Natural Hazards
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8/26/2011 Support to Local Governments to Imrpove Floods, landslides hit Leyte Geohazard news……. Environmental Management in Southeast Asia By AARON B. RECUENCO August 22, 2011 March 17, 2011, 5:12pm MANILA, Philippines — At least eight people died while thousands of residents CSB Hotel, Angelo King International Center, Manila 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 The National Geohazards Mapping and 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. Assessment Program of the Mines and 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 Geosciences Bureau-Department of Cabalawan…. ‘Pepeng’ pummels North Environment and Natural Resources 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. 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 SEVILLO D. DAVID JR., Ph.D. the country. Fourteen people were confirmed dead when Pepeng initially pummeled northern Luzon Mines and Geosciences Bureau - DENR 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 North Avenue, Diliman, Quezon City, 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 Philippines Along the Typhoon Belt • ~ 20 tropical cyclones per year enter Philippine Area of Responsibility • ~ 9 cross the country per year The geographic and geologic setting of the Philippines (part • heavy rains related to many weather systems – ex. typhoon, of Pacific Ring of Fire) make it prone to various hazards such moonsoon, coldfront as typhoon/rain-related, volcano-related, earthquake-related 1 8/26/2011 The Philippines: A geohazards-prone country Guinsaugon Landslide, Southern Leyte, of 2006 Numerous active Faults and Trenches Numerous volcanic belts and active volcanoes Generally mountainous terrane andtd 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! DENR-MGB National Geohazards Mapping and Assessment Program 5 Project Components: Project Objective: Aims to identify areas in the 1. Capacity Building country that are susceptible 2. Data Acquisition, Generation and Integration or vulnerable to various 3. CdtfFildSConduct of Field Survey geologic hazards, and increase public awareness 4. Generation of Geohazard maps in order to lessen or mitigate 5. Information and Education Campaign (IEC) the negative impacts of these events 2 Generation of Geohazard Maps 2 FIELD SURVEY 1 1 2 2 4 1 LANDSLIDE POTENTIAL = 1 Infrastructures 5678 + Vegetation map + Drainage map Barangays + Geomorphic map + 8 -12 geologists are Slope map assigned to comprise + the assessment team. The assessment is Geologic map 3 3 3 3 done at the “barangay” level 2 8/26/2011 Basis for the rating of susceptibilities to landslides: Presence of active and/ Presence of numerous and or recent landslides large tension cracks Brgy. Oslao, San Francisco, SDN Areas with drainages that are prone to landslides damming Areas with steep slopes Brgy. Malangza, Brgy. Liloan 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 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 Vigan, Ilocos Sur along river banks. Other examples of geohazard maps (1:50,000 scale) HIGH LANDSLIDE SUSCEPTIBILITY Flood hazards map of Metro Manila POSSIBLE ACCUMULATION ZONE areas likely to be affected by MODERATE LANDSLIDE SUSCEPTIBILITY transported landslide materials (1:50,000 scale) LOW LANDSIDE SUSCEPTIBILITY 3 8/26/2011 Coastal Geohazards – Impacts of Sea level Activities Change • Comparizon of maps/aerial photos of various dates; Identification of areas that are • Sea bottom topographic survey; vulnerable to coastal geohazards • DGPS shoreline mapping; and impacts of sea level changes • Beac h pro filing /re-occupation such as coastal erosion/accretion, coastal inundation, delta • Field gathering of evidences of subsidence and saltwater intrusion erosion/accretion; and groundwater quality • 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 607791 90 02 44 STATUS OF GEOHAZARD ASSESSMENT (1:50,000 Scale) MUNICIPALITIES COVERED BY GEOHAZARD ASSESSMENT AS OF END OF DECEMBER 2010 Geohazards Assessment and 100% municipalities/ cities Mapping at 1:50,000 scale assessed (Landslide and flood) Finalized around 90% quadrangle geohdhazard maps at 1: 50, 000 sca le At least 2385 line km coastal areas assessed for coastal erosion/accretion and coastal flooding 4 8/26/2011 Detailed Geohazards Assessment and Mapping Making people aware thru at 1:10,000 scale Information and Education Campaign • DENR-MGB is conducting • Conduct of on-site briefing for LGUs • Conduct of lectures/seminars for various stakeholders (e.g., more detailed geohazards mayors, barangay captains, MPDC, PDCC) mapping for highly critical • Dissemination of IEC materials (geohazard maps, posters, areas. CDs, comics) • Complimented by an early “Municipal-wide “ IEC 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) Crucial undertaking!!! Mayors, governors , and other stakeholders are given a copy of the MGB geohazards assessment report Landslide Threat RESULTS OF THE MGB RAPID FIELD ASSESSMENT OF LANDSLIDE PRONE Advisory Form 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 Issued to officials of barangays Office conducted a rapid field assessment of landslide prone barangays in Sta. Cruz on that are susceptible to landslide 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. Barangay Lan ds lide RdtiRecommendations Susceptibility Rating 1. Imok Moderate 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 2. Limao Moderate 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 Publication of geohazard maps on landslides and floods thru the internet (http://www.mgb.gov.ph) (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 8/26/2011 Setting up of a community-based early warning system for landslides for municipalities/cities highly BEFORE AFTER susceptible to landslides 1. Coordination meetings with LGUs 2. Conduct of special IEC DENR-MGB Landslide Warning Signage and OCD re MOA 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 MABUHAY! FAMILIARIZE ON THE EARLY WARNING SIGNS FOR THE VARIOUS GEOHAZARDS www.mgb.gov.ph MGB Compound, North Ave., Diliman, Quezon MAXIMIZE UTILIZATION OF INFORMATION ON City, Philippines GEOHAZARDS FOR DEVELOPMENT AND LAND USE Tel/Fax +63 -2 9288544 PLANNING Email: [email protected] LET’S BE READY! 6.