Transcript Relative Risk Ratings (RRR) for Postcodes and ICA Zones
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 Postcodes and
Part 1 - Methodology (PerilAUS II)
Step 1
Historical data from PerilAUS I
Step 2
Normalisation of scales for each peril Potential hazards data Damage index Future perspective Global weighting Peril-by-peril (W 1 , W 2 , …, W 9 ) Normalisation of scales for each peril
Step 3
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 Low Medium High Very high
Affected locations within a postcode
For each peril, at a postcode level:
The number of affected locations;
Magnitude or intensity;
Frequency.
Potential hazards data (e.g. bushfire)
Low Moderate High Very high Extreme
Bushfire Potential
Source: Johnson et al., (1995). Natural Hazards: their Potential in the Pacific Southwest.
Six base maps: Bushfire Earthquake Gust Hail T. Cyclone Tsunami Derivative maps : buffering zones of historical affected locations: Flood Landslide Tornado
Potential regions are overlaid with postcode boundaries Low Medium 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
Step 2: Normalisation
Conversion: linguistic terms
fuzzy sets
crisp values
Low Low-medium Medium -high Medium High High-V. high
1.0
V. low-low
0.9
0.8
0.7
0.6
Very low
0.5
0.4
0.3
0.2
0.1
Very high
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
e.g., Bushfire potential with 5 scales Potential scale Low Moderate High Very high Extreme
X
A numerical approximation system by Chen, S.J. and Hwang, C.L. (1992) with 8 conversion scales. 7th scale contains 9 linguistic terms (left).
Linguistic terms
Fuzzy sets
Crisp values Very low Very low – low
[0, 0, 0.2] [0, 0, 0.1, 0.3]
0.0833
0.125
Low Low - medium Medium
[0, 0.2, 0.4] [0.2, 0.35, 0.5] [0.3, 0.5, 0.7]
0.25
0.37
0.50
Medium -high High High – very high Very high
[0.5, 0.65, 0.8] [0.6, 0.8, 1] [0.7, 0.9, 1, 1] [0.8, 1, 1]
0.63
0.75
0.875
0.9167
Linguistic terms
Fuzzy sets
Crisp values Very low – low
[0, 0, 0.1, 0.3]
0.125
Low – medium
[0.2, 0.35, 0.5]
0.37
Medium High Very high
[0.3, 0.5, 0.7] [0.6, 0.8, 1] [0.8, 1, 1]
0.50
0.75
0.9167
Weighting
Weighting is to express the relative importance between 9 perils, in terms of damage to buildings (historical and potential) 35% 30% 25% 20% 15% 10% 5% 0%
T. Cyclone Flood Bushfire Gust
Four sub-factors were assessed using Analytical Hierarchy Process (AHP). The final relative weight for each peril uses their average.
Hail Earthquake Tornado Landslide Tsunami % HE (from PerilAUS I) Area affected Building damage Nationwide importance
Step 3: Combinations
Weighted Linear Combination (WLC)-GIS was used, with five advantages (for details, refer to the PerilAUS II report) (1) Historical component:
H
j n
1
r w j j f j
(2) Potential component:
P
j n
1
r w j j
(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
Historical (30%) + Potential (70%) (49 zones, 15 levels) 0.14 to 0.18 (6) 0.18 to 0.19 (4) 0.19 to 0.2 (3) 0.2 to 0.21 (1) 0.21 to 0.22 (2) 0.22 to 0.26 (6) 0.27 to 0.28 (2) 0.28 to 0.29 (2) 0.29 to 0.3 (1) 0.3 to 0.31 (1) 0.31 to 0.33 (5) 0.33 to 0.34 (5) 0.34 to 0.35 (2) 0.35 to 0.43 (9)
Results (contd.)
RRR spreadsheet at a postcode level Postcode Reference 800
Darwin
2026
Bondi Beach
2072
Gordon
2077
Hornsby
2084
Terry Hills
2135
Strathfield
2140
Homebush
2150
Parramatta … …
MIN MAX AVG Bushfire
0.0
0.0
0.0
32.5
34.5
0.0
0.0
0.0
0 52 15.7
Earthquake
7.9
7.7
7.3
7.3
6.8
7.3
7.8
7.3
1.7
15.6
5.0
Flood
15.3
0.0
9.4
0.0
0.0
33.1
7.1
42.7
0 53 16.3
Gust
11.1
10.4
10.4
10.2
11.6
9.8
7.6
10.3
Hail
9.6
20.3
17.4
18.5
19.5
18.0
18.5
22.1
Landslide
0.0
0.0
1.0
0.4
0.2
0.0
0.0
0.0
Tornado
11.4
11.7
9.8
9.8
9.5
10.1
11.2
12.3
T. Cyclone
62.6
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Tsunami
1.4
0.7
0.0
0.0
0.0
0.0
0.0
0.0
1.4
19.6
4.8
4.8
34.2
11.9
0 6.5
1.4
0 17.1
8.4
0 100 26.5
0 1.5
0.2
Total
119.3
50.9
55.5
78.6
82.1
78.3
52.1
94.7
16.1
162.7
54.8
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)
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).
200 180 160 140 120 100 80 60 40 20 0
98.9%
120% 100% 80% 60% 40% 20% 0% "Total" for a postode
e.g. 119.3 (Postcode 800, Darwin)
Results (contd.)
(previous) RRR spreadsheet at a postcode level
Postcode Reference 800
Darwin … …
MIN MAX AVG Bushfire
0.0
Earthquake
7.9
Flood
15.3
Gust
11.1
Hail
9.6
Landslide
0.0
Tornado
11.4
T. Cyclone
62.6
Tsunami
1.4
Total
119.3
0 52 15.7
1.7
15.6
5.0
0 53 16.3
1.4
19.6
4.8
4.8
34.2
11.9
0 6.5
1.4
0 17.1
8.4
0 100 26.5
0 1.5
0.2
16.1
162.7
54.8
New
RRR relative standing spreadsheet at a postcode level PC Reference 800
Darwin
2026
Bondi Beach
2072
Gordon
2077
Hornsby
2084
Terry Hills
2135
Strathfield
2140
Homebush
2150
Parramatta
…
…
Bushfire Earthquake Flood
0 0 0 95.4
96.3
0 0 0 93.5
91.9
80.2
80.2
58.7
80.2
93.1
80.2
84.2
0 77.7
0 0 93.6
75.2
97.9
Gust Hail Landslide Tornado T. Cyclone Tsunami Total
98.4
9.7
97.5 97.0
94.4 88.8
94.0 93.0
98.7 95.3
93.1 90.4
89.0 93.1
94.2 98.7
0 0 90.3
86.1
84.4
0 0 0 96.2
97.7
73.4
72.5
63.9
84.1
92.9
98.8
99.1
0 0 0 0 0 0 0 99.8
96.2
0 0 0 0 0 0 98.9
53.8
62.1
86.1
88.6
86.0
56.3
94.1
Results (contd.)
35% 30% 25% 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. 20% 15% 10% 5% 0% Tropical Cyclone Flood Bushfire Gust Hail Quake Tornado Landslide Tsunami RRR average nationwide Historical (1900-1999)
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