New approaches to hazard and risk mapping, Vanuatu - developing safer communities

Transcription

1 New approaches to hazard and risk mapping, Vanuatu - developing safer communities David Heron, Biljana Lukovic -, New Zealand Graeme Smart, Doug Ramsay - NIWA, New Zealand Graeme Roberts, Lesley Hopkins Beca International, New Zealand Sylvain Todman Vanuatu Meteorology and Geo-Hazards Department, Vanuatu

2 Part of the boarder Mainstreaming Disaster Risk Reduction Project Funded by Government of Japan through the World Bank Undertaken by the Vanuatu Meteorology and Geo-Hazards Department Contractors were Beca International, and NIWA Commenced Feb 2015 and concluding now

3 Hazards focused on: Earthquake River flood Wind Coastal inundation Tsunami

4 Study areas were: Port Vila and environs

5 Study areas were: Port Vila and environs Luganville and environs

6 Port Vila: Population: 52,000 estimated from census Buildings: 11,650 from PCRAFI database

7 Luganville: Population: 23,000 estimated from census Buildings: 5,145 from PCRAFI database

8 Goals were to: Acquire existing growth, hazard and vulnerability data Develop new hazard and vulnerability information where necessary Model and map urban growth trends, hazards and risks Develop a response to hazards and risks Prepare tsunami evacuation maps

9 What was known: Vanuatu was subject to high levels of hazard

10 What was known: Vanuatu was subject to high levels of hazard What was not known: Which suburbs had the highest hazard and risk Were there areas with lower levels of hazard that could be developed

11 What was known: Vanuatu was subject to high levels of hazard What was not known: Which suburbs had the highest hazard and risk Were there areas with lower levels of hazard that could be developed Because: Previous studies were aggregated to a high level or were intended to inform other issues

12 To be useful for urban planning, hazard and risk information needs to be: at a resolution that allows it to be used to make planning decisions PCRAFI Country Profile

13 To be useful for urban planning, hazard and risk information needs to be: at a resolution that allows it to be used to make planning decisions risk from each hazard should be directly comparable

14 To be useful for urban planning, hazard and risk information needs to be: at a resolution that allows it to be used to make planning decisions risk from each hazard should be directly comparable easily understood GOOD BAD

15 Developing useful hazard information flood:

16 Developing useful hazard information for flood: NIWA modelled flood for Mele Bay and Sarakata River for 10, 50 and 100 year mean return period

17 Developing useful hazard information for flood: NIWA modelled flood for Mele Bay and Sarakata River for 10, 50 and 100 year mean return period Outputs were maximum depth, velocity and flux (depth x velocity)

18 Developing useful hazard information for tsunami:

19 Developing useful hazard information for tsunami: GNS modelled 15 plausible tsunami triggering earthquake scenarios

20 Developing useful hazard information for tsunami: GNS modelled 15 plausible tsunami triggering earthquake scenarios

21 Developing useful hazard information for coastal inundation:

22 Developing useful hazard information for coastal inundation: NIWA modelled exposure zones

23 Developing useful hazard information for coastal inundation: NIWA modelled exposure zones high-tide values developed for 10, 50 and 100 year return periods sea-level for 2013 and predictions for 2030, 2055 and 2090 included

24 Developing useful hazard information for coastal inundation: NIWA modelled exposure zones

25 Developing useful hazard information for wind:

26 Developing useful hazard information for wind: Existing model included crude elevation effect could not be removed Used as was

27 Developing useful hazard information for earthquake:

28 Developing useful hazard information for earthquake: Probabilistic Seismic Hazard Model of Suckale et al 2003.

29 Developing useful hazard information for earthquake: 1. Extend model to other return periods using standard methodology PGA 100 = 0.6 x PGA500 PGA 500 PGA 2500 = 1.46 x PGA500

30 Developing useful hazard information for earthquake: 2. Account for local site conditions: site class

31 Developing useful hazard information for earthquake: 2. Account for local site conditions: site class inferred using geological maps and material descriptions, drill holes, previous studies, geomorphological interpretation of LiDAR

32 Developing useful hazard information: 3. Account for local site conditions: liquefaction

33 Developing useful hazard information: 2. Account for local site conditions: liquefaction susceptibility inferred using geological maps and material descriptions, drill holes, past events, geomorphological interpretation of LiDAR

34 Developing useful hazard information: 4. Account for local site conditions: landslide

35 Developing useful hazard information: 4. Account for local site conditions: landslide inferred from slope derived from LiDAR, including runout zones and collapse zones

36 To be useful for urban planning, hazard and risk information needs to be: at a resolution that allows it to be used to make planning decisions 1: scale maps GIS data

37 To be useful for urban planning, hazard and risk information needs to be: be directly comparable across different hazards Loss from flood at 100 year recurrence interval Loss from earthquake at 100 year recurrence interval

38 To be useful for urban planning, hazard and risk information needs to be: be directly comparable across different hazards

39 To be useful for urban planning, hazard and risk information needs to be: easily understood GOOD BAD

40 Risk Can de defined many ways but typically involves: Hazard severity Assets (buildings, people, anything of value) Vulnerability or Fragility Is present only when there are assets that are vulnerable to a hazard. If there are no assets then RISK = 0 If the assets are not vulnerable to the hazard then RISK = 0 If the hazard is not present or is of low severity then RISK = 0 GOOD BAD

41 Risk For use in planning, risk can not reflect the existing distribution of people and buildings GOOD BAD

42 Risk For use in planning, risk can not reflect the existing distribution of people and buildings GOOD BAD

43 Risk For use in planning, risk can not reflect the existing distribution of people and buildings We developed Potential Risk Maps using an even spread of people and buildings across the entire study area GOOD BAD

44 Risk For use in planning, risk can not reflect the existing distribution of people and buildings We developed Potential Risk Maps using an even spread of people and buildings across the entire study area Loss estimates from all hazards were classified the same way so they could be directly comparable

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50 Under took an Urban Risk Assessment Used: PCRAFI asset database Census GPS data

51 Current risk for Luganville at the 100 year mean return period 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Seismic Flood Wind Coastal Buildings People Buildings People Buildings People Buildings People

52 Current risk for Luganville at the 100 year mean return period 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Seismic Flood Wind Coastal Buildings People Buildings People Buildings People Buildings People

53 Current risk for Luganville at the 100 year mean return period 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Seismic Flood Wind Coastal Buildings People Buildings People Buildings People Buildings People

54 Solutions Land use plans

55 Solutions Land use plans Development controls and standards

56 Solutions Land use plans Development controls and standards Community response

57 Solutions Land use plans Development controls and standards Community response Warning systems

58 Solutions Land use plans Development controls and standards Community response Warning systems

59 Summary Hazards mapped Seismic for 100, 500 and 2500 year mean return periods Flood for 10, 50 and 100 year mean return periods Coastal inundation for 10, 50 and 100 year mean return periods Wind for 50, 100, 250 and 500 year mean return periods Tsunami for 15 plausible worst case events Potential risk maps prepared Combined potential risk map for 100 year mean return period developed Urban risk assessment undertaken Tsunami evacuation maps developed Community consultations undertaken Data and maps available to planners at local scale Recommendations for tools to reduce risk made

60 QUESTIONS AND DISCUSSION?