Polesine

[2] The eastern portion of Polesine corresponds to the delta of the Po, and it is constantly expanding eastward because of the detritus sediment phenomenon.

After the fall of Rome and the disasters in the hydrography of the whole Veneto, traditionally referred to as the breach at Cucca in 589, Adria and its port lost their significance.

In 1152, another disaster changed the hydrography of Polesine: a breach opened in the banks of the Po at Ficarolo and the new main course started flowing much closer to the Adige.

All these areas established the Territory of Polesine inside the Domini di Terraferma (Mainland State) of the Republic of Venice.

The main floods had been: Actual Polesine territory is, geologically speaking, of recent formation, created by drifts taken by rivers Po and Adige, and subsequently from human modifications.

Contemporary to the rising of Alps and Apennine Mountains, the entire Padania was filled by a long inlet (the Adriatic depression) and the seabed of this huge ditch was full of troughs and elevations.

Floods frequently happened in Polesine filled the depressions of the area with several bundles of sediments consisting in sand, clay and silt.

This map highlights the location of what is nowadays Polesine in Italy.
Progression of Polesine since 1484. Yellow area is the Territory of Polesine established in 1484 inside the Mainland State of the Republic of Venice after the War of Ferrara; red area is part of the lands that had been detached from the Papal States and was annexed to Polesine in 1815 to establish the Provincie of Rovigo inside the Kingdom of Lombardy–Venetia; greenish area is the other part of the lands that had been detached from the Papal States in 1815 but at first was annexed to the Province of Venice inside the Kingdom of Lombardy–Venetia; green and greenish areas together were detached in 1851 from the Province of Venice and annexed to the Province of Rovigo. Lighter land has recent formation, roughly from 1604 onwards.
Polesine (located at the north-east in this map) and Emilia-Romagna in 1585. It can be noted that the main course of the Po was northern before the "cutting of Porto Viro" of 1604.
The middle and east parts of Polesine in 1885. You can note that the main courses of the Adige and the Po are those of nowadays.
The Adige river as it enters the Polesine near Badia Polesine.