Monitoring land subsidence in Semarang City Indonesia using Multiple Acquisition Radar Interferometry (MARI)

摘要

[ABSTRACT]Based on field observation, it was reported that the ground subsidence associated with groundwater extraction became one of environmental problems in Semarang Indonesia. In order to understand time and spatial distribution of land subsidence in Semarang city Indonesia, we performed Multiple Acquisition Radar Interferometry (MARI) of ALOS-PALSAR satellites data. We created 20 interfrogram images from 13 scans SAR data and removed topography phase using DEM three-arcsec (90 m) from each initial interferograms. We performed precision baseline estimation of each pairs to vanish the fringes derived by baseline between master and slave data. The improved phase unwrapping image shows land subsidence about 5-12 cm/y, which mainly caused by groundwater extraction and landuse changing from agriculture and cultivation purposes to industrial estates and house in Semarang. The fringe patterns are detected very clearly in center of Semarang city and northern part of city where the number of pump of groundwater concentrated in this area and large amount of water supply for the communities and industries. Our results are comparable to our previous work and shows the centre of the city was subsided continually after March 2008. The pattern of land subsidence in Semarang city derived by MARI is good relationship with past result obtained by both leveling data and digital elevation modeling (DEM) interpolated and benchmark points.