MONITORING OF DEFORESTATION IN TROPICAL RAIN FOREST AREAS BY USING INSAR - COMPARISON BETWEEN L-BAND AND C-BAND SAR -

摘要

The author compared the capability of coherence information obtained from interferometric SAR (InSAR) by C-band SAR of ERS-1 and 2 and by L-band SAR of JERS-1 for the purpose of monitoring the changes of tropical rain forest due to deforestation. The test site was a southern part of Sumatra Island with 50 by 50 kilometers coverage. The several repeat-pass interferometric data pairs by JERS-1 and ERS-2 acquired from 1996 to 1998 were used to compare the coherence patterns between L-band and C-band SAR. In addition, two tandem pairs by ERS-1 and 2 were used to compare the coherence patterns between repeat-pass and tandem pairs of C-band SAR. The result indicated that the coherence obtained from ERS repeat-pass pairs was almost useless due to its extremely poor quality. On the other hand, the coherence obtained from JERS-1 repeat-pass pairs was proved to be useful for identifying the deforested areas together with the coherence obtained from ERS tandem pairs. The performances for land cover classification with the combined use of intensity and coherence were also compared among JERS-1 repeat-pass, ERS repeat-pass, and ERS tandem data pairs. The result indicated that the classification accuracy for deforested areas was significantly improved by combining coherence with intensity for JERS-1 repeat-pass and ERS tandem pairs. On the other hand, ERS repeat-pass resulted in almost no improvement even by the combination of intensity and coherence. The result of this study strongly suggests the usefulness and the importance of the repeat-pass interferometry by L-band SAR like ALOS/PALSAR for the purpose of monitoring tropical rain forest changes.