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Methodology to integrate hyperspectral Remote Sensor data with GIS for decision support systems:- A case of hail storm damage in Sydney
Sunil Bhaskaran, Bruce Forster
School of Surveying and Spatial Information Systems
Faculty of Engineering,University of New South Wales
Sydney, 2052, NSW, Australia.
Trevor Neal
Corporate Strategy Division, New South
Wales Fire Brigades,Sydney,
2000,NSW, Australia.
Introduction
Hail storms can result in substantial damage to property throughout the world. In Sydney, Australia for instance on the 14th April 1999, a thunderstorm was detected forming approximately 115 km south of Sydney near Nowra. In a span of 25 minutes the storm unleashed a maelstrom of icy fury, as the largest hailstones ever recorded in Sydney crashed down from the skies at over 200 km/h. The storm carved a path of destruction resulting in an estimated damage bill of 1.5 billion dollars (Fire News, 1999). Historically hailstorms have contributed to huge losses of property and in some rare instances lives. Table xxx shows the total estimated financial losses incurred by hail storms and other catastrophies from 1967-1998.
While the prevention of hailstorm is a myth, the management of dynamic resources for rescue and post disaster operations is an important issue. Hail storms result in damaged roofs, windows, temporary flooding, electrical short circuit, outbreak of fire, and general panic among residents. There is a high correlation of damaged roofs to the material composition of the roofing material which in turn determines their resistance to sustain the onslaught and fury of hail stones Andrew and Blong (1997a), Vorobief et al., n.d. Under these circumstances a systematic approach to the problem of rescue and repair operations hinge on a multitude of spatio-temporal geographic data. For instance, prior knowledge of areas with higher susceptibility which in this case may be explained by the types of roofing materials is vital for the allocation of dynamic resources. A clear and precise idea about the target areas which are likely to be affected by hailstones is necessary in order to manage post disaster operations efficiently (Sunil et al, 2000). This study examines the potential of a spectral analysis of urban surface materials including roofing materials which may provide some geographic details to the emergency services for strategic resource allocation and decision support .
Table 1 Largest Australian Insured Catastrophic Losses 1967-1998 Insurance Council of Australia
| Event |
Location |
Date |
Insured Loss
(A$ million) |
| Earthquake |
Newcastle |
1989 |
1125 |
| Cyclone Tracy |
Darwin |
1975 |
835 |
| Hailstorm |
Sydney |
1990 |
385 |
| Cyclone Wanda |
Brisbane |
1974 |
330 |
| Bushfires |
Victoria/
South Australia |
1983 |
325 |
| Hailstorm |
Brisbane |
1985 |
300 |
| Thunderstorm |
Sydney |
1991 |
225 |
| Hailstorm |
Sydney |
1986 |
160 |
| Hailstorm |
NSW |
1976 |
130 |
| Cyclone Madge |
Northern Australia |
1973 |
150 |
| Cyclone Althea |
Townsville |
1971 |
150 |
Current information about the vulnerable portions of the city of Sydney is vital for emergency preparedness. Hailstorm vulnerability can be assessed by the type of roofing material used for houses and other structures since different roofing materials have varying degrees of resistance to hail stones. The roof is the first point of impact from the hailstorm and thereafter severe damage is caused to the houses and property. Various studies indicate that tiles, gutters, windows, brittle cladding materials and metal sheeting are all at risk during heavy hail. Thin metal sheeting is dented or even penetrated, while tiles develop hairline cracks and are often shattered under the impact of hail stones. Age and impact location are important factors for many roofing materials (Vorobief et al., n.d). A study carried out by Andrew and Blong (1997b) reported that tile roofs were the most commonly damaged roof type. The study ranked roof materials were in decreasing order of susceptibility to damage: aluminium, fibro, slate, tiles and iron. Roofs contributed as one of the major cost items accounting for 22% of the total cost. The degree of resistances of roofing materials vary according to the material composition and these roofs are distributed in varying proportions over the Sydney metropolitan region which may be hit by hail storms in the future.
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