Monitoring of forest fire damage by using JERS-1 InSAR

The authors investigated on the applicability of interferometric SAR (InSAR) for monitoring forest fire damage. We attempted to use the coherence information obtained through interferometric SAR (InSAR) to detect and monitor damaged areas by forest fire. The test site is the forest around Tamano City in Okayama Prefecture, where a relatively big forest fire occurred in August, 1994, and a total area of 359 ha was burnt. We used several interferometric data pairs by JERS-1 SAR acquired before and after the forest fire. The multilook intensity images and the coherence images were created in the test site and both of intensity and coherence changes due to the fire in damaged forest areas were extracted and they were compared with those in non-damaged forest areas. The result indicated that intensity decreased slightly after the fire, however, the change was not big enough to interpret and extract damaged forest areas clearly. On the other hand, coherence increased significantly in damaged areas after the fire and it was much easier to interpret and extract damaged areas compared with intensity. The experimental result in this study supports that InSAR is effective for detecting and monitoring land cover changes by a forest fire as well as deforestation, for which InSAR has been already verified to use effectively.