BONDESAN M., ELMI C. & MAROCCO R
Forme e depositi di origine litoranea e lagunare – Forms and deposits of littoral and lagoonal origin
Pages 105-118
Abstract
The Po Plain meets the curving coastline of the Adriatic and runs along it for a distance of almost 330 km. The beaches are gently sloping, alternating with deltas and lagoons. The coast receives its most frequent wave motion mainly from the NE in the Veneto-Friuli sector and from the SE in the Emilia-Romagna sector. The resulting littoral dYl/t thus converges/ its directions are sho!on in fig. 10.1. The dominant wave motion (more violent waves) is generally from E and NE in the Veneto-Emilia-Romagna sector (Zunica) 1971)’ Cati, 1981)’ Calderoni, 1982)’ Idroser, 1982) and ENE to SE in the Friuli sector. In the Adriatic) the main circulation ofwaters) due to tides) is anti-clockwise (fig. 10.1)) with an amphidromic point offAncona. This explains) for example) the fact that the fine sediments coming from the river Po and transported to the sea in suspension are dispersed on the sea bottom in a southerly direction (Nelson) 1970/ Dal Cin, 1983). The mean tidal oscillation is less than 1 m, and is more than sufficient to give rise to strong currents between the sea and the lagoons) and along the main channels of the lagoons themselves (Gottardi & Cauazzoni, 1981). However) when situations of low atmospheric pressure in the northern sector and the Scirocco and sometimes Bora winds overlap with syzigial tides) especially in winter) conditions leading to «high water» occur) sea levels exceeding 1 m above the mean level (exceptionally up to 2 m). These events cause serious difficulties to lagoonal cities like Venice and along other particularly vulnerable stretches of coast) partly because they have become more frequent in the course of time (Pirazzoli, 1974) 1987) 1991) 1993)’ Tomasin, 1974)’ Sbauaglia, 1977)’ Sestini, 1992).
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