- Arno River
Infobox_River | river_name = Arno
caption = The Arno river
length = 241 km
elevation = 1,385 m
discharge = 110 m³/s (at the mouth)
watershed = 8,228 km²
The Arno is a
riverin the Tuscanyregion of Italy. It is the most important river of central Italy after the Tiber.
The river originates on
Mount Falteronain the Casentinoarea of the Apennines, and takes initially a southward curve. The river turns to the west near Arezzopassing through Florence, Empoliand Pisa, flowing into the Ligurian Seaat Marina di Pisa. With a length of 241 kilometers, it is the largest river in the region. Its main tributaries are: the Sieve (60 kilometers), Bisenzio (49 kilometers), Ombrone, Era, Elsa, Pesa and Pescia. The drainage basin amounts to more than 8,200 km² and drains the waters of the following sub-basins:
Casentino, in the province of Arezzo, formed by the upper course of the river until the confluence with the Maestro della Chiana channel.
*The Val di Chiana, a plain dried in the 18th century, which, until the 18th century, was a marshy area tributary of the Tiber.
Valdarno, a long valley bordered from East by the Pratomagnomassif and from West by the hills around Siena.
*The Sieve's basin, which flows in the Arno immediately before Florence.
*The middle Valdarno, with the plain including Florence,
Sesto Fiorentino, Pratoand Pistoia.
*The lower Valdarno, with the valley of important tributaries such as the Pesa, Elsa and Era and in which, after
Pontedera, the Arno flows into the Ligurian Sea. The river has a very variable discharge, ranging from minimum values such as 6 m³/s to more than 2,000. The mouth of the river was once near Pisa, but is now several kilometers westwards.
It crosses Florence, where it passes below the
Ponte Vecchioand the Santa Trinita bridge (built by Bartolomeo Ammannati, but inspired by Michelangelo). The river flooded this city regularly in historical times, the last occasion being the famous flood of 1966, with 4,500 m³/s after a rain of 437.2 mm in Badia Agnano and 190 millimetres in Florence, in only 24 hours.
The flow rate of the Arno is irregular. It is sometimes described as having a torrent-like behaviour, because it can easily go from almost dry to near-flood in a few days. At the point where the Arno leaves the Apennines, flow measurements can vary between 0.56 m³/s and 3,540 m³/s. New
dams built upstream of Florence have greatly alleviated the problem in recent years.
A flood on November 4, 1966 collapsed the embankment in Florence, killing at least 40 people and damaging or destroying millions of works of art and rare books. New conservation techniques were inspired by the disaster, but even 40 years later hundreds of works still await restoration. [cite journal | author = Alison McLean | year = 2006 | month = November | title = This Month in History | journal = Smithsonian | volume = 37 | issue = 8 | pages = 34 ]
* [http://www.adbarno.it/cont/testo.php?id=1 Basin Authority of the Arno] it icon
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