Natural Hazards

8/26/2011
Support to Local Governments to Imrpove
Environmental Management in Southeast Asia
August 22, 2011
CSB Hotel, Angelo King International Center, Manila
The National Geohazards Mapping and
Assessment Program of the Mines and
Geosciences Bureau-Department of
Environment and Natural Resources
Floods, landslides hit Leyte
By AARON B. RECUENCO
March 17, 2011, 5:12pm
MANILA, Philippines — At least eight people died while thousands of residents
were forced to flee their homes due to massive flooding and pockets of
landslides that battered Southern Leyte and nearby
provinces in the Visayas and Mindanao, officials said Thursday.
Almost the entire Tacloban City, which is composed of 138 villages, was
submerged in floodwaters that started to rise Wednesday night due to heavy
rains that pounded the area in the morning.
“Practically the entire barangays of Tacloban City are under water, 100 plus
barangays are experiencing flooding. The deepest floodwaters were reported in
northern barangays, the report we received is that the floodwater is neck-deep,”
said Pepz Pabilona, director of the Office of Civil Defense in Region 8 (OCD-8),
or Eastern Visayas.
“It’s like we were hit by ‘Ondoy’ here, it is continuous heavy rains since
yesterday (Wednesday),” said Senior Supt. Wilson Caubat, director of the
Tacloban City Police, referring to the massive flooding that hit Metro Manila in
2009 that left more than 500 people dead.
Caubat said the weather disturbance also caused at least four landslides in
Tacloban City alone
alone, one of them killed seven members of a family in Barangay
Cabalawan….
Geohazard news…….
‘Pepeng’ pummels North
Storm’s return triggers floods; at least 170
dead
By AARON B. RECUENCO, ELENA ABEN, DEXTER SEE.
Photo by RIZALDY COMANDA
October 9, 2009, 4:36pm. Rescuers dig up the 10
persons who were reportedly buried alive after their
houses collapsed at the height of typhoon ‘Pepeng’ on
Friday. But the retrieval operation was stopped due to
the extent of damage in the area.
SEVILLO D. DAVID JR., Ph.D.
Mines and Geosciences Bureau - DENR
North Avenue, Diliman, Quezon City,
Tropical storm “Pepeng” turned back and wrought devastation more than whatt inflicted
during its first visit last week, with over 100 people feared dead in Benguet province
alone from landslides and flashfloods that virtually cut off northern Luzon from the rest of
the country.
Fourteen people were confirmed dead when Pepeng initially pummeled northern Luzon
with strong winds and rains last week. Although it weakened when it revisited the same
areas on Thursday after hovering over the Luzon seas, it brought heavy rains that
caused extensive damage through landslides in Benguet and flooding in Pangasinan
and Nueva Ecija. Data gathered from provincial authorities indicate that as of press
time, the total number of deaths from Pepeng has reached at least 170.//
Natural Hazards
Guinsaugon, South Leyte, 2006
Calamba flood (Milenyo 2006)
Marikina Flooding
(TS Ondoy 2009)
Compostela Valley, 2011
Geologic Setting of the Philippines
The geographic and geologic setting of the Philippines (part
of Pacific Ring of Fire) make it prone to various hazards such
as typhoon/rain-related, volcano-related, earthquake-related
Philippines Along the Typhoon Belt
• ~ 20 tropical cyclones per year enter Philippine Area of Responsibility
• ~ 9 cross the country per year
• heavy rains related to many weather systems – ex. typhoon,
moonsoon, coldfront
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8/26/2011
Guinsaugon Landslide, Southern Leyte, of 2006
The Philippines: A geohazards-prone country
Numerous active Faults
and Trenches
Numerous volcanic
belts and active
volcanoes
Generally mountainous
t
terrane
and
d steep
t
slopes
Numerous typhoons
and extended rainy
seasons/periods
Strong and shifting
wave currents
Exacerbated by….
Silted rivers and, in urban areas, clogged waterways
Deforested and denuded forests
POOR SITE SELECTION OF SETTLEMENT SITES!
DENR-MGB National Geohazards
Mapping and Assessment Program
5 Project Components:
Project Objective:
1.
2.
3
3.
4.
5.
Aims to identify areas in the
country that are susceptible
or vulnerable to various
geologic hazards, and
increase public awareness
in order to lessen or mitigate
the negative impacts of
these events
Capacity Building
Data Acquisition, Generation and Integration
C d t off Fi
Conduct
Field
ld Survey
S
Generation of Geohazard maps
Information and Education Campaign (IEC)
2
Generation of Geohazard Maps
1
FIELD SURVEY
2
2
2
1
4
1
LANDSLIDE POTENTIAL
=
Infrastructures
+
Vegetation map
1
5
+
Drainage map
+
Geomorphic map
+
7
8
Barangays
Slope map
+
Geologic map
6
3
3
3
3
8 -12 geologists are
assigned to comprise
the assessment team.
The assessment is
done at the “barangay”
level
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Basis for the rating of susceptibilities to landslides:
Presence of active and/
or recent landslides
Presence of numerous and
large tension cracks
Brgy. Oslao,
San Francisco,
SDN
Areas with drainages that are prone to
landslides damming
Areas with steep slopes
Brgy.
Malangza,
Liloan
Brgy.
Pamigsian,
Bontoc
STANDARD FIELD DATA SHEET
Generation of geohazards map (1:50,000 scale)
Site interview on flood prone areas and actual
investigation of actual flood extent
High landslide
susceptibility
Moderate landslide
susceptibility
Low landslide
susceptibility
Low to moderate flood
susceptibility
Areas affected by less than 1 m
high flood. These are usually
inundated during prolonged and
intense rainfall or extreme weather
condition.
High flood
susceptibility
Vigan, Ilocos Sur
Areas affected by greater than 1 m
high flood. These areas are usually
flooded for several hours during heavy
rainfalls. Included are landforms of
topographic lows such as active and
abandoned river channels and areas
along river banks.
Other examples of geohazard maps (1:50,000 scale)
HIGH LANDSLIDE
SUSCEPTIBILITY
POSSIBLE ACCUMULATION ZONE
MODERATE LANDSLIDE SUSCEPTIBILITY
areas likely to be affected by
transported landslide materials
Flood hazards map
of Metro Manila
(1:50,000 scale)
LOW LANDSIDE SUSCEPTIBILITY
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Coastal Geohazards – Impacts of Sea level
Change
Identification of areas that are
vulnerable to coastal geohazards
p
of sea level changes
g
and impacts
such as coastal erosion/accretion,
coastal inundation, delta
subsidence and saltwater intrusion
and groundwater quality
COASTAL MARGIN CHANGES
ACCRETION
Activities
• Comparizon of maps/aerial photos
of various dates;
• Sea bottom topographic survey;
• DGPS shoreline mapping;
• Beach
B
h profiling
fili //re-occupation
ti
• Field gathering of evidences of
erosion/accretion;
• Gathering of anecdotal accounts
• Mean sea level change (NAMRIA)
• Sediment sampling
• High resolution seismic survey
Coastal Hazard Map
EROSION
140 m
760 m
430 m
60
1300 m
77
91 90
02
44
STATUS OF GEOHAZARD ASSESSMENT
(1:50,000 Scale)
MUNICIPALITIES COVERED BY
GEOHAZARD ASSESSMENT
AS OF END OF DECEMBER 2010
100% municipalities/ cities
assessed (Landslide and
flood)
At least 2385 line km coastal
areas assessed for coastal
erosion/accretion and coastal
flooding
Geohazards Assessment and
Mapping at 1:50,000 scale
Finalized around 90% quadrangle
geohazard
h
d maps att 1:50,000
1 50 000 scale
l
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Making people aware thru
Information and Education Campaign
Detailed Geohazards Assessment and Mapping
at 1:10,000 scale
• Conduct of on-site briefing for LGUs
• Conduct of lectures/seminars for various stakeholders (e.g.,
mayors, barangay captains, MPDC, PDCC)
• Dissemination of IEC materials (geohazard maps, posters,
CDs, comics)
“Municipal-wide “ IEC
• DENR-MGB is conducting
more detailed geohazards
mapping for highly critical
areas.
• Complimented by an early
warning thru workshops
with critical communities
and piloting of installation of
landslide warning signages
• Issued direct advisories to
LGUs particularly prior to
arrival of typhoons (e.g. TS
Chedeng, Juaning)
La Trinidad, Benguet (with Governor Fongwan)
Mayors, governors , and other stakeholders are given a
copy of the MGB geohazards assessment report
Crucial undertaking!!!
Landslide Threat
Advisory Form
RESULTS OF THE MGB RAPID FIELD ASSESSMENT OF LANDSLIDE PRONE
BARANGAYS IN STA. CRUZ, LAGUNA
In fulfillment of the Mines and Geosciences Bureau (MGB)’s commitment to finish the
geohazard assessment of Laguna province, five (5) geologists from the MGB Central
Office conducted a rapid field assessment of landslide prone barangays in Sta. Cruz on
April 21, 2007
Issued to officials of barangays
that are susceptible to landslide
The rapid field assessment focused on barangays that are located on foot slopes, mid
slopes and mountain ridges. Each barangay was rated with either low, moderate or high
landslide susceptibility.
B
Barangay
1.
2.
Imok
Limao
L d lid
Landslide
Susceptibility
Rating
Moderate
Moderate
R
Recommendations
d ti
Report positive findings to MDCC _
Calauan of MGB – RO4
Monitor progress of mass movement (e.g.
llandslides, tension cracks); Observe for
presence of masss movement (e.g
landslides, tension cracks); Observe for
rapid increase/decrease in creekriver
water levels, possibly accompanied by
increased turbidity (soil content)
ASSESSMENT OF FLOOD AND LANDSLIDE EVENTS
AND RELOCATION SITES FOR AFFECTED COMMUNITIES
(Post Ondoy, Pepeng and Santi)
Publication of geohazard maps on landslides and
floods thru the internet (http://www.mgb.gov.ph)
LANDSLIDES AND FLOODS ASSESSMENT
RELOCATION SITES ASSESSMENT
BAGUIO
LA TRINIDAD
La Trinidad, Benguet
ITOGON
TAGUIG
Los Banos, Laguna,
STA. ROSA
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8/26/2011
Setting up of a community-based early warning
system for landslides for municipalities/cities highly
susceptible to landslides
1. Coordination meetings with LGUs
and OCD re MOA
2. Conduct of special IEC
BEFORE
AFTER
DENR-MGB Landslide Warning Signage
3. Installation of landslide warning signages signages
MGB 2008
Little Kibungan Village in Barangay Puguis, La Trinidad, Benguet , as viewed
downslope looking westward BEFORE and AFTER Typhoon Pepeng.
REMARKS
INCREASE AWARENESS OF WHAT HAZARDS ARE
PRESENT IN THE COMMUNITY
FAMILIARIZE ON THE EARLY WARNING SIGNS FOR
THE VARIOUS GEOHAZARDS
MAXIMIZE UTILIZATION OF INFORMATION ON
GEOHAZARDS FOR DEVELOPMENT AND LAND USE
PLANNING
MABUHAY!
www.mgb.gov.ph
MGB Compound, North Ave., Diliman, Quezon
City, Philippines
Tel/Fax +63 -2 9288544
Email: geology@mgb.gov.ph
LET’S BE READY!
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