32 Relative Land Subsidence of the Venice Coastland, Italy Luigi Tosi, Pietro Teatini, Tazio Strozzi, and Cristina Da Lio Abstract The Venice coastland, Italy, is an emblematic case of a coastal area prone to progressive submersion by the rising of the sea. Although the city of Venice represents the most relevant case in the northern Adriatic coast, the loss in ground elevation with respect to the sea level, i.e. the relative land subsidence (RLS), is particularly important not only in sectors directly affected by the marine ingression but also in the in-land coastal plain. In this work we quantify the RLS occurred over the period 1992–2010 in the Venice coastland by the superimposition of the Adriatic sea level rise to the ground displacements assessed by the Interferometric Point Target Analysis performed on ERS-1/2 and ENVISAT scenes. Results show that the lowering of certain portions of the coastland relative to the mean sea level amounts to several centimeters, which are values particularly severe for the maintenance and management of the coastal area. Keywords Land subsidence  Relative sea level rise  SAR-based interferometry  Venice coastland 32.1 Introduction The Venice coastland extends along the about 15-km wide and 100-km long strip between the Adige and Tagliamento Rivers. It is formed by a series of estuaries, lagoons and wetlands developed during the prograding phase of the coastline driven by the interaction between eustatic rise and land subsidence during the Holocene sea-level highstand. Today, a large portion of the coastland is composed of reclamation farmlands, which is made of reclaimed low- lying areas, up to 5 m below the mean sea level, estuaries, and the lagoon of Venice. Also minor sea level changes are vital for the survival of this transitional coastal environment. The relative land subsidence (RLS), i.e. the loss in ground elevation with respect to the sea level, is particularly important not only in the city of Venice and in sectors directly affected by the marine ingression but also in the in- land coastal plain. Because of the complex hydraulic setting of the coastlands, RLS severely impacts and increases the L. Tosi (&)  P. Teatini  C. Da Lio Institute of Marine Sciences, National Research Council, Venice, Italy e-mail: luigi.tosi@ismar.cnr.it P. Teatini e-mail: pietro.teatini@unipd.it C. Da Lio e-mail: cristina.dalio@ve.ismar.cnr.it P. Teatini Department of Civil, Architectural and Environmental Engineering, University of Padova, Padova, Italy T. Strozzi GAMMA Remote Sensing AG, Worbstrasse 225, CH-3073 Gümligen, Switzerland e-mail: strozzi@gamma-rs.ch G. Lollino et al. (eds.), Engineering Geology for Society and Territory – Volume 4, DOI: 10.1007/978-3-319-08660-6_32, Ó Springer International Publishing Switzerland 2014 171