Multi-temporal mapping of land subsidence at basin scale exploiting Persistent Scatterer Interferometry: case study of Gioia Tauro plain (Italy)

The temporal and spatial evolution of the pumping-induced ground subsidence in the Gioia Tauro plain (Southern Italy) is investigated exploiting multi-temporal analysis of PSInSAR (Permanent Scatterer Interferometric Synthetic Aperture Radar) data from ERS 1/2 (1992–2001) and ENVISAT (2002–2006) satellites. The PSInSAR derived ground deformation velocity maps and related displacement time series reveal that subsidence rates as high as 10–15 mm/yr are observed in 1992–2006, with the highest velocities (up to 23 mm/yr) occurring between 1992 and 2000 in the central portion of the Plain. Ascending and descending data are combined to extract the vertical and east-west components of ground motions, and reveal the presence of predominant components in the vertical direction due to the compaction of Quaternary sediment in the basin. Aquifer compaction is a consequence of groundwater abstraction. An acceleration index is computed to synthesize the temporal changes between the observed displacements in the two intervals, 1992–2001 and 2002–2006. Deceleration of motions is observed in most of the plain with velocity reductions of about 65% from 1992–2001 to 2002–2006; only a few narrow areas in the southern sector reveal significant increases of motion velocities in the 2002–2006 period, with subsidence velocities exceeding by about 30% those observed in 1992–200