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Titel |
A GRASS GIS Semi-Stochastic Model for Evaluating the Probability of Landslides Impacting Road Networks in Collazzone, Central Italy |
VerfasserIn |
Faith E. Taylor, Michele Santangelo, Ivan Marchesini, Bruce D. Malamud |
Konferenz |
EGU General Assembly 2013
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 15 (2013) |
Datensatznummer |
250078787
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Zusammenfassung |
During a landslide triggering event, the tens to thousands of landslides resulting from the
trigger (e.g., earthquake, heavy rainfall) may block a number of sections of the road network,
posing a risk to rescue efforts, logistics and accessibility to a region. Here, we present initial
results from a semi-stochastic model we are developing to evaluate the probability of
landslides intersecting a road network and the network-accessibility implications of this
across a region. This was performed in the open source GRASS GIS software, where we took
‘model’ landslides and dropped them on a 79 km2 test area region in Collazzone, Umbria,
Central Italy, with a given road network (major and minor roads, 404 km in length) and
already determined landslide susceptibilities. Landslide areas (AL) were randomly selected
from a three-parameter inverse gamma probability density function, consisting of a
power-law decay of about –2.4 for medium and large values of AL and an exponential
rollover for small values of AL; the rollover (maximum probability) occurs at about
AL = 400 m.2 The number of landslide areas selected for each triggered event
iteration was chosen to have an average density of 1 landslide km-2, i.e. 79 landslide
areas chosen randomly for each iteration. Landslides were then ‘dropped’ over
the region semi-stochastically: (i) random points were generated across the study
region; (ii) based on the landslide susceptibility map, points were accepted/rejected
based on the probability of a landslide occurring at that location. After a point was
accepted, it was assigned a landslide area (AL) and length to width ratio. Landslide
intersections with roads were then assessed and indices such as the location, number
and size of road blockage recorded. The GRASS-GIS model was performed 1000
times in a Monte-Carlo type simulation. Initial results show that for a landslide
triggering event of 1 landslide km-2 over a 79 km2 region with 404 km of road, the
number of road blockages ranges from 6 to 17, resulting in one road blockage every
24–67 km of roads. The average length of road blocked was 33 m. As we progress
with model development and more sophisticated network analysis, we believe this
semi-stochastic modelling approach will aid civil protection agencies to get a rough
idea for the probability of road network potential damage (road block number and
extent) as the result of different magnitude landslide triggering event scenarios. |
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