Derivation of surface subsidence information in Bangkok (Thailand) by PS analysis of a limited number of interferograms

We used Persistent Scatterer Interferometry (PSI) to quantify surface subsidence in the Bangkok Metropolitan area with 20 ERS-1/2 acquisitions. Strong atmospheric influence and limited number of images presented the main challenges in this study. Despite these difficulties, our results have shown that we can obtain subsidence estimates with millimetric precision. By validation with independent leveling data, we show that the achievable precision at locations subsiding at approximately constant rates is better than □ 1.5 mm/y. The discrepancy between PS estimates and the reference leveling increases as the degree of temporal variability of subsidence rates increases. At 6 out of 10 investigated benchmarks the PS-derived subsidence rate estimates agreed better than □ 1.5 mm/y with the benchmark values. However, compared to benchmark leveling spatially varying subsidence field can be characterized much better from subsidence estimates from PS. The PS density of 28 PS/km² makes our PS subsidence map the most detailed subsidence information of Bangkok to date.