PerilAUS II - Relative Risk Ratings for 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

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

Part 1 - Methodology (PerilAUS II) Historical data from PerilAUS I Potential hazards data Step 1 Step 2 Step 3 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

Step 1: Historical data from PerilAUS I (e.g. earthquake) Earthquake MM intensity scale for 1448 affected locations 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.

Potential regions are overlaid with postcode boundaries Medium Low 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

Step 2: Normalisation Conversion: 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). 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 X Very low Very high High-V. high V. low-low Low Medium High Low-medium Medium-high e.g., Bushfire potential with 5 scales

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.

Results e.g. RRR at an ICA Zone level

RRR spreadsheet at a postcode 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)

Distribution of RRR “Total” at a postcode level: 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). e.g. 119.3 (Postcode 800, Darwin) 98.9%

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

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 Flood Bushfire Gust Hail Quake Tornado Landslide Tsunami

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

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

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

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

Natural Hazards Research Centre 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