Assessing short- and long-time displacements in the Venice coastland by synthetic aperture radar interferometric point target analysis
P. Teatini
Dept. Mathematical Methods and Models for Scientific
Applications, University of Padova, Padova, Italy
T. Strozzi, U. Wegmuller, C. Werner
Gamma Remote Sensing, Muri (BE), Switzerland
L. Tosi, L. Carbognin
Institute of Marine Sciences, CNR, Venezia, Italy
The Venice Lagoon in Italy is a unique environment vulnerable to loss in surface
elevation relative to the mean sea level. We present detailed synthetic aperture
radar (SAR) interferometric analyses on persistent point targets for the
historical center of Venice, the tourist area of Sottomarina, and the Zennare
farmland close to the southern lagoon edge. The selected areas are characterized
by different degrees of development and our analyses show the remarkable
capability of SAR Interferometric Point Target Analysis (IPTA) to map land
displacement rates in densely urbanized zones
and to detect movement information on isolated structures with a mm/year
accuracy. A detailed analysis of the time series from 1992 to 2000 provided by
IPTA shows that the vertical component of the measured displacements are the
superposition of a short timescale, generally seasonal, movement on the order of
1 cm that is likely related to the fluctuation of environmental variables
(temperature, piezometric head in the aquifer
system underlying the lagoon, sea/lagoon water level) and a long-term ground
deformation associated with building construction, the geomorphology of the
area, and the human development of natural resources. If Venice is confirmed to
be generally stable, significant long-term subsidence on the order of 4 mm/year
is detected at the Sottomarina coastland. The highest displacement rates, of up
to 8-10 mm/year, are recorded in the farmland bounding the lagoon margin where
the movements are found to be highly site-specific.
