The Use of Interferometric Spaceborne Radar and GIS to Map Burn Scars and Measure Peat Subsidence in Indonesia

摘要

Interferometric synthetic aperture radar (InSAR) has been increasingly used to monitor ground surface deformations but there have been no investigations into the assessment of peat subsidence caused by drainage and peat fires. The aim of this project is to examine whether differential SAR Interferometry can detect peatland subsidence accurately in Central Kalimantan, Indonesia from March 1996 to December 2000. A methodology is proposed for monitoring ground deformation using multi-pass differential radar interferometry with the aid of a geographic information system (GIS). In this approach, four interferogram were generated from eight ERS1, ERS2 images using four-pass differential InSAR technique to monitor the ground deformations due to peat subsidence. Three subsidence zones were identified and the subsidence rate was about 0-50 mm/year. Coherence has being shown to be a useful concept for system description and for interferogram quality assessment. A change in the interferometric coherence was calculated to map burn scar damage that occurred before and after the fire that happened in 1997. Two coherence change images were computed from these based on different interferograms. Significantly similar results were obtained by identifying burn scars using radar images compared to optical remote sensing data. Coherence values for burn scars of different age show high coherence over the burned forest compared to unburned areas. Future work will focus on determining the degree of burn severity observed by the InSAR. More ground control points (GCP) will be measured in July 2009 using a differential global positioning system (DGPS) in order to improve the accuracy of InSAR derived DEM and displacement maps and for accuracy assessment. This study is of potential benefit to communities outside of Indonesia by expanding the idea to other areas covered by peat soil.