PSInSAR analysis in urban areas: a case study in the Arno coastal plain (Italy)

The Permanent Scatterer Interferometry (PSI) has been used to detect the land subsidence of the Arno coastal plain, in particular within the urban area of the city of Pisa. Two satellite PSInSAR dataset (ERS 1/2 and Envisat) were used to quantify the spatial evolution of ground displacements. A set of 92 geotechnical borehole was also analyzed to relate the measured displacements with the local stratigraphic asset. Furthermore, the results of the interferometric data analysis were compared with the urban development, from1978 to 2013, of the eastern part of Pisa. The PSInSAR data show that the city of Pisa is divided in two sectors with different subsidence rates: the south - western part, with null or very small movements, and the eastern part that shows a general lowering with maximum velocities of 5 mm/yr. In the eastern part, single or small groups of buildings recorded subsidence rates higher than 15 mm/yr. Through the analysis of the temporal evolution and magnitude of the subsidence rates recorded by several buildings in these areas, the importance of the urbanization as an accelerating factor for the consolidation process have been demonstrated.