Land Subsidence Evaluation Using InSAR Time Series Analysis in Bangkok Metropolitan Area

There has been increasing interest over the last few years in the use of radar interferometry for land subsidence evaluation/monitoring. InSAR time series algorithms such as PSI and small baseline methods offer the possibility to measure ground displacements to a degree of accuracy comparable to traditional geodetic technique such as leveling. This preliminary work reveals the potential of time series analysis to detect more than 300,000 pixels as monitoring points with the maximum subsidence rates roughly 15 mm/year in eastern central Bangkok. The number of monitoring points provided by InSAR is three orders of magnitude greater than those available from the leveling network. The denser and more evenly distributed coherent pixels alleviate an inherent problem of leveling which are spatially biased to accessible areas such as buildings or bridges along major public roads. We generated interferograms from Radarsat-1single look complex images in fine beam mode with DORIS and applied the StaMPS combined PSI and small baseline algorithm. Leveling data of the same period were used to verify the results. In our analysis, we integrated InSAR and leveling data with the same spatial and temporal reference to compare the results and describe the subsidence phenomenon. We find that combining the different characteristics of leveling and InSAR data leads to more efficient monitoring.