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Summary of Proposal LAN0613

TitleEvaluation of Bangkok Land Subsidence using PSI on TerraSAR-X Images
Investigator Trisirisatayawong, Itthi - Chulalongkorn University, Department of Survey Engineering
Team Member
Professor Hanssen, Ramon - Delft University of Technlogy, Department of Earth Observation and Space Systems
Assistant Professor Hooper, Andrew - Delft University of Technlogy, Earth Observation and Space Systems
Mr. Cuenca, Miguel - Delft University of Technlogy, Earth
Mr. Aobphaet, Anuphao - Chulalongkorn University, Survey Engineering
Mr. Keeratikasikorn, Chaipol - Chulalongkorn University, Survey Engineering
SummaryThe research team intends to determine subsidence rates of a study area in Bangkok, Thailand by processing of series of StripMode TerraSAR-X images using SAR interferometry (InSAR) and, in particular, Persistent Scatter InSAR (PSI) methodologies. PSI techniques take advantage of scattering objects (pixels in a image) whose properties remain coherent over time, to measure deformation and height. These pixels can serve as monitoring points, comparable in terms of accuracy to leveling benchmarks but with greater density, thereby alleviating the problems of spatial aliasing and missing small scale subsidence signals resulting from ground water extraction and anthropogenic feature mass load. The 11-day revisit period of TerraSAR-X allows a rapid accumulation of SAR imageries, around 30 images within one year. This rate of acquisition enables the first PSI processing within six months from the first acquisition. The chosen study area is part of Bangkok where intense urbanization and infrastructure developments have been taking place following the opening of Bangkok’s new international airport in 2006. A better PS characterization is expected from the high spatial resolution of TerraSAR-X and this will facilitate the separation of subsidence signals of soft clay ground surface, upon which distributed-load public utilities such as roads, sewage system and pave way reside, from the lower sand layer bearing point load of buildings. Comparison with leveling and GPS data will be made and assessment of the results will be reported to the TerraSAR-X science plan and also in the open literature. The research requires at least 30 TerraSAR-X scenes in StripMap mode (30km width and 50km height), all from the same viewing geometry and same polarization as well as precise orbits of these images. The geodetic coordinates of the image center should be at 13.785oN, 100.715oE. The selected scene coverage (30km width and 50km height) will cover a small part of central Bangkok which is subsiding slowly as well as a significant part of eastern Bangkok where rapid urbanization has been occurring since the opening of the new Bangkok international airport in September 2006. The airport sparked many subsidence-inducing activities such as developments of infrastructure, logistic facilities and housing projects in the once mostly agricultural area. As a result, a complex subsidence pattern is expected in this area. The scene also covers northern part of Samutprakarn province which is a heavily indrustialized area and where there exists only few leveling points. This research will be developed in the framework of GEO2TECDI which is a project aiming to enhance collaboration between European and Thai research institutes. GEO2TECDI is funded by the EU under Thailand-EC Co-operation Facility scheme.

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