Coastal Areas at Risk from Storm Surges and Sea-Level Rise in Northeastern Italy

Abstract

Coastal areas of the northwestern Adriatic Sea, covering a surface of almost 2400 square kilometers along over 300 km of coast between Monfalcone and Cattolica, are depressed below sea level. They are therefore exposed to the risk of flooding by sea surges and rivers. Man-induced or natural subsidence has affected most of these areas, especially near the Po Delta area, where an altitude of over 2.5 m was lost in some places during the past century. In this paper, an assessment is made of near-future relative see-level changes which may occur during the next century, owing to unavoidable additional land subsidence and to the eustatic rise predicted by climatic models. Even in the absence of new human activities triggering land-subsidence processes, the additional loss in land level in relation to sea level is expected to vary by the year 2100 from about 0.5 m near the lagoons of Venice and of Marano-Grado to about 0.6 m near Ravenna and Cervia and to as much as 1.5 m in certain areas of the Po Delta. In a slightly deeper Adriatic Sea, tidal amplitudes will fortunately not increase and sea surges caused by Sirocco winds are not expected to become worse than today; they, however, will develop above locally higher sea levels. Many areas will be more at risk during the next century than today; a few significant case studies, each of them representing specific problems, are analysed: the Ausa-Corno industrial area inland from the Marano-Grado Lagoon, the historic center of the City of Venice, two sample areas in the Po Delta area, and the Ravenna-Ceria area.