Resolving land subsidence within the Venice Lagoon by persistent scatterer
SAR interferometry
P. Teatini
Dept. Mathematical Methods and Models for Scientific
Applications, University of Padova, Padova, Italy
L. Tosi, L. Carbognin
Istituto per lo Studio della Dinamica delle Grandi Masse, CNR, Venezia,
Italy
T. Strozzi
Gamma Remote Sensing, Muri (BE), Switzerland
G. Cecconi, S. Libardo
Servizio Ingegneria, Consorzio Venezia Nuova, Venice, Italy
R. Rosselli
Sistema Informativo, Magistrato alle Acque di Venezia, Venice, Italy
Land subsidence is a severe geologic hazard threatening the lowlying transitional coastal areas worldwide.
Monitoring land subsidence has been significantly improved over the last decade by space borne
earth observation techniques based on Synthetic Aperture Radar (SAR) interferometry. Within the INLET
Project, funded by Magistrato alle Acque di Venezia - Venice Water Authority (VWA) and Consorzio
Venezia Nuova (CVN), we use Interferometric Point Target Analysis (IPTA) to characterize the ground displacements
within the Venice Lagoon. IPTA measures the movement of backscattering point targets (PTs)
at the ground surface that persistently reflect radar signals emitted by the SAR system at different passes.
For this study 80 ERS-1/2 and 44 ENVISAT SAR scenes recorded from 1992 to 2005 and from 2003 to 2007,
respectively, have been processed. Highly reliable displacement measurements have been detected for
thousands of PTs located on the lagoon margins, along the littorals, in major and small islands, and on
single structures scattered within the lagoon. On the average, land subsidence ranges from less than
1 mm/year to 5 mm/year, with some PTs that exhibit values also larger than 10 mm/year depending
on both the local geologic conditions and the anthropic activities. A network of a few tens of artificial
square trihedral corner reflectors (TCRs) has been established before summer 2007 in order to monitor
land subsidence in the inner lagoon areas where "natural" reflectors completely lack (e.g., on the salt
marshes). The first interferometric results on the TCRs appear very promising.
