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Poster Session
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An application of Remote Sensing techniques in forestry Hazard Monitoring and Damage Estimation
- Estimation of Forest Fire Losses by SPOT and TM Data.
Relatively speaking, using SPOT and TM data to estimate forest fire losses can provide accurate results; due to influence of passing circle, it has relatively low time-effectiveness. For the evaluation of fire losses in large areas, aerial survey of ground inventory has high economic benefits and time-effectiveness, but for small areas, the cost is a little high.
Using Spot and TM data evaluate forest fire losses can obtain the following results: (a) Estimating burned acreage; for example, the acreage of the destructive forest fire in Daxinganling was estimated at 1.265 million hectare which is nearly the same as the result of ground survey; (b). Grading forest fire losses; due to the uneven burning, there is a significant difference in gray scale of spectral reflectance, thus the losses can be classified into 3-5 grades accordingly. In the case of Daxinganling, four grades were identified, and a volume loss in each garage was better estimated by integrating with ground data; (c). Analyzing the correlation between species, landform and loss grade, identifying fire assistant-species, stands and structure, researching on the advantages and disadvantages of different landform to the fire spreading in order to provide data for opening fire lines scientifically and setting up fighting multiple date to find out actual losses and provide trends for natural rehabilitation by species.
In the course of using SPOT and TM data to estimate forest fire losses wee tried to solve following techniques; (a) Deciding optimal synthetic bands in accordance with spectral features; (b). Analyzing relationship between loss status and geographic factors in detail by integrating with GISa (c). Developing techniques for grading fire losses by comarison with forest vegetation distrubution before the fire through full use of complex tecniques of mutiple phase information; (d). Establishing better models that are similar to ground truth survey.
- Forest Wind Damage Assessment by TM Data
In 1986, virgin forest of changbai mountain nature Reserve in Jilin Province was attacked by byg burricane and about tenthousant hecteres of the virgin forests were blown down and 1.85 million cubic meters of growig stock were lost. Due to inconvenient transportation, it was difficult to conduct ground survey. In order to immediately determine the wind damage, TM data was used to estimate the losses and satisfactory results were achieved, which had strongly assisted further proposals. Main subjects of using MT data to assess wind damage are to provide fast and accurate information about losses of acreage and growing stock by combining fewer ground collected information, and landform and relief and transportation status as well.
During the damage estimation, following technical problems had been solved: (a). Extracting wind damage feature. There is a significant difference in color tone between features of vegetation
in wind damaged site and that before the damage; multiple band was synthesized by segmented linear stretching processes; (b). Techniques of damaged area grading. Integrated with GIS, damaged areas were delineated and then were graded, and further were filtered by medium values: (c). Method to estimate growing stock losses of forest trees. Using fewer angle gauge plots on ground, correlation relation was established with imagery, so the growing stock losses was calculated.
Conclusion
Using remote sensing data to monitor forest fire, and to estimate forest disastrous losses is a potential, practicable and economic technical system. Although we have made certain achievement in this area, a lot of more work has to be done on future research and development.
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