paved roads in the distal reaches of the ravines. The
temporal sequence of these flow events is reconstructed and analyzed
using monitoring data (including video images, seismic records and
rainfall data) with respect to the rainfall characteristics and the
hydrologic response of the watersheds based on rainfall-runoff numerical
simulation. For the studied events, lahars occurred 5-6 h after the
onset of rainfall, lasted several hours and were characterized by
several pulses with block-rich fronts and a maximum flow discharge of
900 m(3) s(-1). Rainfall-runoff simulations were performer using the
SCS-curve number and the Green-Ampt infiltration models, providing a
similar result in the detection of simulated maximum watershed peaks
discharge. Results show different behavior for the arrival times of the
first lahar pulses that correlate with the simulated catchment's peak
discharge for La Lumbre ravine and with the peaks in rainfall intensity
for Montegrande ravine. This different behavior is related to the area
and shape of the two watersheds. Nevertheless, in all analyzed cases,
the largest lahar pulse always corresponds with the last one and
correlates with the simulated maximum peak discharge of these
catchments. Data presented here show that flow pulses within a lahar are
not randomly distributed in time, and they can be correlated with
rainfall peak intensity and/or watershed discharge, depending on the
watershed area and shape. This outcome has important implications for
hazard assessment during extreme hydro-meteorological events, as it
could help in providing real-time alerts. A theoretical rainfall
distribution curve was designed for Volcan de Colima based on the
rainfall and time distribution of hurricanes Manuel and Patricia. This
can be used to run simulations using weather forecasts prior to the
actual event, in order to estimate the arrival time of main lahar
pulses, usually characterized by block-rich fronts, which are
responsible for most of the damage to infrastructure and loss of goods
and lives.
Filiaciones:
Capra L.:
Centro de Geociencias, Universidad Nacional Autónoma de México (UNAM), Campus Juriquilla, Querétaro, Mexico
Coviello V.:
Centro de Geociencias, Universidad Nacional Autónoma de México (UNAM), Campus Juriquilla, Querétaro, Mexico
Free University of Bozen-Bolzano, Facoltà di Scienze e Tecnologie, Bolzano, Italy
Borselli L.:
Instituto de Geología, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
Márquez-Ramírez V.-H.:
Centro de Geociencias, Universidad Nacional Autónoma de México (UNAM), Campus Juriquilla, Querétaro, Mexico
Arámbula-Mendoza R.:
Centro Universitario de Estudios e Investigaciones en Vulcanología (CUEIV), Universidad de Colima, Colima, Mexico
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