Urban subsidence monitoring using radar interferometry: Algorithms and validation

The differential interferometric SAR (DInSAR) technique has proved its capability to detect small surface deformations in several types of applications. In this paper, its use as a quantitative subsidence monitoring too] is addressed to. A complete procedure is described, giving emphasis to the algorithms that have a major impact on the quality of the DInSAR results: the calibration of the InSAR geometry based on ground control points, which guarantees a high accuracy of the InSAR geometric model; a filtering procedure suitable to reduce the atmospheric effects in small-scale subsidences; and a data fusion procedure for multiple observations, which represents a key step to improve the quality of the DInSAR products. The procedure was used in the analysis of a small-scale urban subsidence located in Catalonia, northeastern Spain. The validation of the results, which was based on the comparison with precise and independent reference data, is discussed in detail.