A new project to monitor land subsidence in the Northern Venice coastland
(Italy)
L. Tosi, L. Carbognin, J. Frankenfield
Institute of Marine Sciences, CNR, Venezia, Italy
P. Teatini
Dept. Mathematical Methods and Models for Scientific
Applications, University of Padova, Padova, Italy
ABSTRACT
The paper deals with the implementation of
a levelling and Global Positioning System (GPS)
network to control land subsidence in the coastal area
north of the Venice Lagoon. About 480 km of levelling
lines with 527 benchmarks, 45 of which suited for
Differential GPS measurements, were established in
2004. A complete survey of the net was carried out in
2004 soon after its establishment. The 2004 records
have been compared with previous scattered data
obtained by the use of levelling surveys, DGPS and
SAR interferometry. The results show a trend in land
settlement that increases from the lagoon margin to the
north and jeopardize the Venice coastland. Groundwater
withdrawals for domestic, agricultural, and health
spas uses, peat oxidation of reclaimed marshlands for
farming, natural consolidation of the Holocene deposits,
and tectonics of the pre-Quaternary basement are
the causes of land subsidence in the study area. Since
most of the area lies below the mean sea level and on
account of the expected sea level rise due to global
change, a detailed monitoring of land displacements in
the near future will be of paramount importance to plan
necessary works for coastland protection.
