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The National Geohazards Mapping and Assessment Program of the Mines and

Support to Local Governments to ImrpoveEnvironmental Management in Southeast Asia

August 22, 2011CSB Hotel, Angelo King International Center, Manila

Geosciences Bureau-Department of Environment and Natural Resources

SEVILLO D. DAVID JR., Ph.D.Mines and Geosciences Bureau - DENR

North Avenue, Diliman, Quezon City,

Geohazard news…….Floods, landslides hit LeyteBy AARON B. RECUENCOMarch 17, 2011, 5:12pmMANILA, 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 nearbyprovinces 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 one of them killed seven members of a family in Barangay

‘Pepeng’ pummels NorthStorm’s return triggers floods; at least 170 deadBy AARON B. RECUENCO, ELENA ABEN, DEXTER SEE. Photo by RIZALDY COMANDAOctober 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.

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 Pangasinanand 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.//

Tacloban City alone, one of them killed seven members of a family in BarangayCabalawan….

Natural Hazards

Calamba flood (Milenyo 2006)Guinsaugon, South Leyte, 2006 Calamba flood (Milenyo 2006)

Compostela Valley, 2011

Marikina Flooding(TS Ondoy 2009)

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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Numerous active Faults and Trenches

Numerous volcanic belts and active volcanoes

Generally mountainous t d t

The Philippines: A geohazards-prone country

terrane and steep slopes

Numerous typhoons and extended rainy seasons/periods

Strong and shifting wave currents

Exacerbated by….Exacerbated by….Silted rivers and, in urban areas, clogged waterwaysSilted rivers and, in urban areas, clogged waterwaysDeforested and denuded forestsDeforested and denuded forestsPOOR SITE SELECTION OF SETTLEMENT SITES!POOR SITE SELECTION OF SETTLEMENT SITES!

Guinsaugon Landslide, Southern Leyte, of 2006

Aims to identify areas in the country that are susceptible

or vulnerable to various

Project Objective:Project Objective:Project Objective:Project Objective:

DENR-MGB National GeohazardsMapping and Assessment Program

or vulnerable to various geologic hazards, and

increase public awareness in order to lessen or mitigate

the negative impacts of these events

5 Project Components:5 Project Components:

1. Capacity Building

2. Data Acquisition, Generation and Integration

3 C d t f Fi ld S3. Conduct of Field Survey

4. Generation of Geohazard maps

5. Information and Education Campaign (IEC)

Vegetation map

Infrastructures

LANDSLIDE POTENTIAL

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Generation of Geohazard MapsGeneration of Geohazard Maps

Geologic map

Slope map

Geomorphic map

Drainage map

Vegetation map

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FIELD SURVEY

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5 6 7 8

2

21 1

1

1

2

2

Barangays

3 33 3

8 -12 geologists are assigned to comprise the assessment team. The assessment is done at the “barangay” level

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STANDARD FIELD DATA SHEET

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

Brgy. Malangza, Liloan

Areas with steep slopes

Brgy. Pamigsian, Bontoc

Areas with drainages that are prone to landslides damming

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

Generation of geohazards map (1:50,000 scale)

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

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. Vigan, Ilocos Sur

HIGH LANDSLIDE SUSCEPTIBILITY

Other examples of geohazard maps (1:50,000 scale)

MODERATE LANDSLIDE SUSCEPTIBILITY

LOW LANDSIDE SUSCEPTIBILITY

POSSIBLE ACCUMULATION ZONE

areas likely to be affected by transported landslide materials

Flood hazards map of Metro Manila(1:50,000 scale)

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Identification of areas that are vulnerable to coastal geohazardsand impacts of sea level changes

Coastal Geohazards – Impacts of Sea level Change

p gsuch as coastal erosion/accretion, coastal inundation, delta subsidence and saltwater intrusion and groundwater quality

Activities

• Comparizon of maps/aerial photos of various dates;

• Sea bottom topographic survey;

• DGPS shoreline mapping;

B h fili / ti• Beach profiling /re-occupation

• Field gathering of evidences of erosion/accretion;

• Gathering of anecdotal accounts

• Mean sea level change (NAMRIA)

• Sediment sampling

• High resolution seismic survey

COASTAL MARGIN CHANGESCOASTAL MARGIN CHANGES

EROSIONACCRETION

140 m

1300 m430 m

760 m

60 4477 9091 02

Coastal Hazard Map

MUNICIPALITIES COVERED BY

GEOHAZARD ASSESSMENT

AS OF END OF DECEMBER 2010

STATUS OF GEOHAZARD ASSESSMENT (1:50,000 Scale)

100% municipalities/ cities assessed (Landslide and flood)

At least 2385 line km coastal areas assessed for coastal erosion/accretion and coastal flooding

Finalized around 90% quadrangle h d t 1 50 000 l

Geohazards Assessment and Mapping at 1:50,000 scale

geohazard maps at 1:50,000 scale

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• DENR-MGB is conducting more detailed geohazardsmapping for highly critical areas.

• Complimented by an early warning thru workshops

Detailed Geohazards Assessment and Mapping at 1:10,000 scale

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)

Making people aware thru

Information and Education Campaign

• 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

La Trinidad, Benguet (with Governor Fongwan)

Landslide ThreatAdvisory Form

Crucial undertaking!!!

Issued to officials of barangays that are susceptible to landslide

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

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 L d lid R d ti

Mayors, governors , and other stakeholders are given a copy of the MGB geohazards assessment report

Barangay LandslideSusceptibility

Rating

Recommendations

1. Imok Moderate Report positive findings to MDCC _ Calauan of MGB – RO4

2. Limao Moderate

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)

Publication of geohazard maps on landslides and floods thru the internet (http://www.mgb.gov.ph)

ASSESSMENT OF FLOOD AND LANDSLIDE EVENTSAND RELOCATION SITES FOR AFFECTED COMMUNITIES

(Post Ondoy, Pepeng and Santi)

BAGUIO

La Trinidad, Benguet

RELOCATION SITES ASSESSMENTLANDSLIDES AND FLOODS ASSESSMENT

LA TRINIDAD

Los Banos, Laguna,

TAGUIGTAGUIG

STA. ROSA

ITOGON

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Setting up of a community-based early warning system for landslides for municipalities/cities highly

susceptible to landslides1. Coordination meetings with LGUs

and OCD re MOA2. Conduct of special IEC

3. Installation of landslide warning signages signages

AFTERBEFORE

DENR-MGB Landslide Warning Signage

Little Kibungan Village in Barangay Puguis, La Trinidad, Benguet , as viewed downslope looking westward BEFORE and AFTER Typhoon Pepeng.

MGB 2008

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

LET’S BE READY!

MABUHAY!www.mgb.gov.ph

MGB Compound, North Ave., Diliman, Quezon City, Philippines

Tel/Fax +63 -2 9288544 Email: geology@mgb.gov.ph