CHALLENGES ON SEDIMENT- RELATED DISASTER MITIGATION

Transcription

1 CHALLENGES ON SEDIMENT- RELATED DISASTER MITIGATION Dolores M. Hipolito Project Manager II DPWH, PMO-FCSEC

2 Types of Sediment-Related Disasters A. Direct Disaster Debris flows Landslides Slope failures Pyroclastic flows B. Indirect Disaster Riverbed aggradation

3 Some Recent Major Sediment Disasters Year Disaster Damages Nov Feb debris flows >1000 people dead and missing, >113,800 houses partially/totally damaged in several municipalities of Albay province Landslide in Guinsaugon, St. Bernard, Leyte 2001 Camiguin flash flood and debris flow A portion of Mt. Kanabag slid and buried the entire community of Guinsaugon 1,132 lives lost 250 people dead and missing; damages to agriculture, infrastructure 1991 Mt. Pinatubo eruption Affected national economy; massive lahar flows damaged wide areas of agricultural lands and buried communities 1991 Flash flood and debris flow in Ormoc City About 8,000 people dead & missing, damages to houses, commercial establishments, etc.

4 Debris Flows in the Towns of Albay Province (Typhoon Reming Nov. 2006) Landslide at Guinsagon, St. Bernard, Leyte (Feb 2006)

5 Features of Disasters in the Philippines Flashfloods, Debris Flows, Landslides, Slope Failures Huge sediment, driftwood and log debris Loss of lives

6 Natural Conditions: Factors of Sediment-Related Disasters a. Typhoons Geographical location along typhoon path 20 typhoons/year, with intense rainfall rain-induced landslides b. Earthquakes Induce landslides that cause massive siltation in river channels c. Volcanic eruptions/explosion of pyroclastic materials Cause rivers to meander and change course Reduce river conveyance capacity

7 Anthropogenic Factors of Sediment- Related Disasters Degradation of Forests Unregulated watershed activities(illegal logging, uncontrolled land development, tillage of sloping areas, etc.) Settlement of people in hazard areas Others e.g., impacts of land use change (change in local hydrology)

8 Anthropogenic Factors Degradation of forests Increases and accelerates surface runoff Erosion and siltation of rivers decreases the conveyance capacity of river channels and water impounding structures

9 Mechanisms of Sediment-Related Disasters insufficient discharge capacity of rivers and weak resistance of slopes against erosion insufficient mitigation measures against floods and sediment disasters insufficient guidance to people for early evacuation insufficient evacuation networks in wider areas access road problems insufficient rescue equipment

10 Main Reasons for Loss of Lives During Disaster Wrong evacuation / No safe evacuation / People do not know what to do Wrong perception of safety behind structural measures Poor knowledge regarding the present danger and hazard / No technical capability No warning / Warning was ignored

11 Low Awareness on Sediment-Related Disasters: Mis-evacuation Leyte Island December 2003 Quezon Province November 2004

12 Hazard and Disaster Damage 82% of damage from disasters is explained by population density and the density of economic activities the magnitude of hazard is responsible for only 7% of damage the effect of disasters is determined primarily by the exposure of people and assets to natural phenomena The best way to avoid disaster is to displace population and activities from disaster-prone areas According to a US study (Choi and Fisher, 2003)

13 Countermessures For Sediment-Related Disaster Mitigation Structural Measures Sabo works Natural slope failure countermeasures Bio-engineering Dredging Non-structural measures Hazard/vulnerability maps Watershed management Monitoring, forecasting and warning system Land use zoning and regulations Information, education and communication programs Evacuation plans

14 What is SABO? SABO( 砂防 ) is a Japanese word SA( 砂 ) means sediment BO( 防 ) means prevention So SABO( 砂防 ) could be translated to prevention of sediment-related disaster. Sabo works are aimed to protect lives, infrastructures, and properties arising from sediment-related disasters in hilly and mountainous terrain.

15 Sabo Dam Sabo dam in Laoag, Ilocos Norte Slit type, Ormoc, Leyte

16 Risk Management of Sediment Related Disasters along National Highways Road Closure Disaster A road closure disaster (road slope failure) is a disaster which causes closure of the whole or partial width of the road (soil collapse, rock slope collapse, landslide, road slips, debris flow, river erosion, coastal erosion) Increasing occurrences losses from reopening costs of roads, loss of lives, detour costs, and damages to electricity, communication and other infrastructures installed along the road

17 COUNTERMEASURES Sediment Disasters Along National Highways Rock Shed Catch Fence Catch Net

18 COUNTERMEASURES Reinforced Embankment (Geo-textile) Bio-engineering (Coco-net) Crib Wall Gabion Wall

19 Non-Structural Measures Reduce the community s vulnerability to the sediment disaster Avert the loss of life Reduce damages to properties Increase community s resilience towards sediment-related disaster Ensure the effect of structural measures to mitigate hazard condition

20 Hazard Maps Source: MGB Camiguin barangay hazard map

21 WARNING!!! Precise knowledge to understand its meaning to avoid panic Enough lead time to induce appropriate reaction Secure to inform the message to all people Warning must be conveyed in an easily understandable manner and in local language through a legally designated single authority. In the dissemination, there should be a tool which is available to poor or far flung people.

22 Public Information, Education and Communication Programs Foster a disaster-aware culture among the identified vulnerable communities. Message delivery mechanisms include primers, comics, posters, pamphlets, TV and radio ads, print ads, messages in movie houses and inclusion of disaster preparedness in school curricula.

23 Public Awareness/Disaster Preparedness/IEC Training of Trainers Community Dialogues Table Top Exercise Evacuation Drill

24 Public Awareness Materials

25 Land Use Planning, Zoning and Regulations Generally determine the distribution of land and type of development for all provinces/municipalities/cities Important in regulating the use of land to prevent encroachment of waterways by illegal settlers Dissuade the settlement of communities in flood plains and in hazard prone areas Determine areas susceptible to slope collapse and sediment-related hazards

26 Overview of Disaster Management Capacity disaster management system needs to be enormously improved there is a critical insufficiency in human resources, technology, equipment, and funding need to take an integrated approach, including establishment of regulations, improvement of institutional system, acquisition of budgets, and promotion of training for professional staff and introduction of equipment

27 Challenges in Sediment Related Disaster Management Increasing protection of communities and properties under threat Improving watershed/river basin management Strengthening institutional and local capacities for flood mitigation Establishing a proper management system of data/information

28 Challenges in Sediment Related Disaster Management Increasing public and private sector awareness and participation Pursuing water and sediment related disaster management Improving enforcement of laws Addressing climate change Good governance

29 Increasing Protection of communities and properties under threat Construction of infrastructures that mitigate the sediment disasters for high risk areas Sabo Dam in Laoag River Budget for maintenance of infrastructures Debris Flow breaker along Kennon Road, Baguio City

30 Improving Watershed/River Basin Management Rehabilitation of watersheds Reforestation Practice of appropriate land cultivation technologies to prevent degradation, erosion and siltation of water bodies Land use plan and zoning considering the hazard prone areas

31 Strengthening Institutional and Local Capacities Human resources development (identification of disaster prone areas, preparation of hazard maps and in the monitoring and warning for evacuation) Introduction of new technologies (high technologies for increased accuracy in forecasting) Provision of logistics such as equipment and budget (increase rain and stream flow stations, disaster management programs)

32 Establishing a Proper Management System of Data/Information Establishing a well-structured information system (characteristics, natural, social and economic conditions, that serve as influential factors contributing to disasters) Updating of topographic maps covering the country at a scale of 1/250,000 Publication of topographic maps of 1/10,000 scale necessary for planning mitigation measures and for preparing hazard maps Increasing the number of rainfall stations and water level stations Updating and managing land use maps

33 Increasing Public and Private Sector Awareness and Participation Community awareness and recognition of dangers in living in hazard prone areas Community involvement in disaster risk management Promotion of education and awareness campaign Improvement of disaster preparedness and response

34 Addressing Climate Change Impacts Philippine Climate Change Scenario Phil. Strategy on CC Adaptation, June 2010 Rise in mean annual temperature by about C to C for 2020; C to C by 2050; Reduction in rainfall in most areas in Mindanao for all seasons by 2050; Increasing trend in the number of tropical cyclones in the Visayas; Decreasing trend in the frequency of tropical cyclones in Mindanao Storm rainfall intensity is likely to increase by 11-20% by 2050 (Cavite Lowland Study, 2008)

35 Countermeasures to Sediment-Related Disasters Combination of Structural & Non-Structural Measures DPWH Role of LGU Role of country Role of people Role of agencies To mitigation of sediment disaster Structural measures Non-structural measures

36 Thank you for your attention!!! Challenges on Sediment-Related Disaster Mitigation