Presentation on theme: "PerilAUS II - Relative Risk Ratings for Postcodes and CRESTA/ICA Zones"— Presentation transcript:
1PerilAUS II - Relative Risk Ratings for Postcodes and CRESTA/ICA Zones Part 1: Methodology Part 2: CD-ROM
2Background PerilAUS I CD-ROM (released in October 1999) Most comprehensive collection of natural perils dataSearchable database with geo-spatial mapping software9 perils5,000 events and 10,000 affected locationsPerilAUS II CD-ROM (release in January 2001)Relative Risk Ratings (RRR)2,573 postcodes49 CRESTA/ICA ZonesPerilAUS I historical data + additional natural hazards potentialMain concern: Damage to buildingsApproach: Multi-Criteria Evaluation (MCE)-GIS
3Geographical scalesGlobalStatesICAzonesBalaclava RoadIndividual dwellingsPostcodesStreet blocksRRR of PerilAUS II deal with two geographical scales: ICA zones and Postcodes
4Part 1 - Methodology (PerilAUS II) Historical data from PerilAUS IPotential hazardsdataStep 1Step 2Step 3Damage indexFuture perspectiveNormalisation of scales for each perilGlobal weightingPeril-by-peril(W1, W2, …, W9)Normalisation of scales for each perilCombination (historical)Combination(potential)Final RRR
5Step 1: Historical data from PerilAUS I (e.g. earthquake) Earthquake MM intensity scale for 1448 affected locationsNumber of affected locations:Bushfire: 941Earthquake: 1448Flood: 990Gust: 1763Hail: 2984Landslide: 278Tornado: 712T. Cyclone: 877Tsunami: 74Total: 10067
6Affected locations are overlaid with postcode boundaries For each peril,at a postcode level: The number of affected locations; Magnitude or intensity; Frequency.
7Potential hazards data (e.g. bushfire) Six base maps:BushfireEarthquakeGustHailT. CycloneTsunamiDerivative maps: buffering zones of historical affected locations:FloodLandslideTornadoBushfire PotentialSource: Johnson et al., (1995). Natural Hazards:their Potential in the Pacific Southwest.
8Potential regions are overlaid with postcode boundaries MediumLowPotential 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 kmLowMedium
9Step 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).0.10.20.30.22.214.171.124.80.91.0XVery lowVery highHigh-V. highV. low-lowLowMediumHighLow-mediumMedium-highe.g., Bushfire potential with 5 scales
10WeightingWeighting 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.
11Step 3: CombinationsWeighted 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.
13RRR spreadsheet at a postcode level Results (contd.)RRR spreadsheet at a postcode levelRRR 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 collectivelyminimum, maximum, average values for easy comparisonsRelative standings (taking the right-hand column “Total” as example, go next slide)
14Distribution 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 In this way, a RRR relative standing spreadsheet can be produced (go next page).e.g (Postcode 800, Darwin)98.9%
15New RRR relative standing spreadsheet at a postcode level Results (contd.)(previous) RRR spreadsheet at a postcode levelNew RRR relative standing spreadsheet at a postcode level
16Results (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.TropicalCycloneFloodBushfireGustHailQuakeTornadoLandslideTsunami
17Part 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 levelRelative standing of RRR at a CRESTA/ICA zone levelInput maps (18):Historical maps (9)Potential maps (9)Output composite maps (6):Historical composite map at a postcode levelPotential composite map at a postcode levelFinal RRR map at a postcode levelHistorical composite map at a CRESTA/ICA zone levelPotential composite map at a CRESTA/ICA zone levelFinal RRR map at a CRESTA/ICA zone levelReport
18PerilAUS II CD-ROMSpreadsheets are provided in .pdf, Excel 97, Access 97 formatsReport and maps are provided in .pdf and Word 97 formats- printable, editable, easy data manipulation and conversions
19Spreadsheets - PerilAUS II CD-ROM East to browse and locate a postcode using left-pane indexesSummary given at bottom of each page facilitates comparisons
20Maps - PerilAUS II CD-ROM East to browse and locate a map using left-pane indexes
21Report - RRR of PerilAUS II Detailed methodology and procedures of the RRR development are given in a report
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