Po-Venetian Plain

a plain in northern Italy bounded by the Alps, Apennines, and Adriatic Sea and located mainly within the Po River basin. It is about 500 km long, with widths to 200 km (in the east). The plain was formed when a gulf situated in a tectonic trough was filled by sea, river, and glaciofluvial deposits that are now more than 8 km thick. The surface, which is mostly flat, descends gradually from 300 to 400 m in the west to sea level in the east. In the center of the plain there are low clayey plains with fertile alluvial soils; along the edges are high plains of sand and pebble. Some regions in the lower reaches of the Po are below sea level.

The climate ranges from subtropical to moderate. The average January temperature ranges from 0° to 4°C, while the average July temperature ranges from 22° to 24°C. Precipitation totals 600–1,000 mm annually, with the greatest amounts falling in the spring, early summer, and autumn; a snow cover does not form. There is a dense network of rivers of the Po, Adige, and Brenta river basins, with high water occurring in spring and autumn. The rivers that empty into the Adriatic Sea are meandering. There are fairly frequent floods, with the most recent major floods occurring in 1951, 1957, and 1966. In an attempt to prevent flooding, many rivers have been diked. There is a dense network of irrigation, drainage, and shipping canals.

The plain was once covered by broad-leaved forests that contained oak, chestnut, linden, beech, and elm trees and by willow forests, but nearly all the trees have been felled. The vegetation of the reed swamps and peat bogs is still abundant, especially in the delta regions. The plain is the bread basket of Italy. Its main agricultural crops are wheat, corn, and rice, and there are vineyards and orchards. Milan, Turin, Venice, and Bologna are the major cities.