An application of Remote Sensing techniques in forestry Hazard Monitoring and Damage Estimation
Li Liuyu, Kou Wenzheng, Cao Xufeng, Long Jing
Academy of orest Inventory and Planning Ministry of Forestry,
Beijing, China
Abstract
This article describes the techniques and experiences of using Meterological Satellite, Thematic Mapper (TM) and Spot data to monitor forest fire and assess its damages caused by fire and wind hazards; lists advantages and disadvantages in using the data and technical fields to be solved, and explores the developing trends of such methods; presents actual application status and results by examples of the destructive forest fire occurred in Daxinganling and wind hazard in Changbai Mountain in 1987 and 1986 separately in China, and clearly indicates the possibilities of using such information and methods.
Introduction
It is known that forests are important biological resources with multiple benefits in econo ics, society and ecology, and play a key role in keeping the global ecological balance. It is our fundamental policy to reserve, develop and use our forest resources in China, Afforestation Has been actively carried out in large scale and much has been done in preserving existing forest resources, which have contributed greatly to keeping the global ecological balances. However, due to the long growing circle, forests are constantly attacked by diferent kinds of hazards under the effects of natural stresses and human activities. In order to effectively protect existing forest resources, active and effective methods must be adopted to monitor the occurrences and spreading of various forest hazards and assess te damages accordingly so as to timely control its occurrences and development, to summarize the experiences and the minimize the losses. Over a decade, based on our traditional hazard monitoring method, we have applied remote sensing techniques to accomplish the monitoring mission.
Application of Remote Sensing techniques to Monitoring forest fire
Fires are the worst hazard for forest resources. It not only causes the losses of forest and property, but also severely destroys ecological environment. In order to implement the forest fire control policy of early suppression, we have actively developed and applied the forest fire monitoring techniques using meteorological satellite data since 1985, it had played an important role in fire fighting in the destructive forest fire in Daxinganling which happened on May 6th of 1987. Using Meterological Satellite information to monitor forest fire not only has features of large ground coverage and timely warming of fire occurrences (especially in inaccessible forest areas in which other monitoring means can not be fully established), but also obtains a whole set of data on the occurrences and expanding of forest fires, which provide accurate and timely in formation in organizing fire suppression and spreading. Meteorological Satellite data applied in forest fire monitoring has demonstrated advantages of high sensitiveness, time-effectiveness and low cost.
During the research of using meterological Satellite data to monitor forest fires, we have mainly explored the following technical areas.
- Time-effectiveness of Meteorological Satellite Information in Forest fire Monitoring
Forest fire is characterized by sudden occurrence, and fire control agencies want to have warning information as early as possible. Existing NOAA satellite passes China's territory every four hours. Since the fire occurring possibility is low in cloudy and rainy weather, cloud cover can both bring a substantial impact on forest fire monitoring. Statistics made from over a hundred cases of occurrences and expanding of forest fire have showed that the time span by using Meteorological Satellite to monitor forest fire is 2-4 hours and its accuracy is a little higher than that of air patrolling, and lower than that of human patrol within the visibility on ground. Therefore it is concluded that the time-effectiveness is acceptable by using NOAA-2, which is operating, in space in forest fire monitoring. After the destructive forest fire in Daxinganling in 1987, another ten small fires happened within the region, of which four were detected by Meteorological Satellite ahead of ground methods six were ahead of air plane and two were in the same time as air plane and ground patrols.
- Sensitiveness of meteorological Satellite to forest fires
Theoretically the temperature resolving power of sensors in Meteorological Satellite is 0.1k, and spatial resolution is 1100m. Temperature resolving power can totally meet the requirement of forest fire monitoring, and spatial resolution is much lower, however if the two are combined, and feature extracting techniques are adopted, the requirement can also be met Taking the destructive forest fire in Daxinganling as an example again, all burning sites that were over one hectare in the ten events were detected by Meteorological Satellite. Although burning areas were small, the effect of released heat energy were far beyond the actual burned area resulting in temperature raises in relatively large areas and were reflected in Metrological Satellite imagery. Evidently, to fully develop temperature sensitiveness of Meteorological Satellite imagery. Evident, to fully develop temperature sensitiveness of Meteorological Satellite to better forest fire monitoring, attention must be paid to the functions of middle inferred band, and adoption of proper synthesis of three bands and feature stretching method. Our research has indicated that forest fire about half hectare in size can be detected by using Meteorological Satellite.
