GIS & Natural Hazards

Transcription

1 GIS & Natural Hazards John McAneney Risk Frontiers 1 mm 10 mm 100 mm 1000 mm mm kilometres

2 Risk Frontiers An independent and local research capability to: help insurers and reinsurers better understand and price natural hazard risks in the Asia-Pacific region develop Probabilistic Catastrophe Models undertake research in natural hazards undertake post-event reconnaissance increase public awareness of natural perils Sponsors Swiss Re, IAG, Suncorp Group, QBE, Aon Benfield Guy Carpenter, Australian Re Pool Corporation

3 Risk Risk In an insurance context: risk is well-defined: annual exceedance probability of an event loss greater than $X Atlantic Ocean In wider usage, risk becomes more nebulous even experts use the concept in many different ways P bli d t i i k diff tl d i h Public and experts view risks differently and may weigh decision options differently

4 Conceptual framework of risk assessment Risk = f (Hazard, Exposure, Vulnerability) Hazard Mean damage ra atio (%) Mean intensity Annual E xceedance Probability Exposure Vulnerability Loss ($ Million) Risk

5 Tokyo Volcanic Tephra Fall Risk

6 Nankai Subduction Zone Earthquake Mw = 8.1, ARI = 90 years

7 Australian Flood risk Overlay Analysis Digital Terrain Model Flood Surfaces Module Street Address Module Inundation depth ARI = DTM - flood surface ARI

8 Grafton, flood surface with and without levee

9 Coastal Vulnerability in NSW Used very high-resolution geospatial data sets to investigate how exposures (e.g., addresses and population) are distributed in relation to distances from shorelines and elevation above mean sea level, i.e., Aggregate Exposure = f (Distance, Elevation) Examined this at various levels: - The Greater Sydney region - Entire NSW coasts - Results disaggregated for individual LGAs RISK FRONTIERS

10 High-resolution inputs (1) Shoreline (1:4K scale) (2) 5m-resolution DTM (3) Location of addresses (G-NAF) Maroubra Beach

11 Address-based coastal vulnerability database Attributes Address / Postcode / Locality / - distance to shorelines - elevation RISK FRONTIERS

12 Distribution patterns of most at-risk addresses Distance: <3km Elevation: <3m Lake Narrabeen Double Bay Plaza Kurnell Bundeena RISK FRONTIERS

13 At-risk addresses (<3km of shorelines & elevation <3m) Pittwater Woollahra Rockdale Sutherland Shire Number of addresses Distance < 3km and Elevation < 3m 3,060 to 4,490 (2) 1,130 to 3,060 (3) 190 to 1,130 (10) 30 to 190 (10) 0 to 30 (4) (a) Absolute (b) Percentage % % of addresses Distance < 3km and Elevation < 3m 6 to 10.1 (3) 1.4 to 6 (10) 0.4 to 1.4 (4) 0.2 to 0.4 (2) 0 to 0.2 (10)

14 Detailed examination for individual beaches using high-resolution inputs. <2m 3-6m 2-3m Kurnell, Sydney y RISK FRONTIERS

15 Extrapolation for large areas: Comparing 5m-resolution DTM and 90m-resolution SRTM (NASA) or the Sydney Basin 5m-resolution DTM (coverage limited) 90m-resolution SRTM (Near global coverage) RISK FRONTIERS

16 Bushfire: Blue Mountains

17 Bushfire: Duffy Pre-fire: Post-fire: 25/06/ /01/2003 QuickBird Image: 0.6m (PAN), 2.4m (multispectral)

18 Bushfire: Marysville post-fire Aerial Photography 15 cm resolution (Airtech)

19 Marysville Digitizing destruction

20 Pre-fire bushland boundaries by Image Classification Yellow dots: buildings with distance to bushland less than 10m Spot Fire Imagery 2.5 m resolution

21 Post-Event reconnaissance: 26 December 2004 Sumatra Earthquake & Tsunami

22 Centre Ville

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24 Hazard maps: 475 Yr Tsunami Exceedance Heights for the NE Indian Ocean Due to Earthquakes along the Sumatran-Andaman Subduction Zone

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26 Travel Times 475 ARI wave height - Galle

27 Travel Times 475 ARI wave height - Meulaboh

28 Ulee Lheue

29 Reality in Sumatra Short evacuation times ~ 10 to 20 minutes Severe ground shaking ~ 5-7 minutes In many places there is no accessible high ground Women s athletics world record for 5 km run is ~ 14.2 min Only real solution is land planning that stops people living close to sea but this is probably impractical Tsunami risk is not going g to stop people e living in Meulaboh and Banda Aceh Faced with this disaster being repeated again in future

30 Reducing society s vulnerability to natural perils Will require hard decisions that we have mostly avoided til now Insurance premiums will become increasingly gy linked to actual risk Need better land planning decisions Good American [Australian] land planning principles are based upon property p owners right to build what they want, and the government s obligation to bail them out afterward. (Washington Post: September 21.)

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