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1. Analysis objective
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To determine in rough figures the amount of forest land area destroyed by fire.
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2. Analysis procedure Analysis flow chart
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1) Set data of target areas to be analyzed
2) Create images at each observation wavelength
3) Calculate vegetation index values and create images
vi = ((band3-band2)/(band3+band2)+1)*100
4) Determine classification threshold values based on vegetation index values
5) Create disaster condition zone map
6) Estimate size of area lost to fire
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3. Analysis results
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When the pixel size of SPOT-XS data is assumed to be a square of 20m on each side, one pixel covers 0.04ha. Therefore, by multiplying the number of pixels of totally devastated areas by 0.04ha and multiplying the number of pixels of boundary areas between healthy forest and completely destroyed areas by 0.02ha on the assumption that one-half the pixel area was damaged by fire, we attained a total estimated value (137.96ha) for the forest and field land area totally devastated by fire. This figure nearly agreed with the fire-devastated land area (136ha) announced by the Hiroshima Prefecture Fire Fighting and Disaster Prevention Division, which suggests it is possible to use SPOT data for estimating the amount of land area damaged by forest and field fires.
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4.Results from using the analysis results
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In the immediate aftermath of forest fire, a rough estimate of the land area destroyed by fire is more urgently needed than a detailed survey drawing. Although the probability of obtaining excellent data (image) immediately after a calamity strikes is not necessarily high given the observation frequency (optical sensor) at the heart of today's satellite observation systems, it is nevertheless important to prepare a system that can promptly obtain and use good data when we are fortunate enough to obtain it, and to accumulate technical expertise including analytical procedures.
Various information is needed particularly in many of the departments responsible for government administration after the disaster occurs, and there is considerable value to be gained by establishing remote sensing data as one source for gathering timely information.
Use by government administrators
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5. Sources
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Higashi T. and Suga Y.: Practical Use of Remote Sensed Data Transmitting System by using Communication Satellite - Definition of Damaged Area by Forest Fire and Offering Dasaster Information to Forest Conservation Division - , Applied Forest Science, Vol. 9 No. 1, pp. 165-168, 2000
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