8/26/2011. Natural Hazards

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1 Support to Local Governments to Imrpove Environmental Management in Southeast Asia August, 011 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 SEVILLO D. DAVID JR., Ph.D. Mines and Geosciences Bureau - DENR North Avenue, Diliman, Quezon City, Floods, landslides hit Leyte By AARON B. RECUENCO March 17, 011, 5:1pm 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 009 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 Cabalawan. 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, 009, 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 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.// Geohazard news. Natural Hazards Guinsaugon, South Leyte, 006 Calamba flood (Milenyo 006) Marikina Flooding (TS Ondoy 009) Compostela Valley, 011 Geologic Setting of the Philippines Philippines Along the Typhoon Belt 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 ~ 0 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 1

2 The Philippines: A geohazards-prone country Guinsaugon Landslide, Southern Leyte, of 006 Numerous active Faults and Trenches Numerous volcanic belts and active volcanoes Generally mountainous terrane and steep 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! Project Objective: DENR-MGB National Geohazards Mapping and Assessment Program 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 5 Project Components: 1. Capacity Building. Data Acquisition, Generation and Integration 3. Conduct of Field Survey 4. Generation of Geohazard maps 5. Information and Education Campaign (IEC) Generation of Geohazard Maps 1 1 FIELD SURVEY 4 LANDSLIDE POTENTIAL = Infrastructures Vegetation map Drainage map Geomorphic map Slope map Geologic map Barangays 8-1 geologists are assigned to comprise the assessment team. The assessment is done at the barangay level

3 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 Brgy. Malangza, Liloan Areas with steep slopes Brgy. Pamigsian, Bontoc STANDARD FIELD DATA SHEET Site interview on flood prone areas and actual investigation of actual flood extent Generation of geohazards map (1:50,000 scale) High landslide Moderate landslide Low landslide Low to moderate flood Areas affected by less than 1 m high flood. These are usually inundated during prolonged and intense rainfall or extreme weather condition. Vigan, Ilocos Sur High flood 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 MODERATE LANDSLIDE SUSCEPTIBILITY POSSIBLE ACCUMULATION ZONE areas likely to be affected by transported landslide materials Flood hazards map of Metro Manila (1:50,000 scale) LOW LANDSIDE SUSCEPTIBILITY 3

4 Coastal Geohazards Impacts of Sea level Change Activities Identification of areas that are vulnerable to coastal geohazards and impacts of sea level changes such as coastal erosion/accretion, coastal inundation, delta subsidence and saltwater intrusion and groundwater quality Comparizon of maps/aerial photos of various dates; Sea bottom topographic survey; DGPS shoreline mapping; 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 CHANGES Coastal Hazard Map ACCRETION EROSION 140 m 760 m 430 m 1300 m STATUS OF GEOHAZARD ASSESSMENT (1:50,000 Scale) MUNICIPALITIES COVERED BY GEOHAZARD ASSESSMENT AS OF END OF DECEMBER % municipalities/ cities assessed (Landslide and flood) Geohazards Assessment and Mapping at 1:50,000 scale At least 385 line km coastal areas assessed for coastal erosion/accretion and coastal flooding Finalized around 90% quadrangle geohazard maps at 1:50, scale 4

5 Detailed Geohazards Assessment and Mapping at 1:10,000 scale 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) 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) Crucial undertaking!!! Landslide Threat Advisory Form Mayors, governors, and other stakeholders are given a copy of the MGB geohazards assessment report RESULTS OF THE MGB RAPID FIELD ASSESSMENT OF LANDSLIDE PRONE BARANGAYS IN STA. CRUZ, LAGUNA Issued to officials of barangays that are susceptible to landslide 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 1, 007 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. Barangay Landslide Recommendations Susceptibility Rating 1. Imok Moderate Report positive findings to MDCC _ Calauan of MGB RO4. 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 ( ASSESSMENT OF FLOOD AND LANDSLIDE EVENTS AND RELOCATION SITES FOR AFFECTED COMMUNITIES (Post Ondoy, Pepeng and Santi) LANDSLIDES AND FLOODS ASSESSMENT RELOCATION SITES ASSESSMENT BAGUIO LA TRINIDAD La Trinidad, Benguet ITOGON TAGUIG Los Banos, Laguna, STA. ROSA 5

6 Setting up of a community-based early warning system for landslides for municipalities/cities highly susceptible to landslides 1. Coordination meetings with LGUs. Conduct of special IEC and OCD re MOA BEFORE DENR-MGB Landslide Warning Signage AFTER 3. Installation of landslide warning signages signages MGB 008 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! MGB Compound, North Ave., Diliman, Quezon City, Philippines Tel/Fax geology@mgb.gov.ph LET S BE READY! 6