The impact of relative sea level rise on the Northern Adriatic Sea coast
L. Carbognin, L. Tosi
Istituto per lo Studio della Dinamica delle Grandi Masse, CNR, Venezia,
Italy
P. Teatini
Dept. Mathematical Methods and Models for Scientific
Applications, University of Padova, Padova, Italy
ABSTRACT
The lowlying coast of the Northern Adriatic Sea, between the Venetian territory to the north and
the Ravenna area to the south, is very sensitive to land and sea elevation changes. Subsidence
assessments show that geological land subsidence has and continues to occur unevenly at different
rates (from less than 1 to more than 5 mm/yr), ascribable primarily to sediment compaction and
secondly to deformation of substratum. Anthropogenic subsidence, mainly due to ground-fluid removal, has
severely occurred in the second half of 1900 reaching values of some centimetres in the Venice area
and a few meters southward. Starting in the 1970s, however, with the halt of groundwater
withdrawals, anthropogenic subsidence has been strongly reduced or stopped. The availability of
tide gauge data in Trieste, Venice, and Ravenna, along the Northern Adriatic coast, allows accurate
assessment and meaningful observations of sea level changes. The analysis of data recorded from
1890 to 2007 shows negative trends of relative sea level equal to 1.2 mm/yr in Trieste, 2.5 mm/yr
in Venice, and 8.5 mm/yr in Ravenna. Since Trieste is known to be stable, the rate of 1.2 mm/yr
is attributable to the eustatic rise only. The comparison between Trieste and the other two cities
shows that the trend at Venice and Ravenna is significantly influenced by land subsidence that is
responsible for about the 57% and 85%, respectively, of the recorded relative sea/ground elevation changes.
The relative sea level rise has induced modifications in geomorphologic and ecological features
of the entire coast.
