PerilAUS II - Relative Risk Ratings for Postcodes and CRESTA/ICA Zones

PerilAUS II- Relative Risk Ratingsfor Postcodes and CRESTA/ICA Zones Part 1: Methodology Part 2: CD-ROM

Background • PerilAUS I CD-ROM(released in October 1999) • Most comprehensive collection of natural perils data 1900-1999 • Searchable database with geo-spatial mapping software • 9 perils • 5,000 events and 10,000 affected locations • PerilAUS II CD-ROM(release in January 2001) • Relative Risk Ratings (RRR) • 2,573 postcodes • 49 CRESTA/ICA Zones • PerilAUS I historical data + additional natural hazards potential • Main concern: Damage to buildings • Approach: Multi-Criteria Evaluation (MCE)-GIS

Balaclava Road Individual dwellings Geographical scales Global States ICA zones Postcodes Street blocks RRR of PerilAUS II deal with two geographical scales:ICA zones and Postcodes

Step 1 Step 2 Step 3 Part 1 - Methodology (PerilAUS II) Historical data from PerilAUS I Potential hazards data Damage index Future perspective Normalisation of scales for each peril Global weighting Peril-by-peril (W1, W2, …, W9) Normalisation of scales for each peril Combination (historical) Combination (potential) Final RRR

Earthquake MM intensity scale for 1448 affected locations Step 1: Historical data from PerilAUS I (e.g. earthquake) Number of affected locations: Bushfire: 941 Earthquake: 1448 Flood: 990 Gust: 1763 Hail: 2984 Landslide: 278 Tornado: 712 T. Cyclone: 877 Tsunami: 74 Total: 10067

Affected locations are overlaid with postcode boundaries For each peril, at a postcode level:  The number of affected locations;  Magnitude or intensity;  Frequency.

Potential hazards data (e.g. bushfire) • Six base maps: • Bushfire • Earthquake • Gust • Hail • T. Cyclone • Tsunami • Derivative maps: buffering zones of historical affected locations: • Flood • Landslide • Tornado Bushfire Potential Source: Johnson et al., (1995). Natural Hazards: their Potential in the Pacific Southwest.

Postcode Low Medium Potential regions are overlaid with postcode boundaries Potential magnitude for the green postcode = Areal averaging (“Low”, “Medium”) Nine potential maps are converted into raster images with the same scale and same coordinate system: Size: 2250 pixels (W-E)  2000 pixels (N-S) Resolution: 2 km Low Medium

Medium-high Low-medium High-V. high Medium High Low 1.0 V. low-low 0.9 0.8 0.7 0.6 Very low Very high 0.5 0.4 0.3 0.2 0.1 e.g., Bushfire potential with 5 scales X 1.0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Step 2: NormalisationConversion: linguistic terms  fuzzy sets  crisp values A numerical approximation system by Chen, S.J. and Hwang, C.L. (1992) with 8 conversion scales. 7th scale contains 9 linguistic terms (left).

Weighting Weighting is to express the relative importance between 9 perils, in terms of damage to buildings (historical and potential) Four sub-factors were assessed using Analytical Hierarchy Process (AHP). The final relative weight for each peril uses their average.

Step 3: Combinations Weighted Linear Combination (WLC)-GIS was used, with five advantages (for details, refer to the PerilAUS II report) (1) Historical component: (2) Potential component: (3) RRR = 30%  (Historical) + 70%  (Potential) Finally, a series of composite maps and spreadsheets at a postcode level and at a CRESTA/ICA zone level are produced.

e.g. Results RRR at an ICA Zone level

Results (contd.) RRR spreadsheet at a postcode level • RRR are comparable and serve as “risk meters”, allowing arithmetic calculations. • (1) Peril-by-peril (horizontally): • Which peril is the most significant? Sub-total risk ratings for perils selected • (2) Postcode-by-postcode (vertically): • individually (9 perils) and collectively • minimum, maximum, average values for easy comparisons • Relative standings (taking the right-hand column “Total” as example, go next slide)

98.9% e.g. 119.3 (Postcode 800, Darwin) Results (contd.) Distribution of RRR “Total” at a postcode level: For the Postcode 800, 98.9% of all 2,573 postcodes have RRR less than 119.3; or only 1.1% of all postcodes have RRR larger than 119.3. In this way, a RRR relative standing spreadsheet can be produced (go next page).

Results (contd.) (previous) RRR spreadsheet at a postcode level New RRR relative standing spreadsheet at a postcode level

Flood Bushfire Gust Hail Quake Tornado Landslide Tsunami Results (contd.) Based on the calculated RRR, while the first three most damaging perils remain the same, RRR values for hails and tornadoes are higher than those from the previous 100 years. Tropical Cyclone

Part 2: PerilAUS II CD-ROM includes: • Spreadsheets (4): • RRR at a postcode level (70 pages) • Relative standing of RRR at a postcode level (70 pages) • RRR at a CRESTA/ICA zone level • Relative standing of RRR at a CRESTA/ICA zone level • Input maps (18): • Historical maps (9) • Potential maps (9) • Output composite maps (6): • Historical composite map at a postcode level • Potential composite map at a postcode level • Final RRR map at a postcode level • Historical composite map at a CRESTA/ICA zone level • Potential composite map at a CRESTA/ICA zone level • Final RRR map at a CRESTA/ICA zone level • Report

PerilAUS II CD-ROM Spreadsheets are provided in .pdf, Excel 97, Access 97 formats Report and maps are provided in .pdf and Word 97 formats - printable, editable, easy data manipulation and conversions

East to browse and locate a postcode using left-pane indexes Spreadsheets - PerilAUS II CD-ROM Summary given at bottom of each page facilitates comparisons

East to browse and locate a map using left-pane indexes Maps - PerilAUS II CD-ROM

Report - RRR of PerilAUS II Detailed methodology and procedures of the RRR development are given in a report

Thank you for viewing the PerilAUS II Demo. To place an order or for more information, please contact: Natural Hazards Research Centre Telephone: +61-2-9850 9683 Fax: +61-2-9850 9394 Email: nhrc@ocs1.ocs.mq.edu.au

PerilAUS II - Relative Risk Ratings for Postcodes and CRESTA/ICA Zones