#GlendaPH: Know the hazards in your area

Rappler.com
#GlendaPH: Know the hazards in your area
(UPDATED) Here's an official hazard map showing areas along typhoon Glenda's path that are susceptible to storm surges, floods, and landslides

MANILA, Philippines – (UPDATED) Typhoon Glenda (international name Rammasun) is bringing heavy rains across southern Luzon as it inches closer to Metro Manila.

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Glenda is forecast to traverse the National Capital Region and the following provinces:

  • Albay
  • Bataan
  • Batangas
  • Bulacan
  • Camarines Sur
  • Camarines Norte
  • Catanduanes
  • Laguna
  • Nueva Ecija
  • Marinduque
  • Pampanga
  • Pangasinan
  • Quezon
  • Rizal
  • Sorsogon
  • Tarlac 

In a press conference on Monday, the Mines and Geosciences Bureau (MGB) identified 1,117 barangays (villages) in Camarines Norte, Camarines Sur, Catanduanes, Albay, and Sorsogon that are highly susceptible to flooding.

The MGB also said 359 barangays (villages) are highly susceptible to landslide in the same provinces.

Flood Hazard

The map below shows which areas along the storm’s track is susceptible to floods and flashfloods. It is based on shapefiles of hazard maps produced by the MGB, the government agency responsible for the management and development of the country’s mineral resources and lands.

According to MGB Lands Geological Surgery Division OIC Lilian Rollan, the different colors show different levels of danger. People living in different colored areas also need different levels of preparation.

Rollan explained that:

  • Violet areas have high susceptibility to floods. They are usually near bodies of water or prone to flashfloods. According to Rollan, residents in these areas must always be ready to evacuate.
  • Light yellow areas have moderate to low susceptibility to floods. These areas, however, are still vulnerable to “dangerous debris flow.”


Rain-induced landslide hazard

The map on the MGB’s website also indicates areas prone to rain-induced landslides with 3 colors – red, green, yellow. 

Source: http://gdis.denr.gov.ph/mgbviewer/
  • Red areas are highly susceptible to landslides. If a storm passes through a red area, people need to be alert. When water saturates the area, a landslide will likely occur. According to Rollan, people living in red areas should always be ready to evacuate. The longer the rainfall, the more vulnerable the red areas become. Those in red areas are mountains with steep slopes, fractures, and structurally weak rock formations with a history of landslides.
  • Green areas are moderately susceptible to landslides. People living here, however, still need to be cautious. These are usually mountains and rock formations with moderate slopes.
  • Yellow areas are less likely to experience landslides. Landslide debris, however, might still affect the areas as they might possibly become an accumulation zone.

Changing environment

Rollan said the maps are prone to changes as “our environment is not static” – areas identified with low susceptibility can always progress to high susceptibility.

“People should always listen to warnings. MGB always provides advisories to local government units so the map can always be updated,” Rollan added.

The MGB website also gives the following disclaimer:

“The underlying data in this application was compiled from different sources, including Mines and Geosciences Bureau (MGB), and were obtained in different scales, thus accuracy of the geographic features and attributes cannot be guaranteed. Furthermore, the maps included in this application may be subjected to change and/or updates and for visual presentation only and cannot be used for other purposes.”

The resolution of the MGB geohazard map that is currently published on its website is at a scale of 1:50,000.

The bureau is currently working on a higher resolution map at a scale of 1:10,000. They are also creating a map for sinkhole susceptibility. – Rappler.com

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