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In
the wake of the recent tragic mudslides in St. Bernard, Southern
Leyte, PCARRD is advocating the mapping of landslide-prone areas
using the Department of Science and Technology-funded hazard-mapping
study as a model.
Results
of the study showed that landslides could be predicted by using
a geographical information system (GIS)-based hazard map and assessing
the rainfall threshold in areas with heavy rains.
Researchers, Dr. Arturo S. Daag and the late Dr. Norman Tungol of
the Philippine Institute of Volcanology and Seismology (PHIVOLCS)
and Mr. Oscar Cruz and Mr. Maximo Peralta of the Philippine Atmospheric,
Geophysical and Astronomical Services Administration (PAGASA), did
a year-long scientific investigation on the landslides and flashfloods
of December 2003 in Southern Leyte and Northeastern Surigao and
of November 2004 in Quezon province.
They
produced a GIS-based hazard map pinpointing the watershed areas
prone to landslides and flashfloods in the study site. Scenario-based
approximation and simulations quantified the relative danger posed
by the watershed system.
In
studying the chronology of events during the said disasters, the
team was able to establish the rainfall-landslide and rainfall-flashflood
thresholds that triggered the events. Their results established
an extremely high rainfall event with a recurrence period of at
least 50 years.
The
researchers are confident with the high accuracy of the model, which
can be further calibrated and tested so that it can be used to predict
disasters in other landslide-prone areas. (Ma. Rowena M. Baltazar,
S&T Media Service)
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