Editing Arno

{{other uses}}
{{Short description|Italian river in Tuscany}}
{{Infobox river
| name              = Arno 
| image             = FirenzeDec092023 01.jpg 
| map               = Arno (fleuve).png
| mapframe          = yes
| mapframe-zoom     = 7
| image_caption     = View of the Arno from the [[Piazzale Michelangelo]] 
| source1           = [[Monte Falterona]] 
| mouth             = [[Tyrrhenian Sea]] 
| mouth_location    = [[Marina di Pisa]] 
| mouth_coordinates = {{Coord|43.6802|10.2774|display=it|region:IT_type:river}}
| subdivision_type1 = Country
| subdivision_name1 = [[Italy]] 
| subdivision_type2 = Region
| subdivision_name2 = Tuscany
| length            = {{convert|241|km|mi|abbr=on}} 
| source1_elevation = {{convert|1385|m|ft|abbr=on}} 
| discharge1_avg    = {{convert|110|m3/s|cuft/s|abbr=on}} (at the mouth) 
| basin_size        = {{convert|8228|km2|mi2|abbr=on}}
| extra             = 
}}

The '''Arno''' is a [[river]] in the [[Tuscany]] region of [[Italy]]. It is the most important river of [[central Italy]] after the [[Tiber]].<ref>{{Cite web |title=Arno River - WorldAtlas |url=https://www.worldatlas.com/rivers/arno-river.html |access-date=January 14, 2024 |website=WorldAtlas|date=16 March 2023 }}</ref><ref>{{Cite web |title=The River Arno/ Tuscany's life force – PILOT GUIDES |url=https://www.pilotguides.com/articles/the-river-arno-tuscanys-life-force/ |access-date=January 14, 2024 |website=PILOT GUIDES|date=11 September 2023 }}</ref>

== Source and route ==
[[File:Arno watershed.png|thumb|Map of the Arno River watershed. ]]

The river originates on [[Monte Falterona]]<ref name="LIFE98 NAT/IT/005075">{{cite report |author=Parco Nazionale delle Foreste Casentinesi |date=1999-01-01 |title=Environmental restoration of the area of the river Arno offsprings |url=https://webgate.ec.europa.eu/life/publicWebsite/project/LIFE98-NAT-IT-005075/environmental-restoration-of-the-area-of-the-river-arno-offsprings# |publisher=European Climate, Infrastructure and Environment Executive Agency |access-date=2024-02-16 |quote="...on the southern slopes of Mount Falterona... the springs of the Arno River, described by the great poet Dante Alighieri, and the Etruscan archaeological site Lago degli Idoli are both located here.}}</ref> in the [[Casentino]] area of the [[Apennine Mountains|Apennines]], and initially takes a southward curve. The river turns to the west near [[Arezzo]] passing through [[Florence]], [[Empoli]] and [[Pisa]],<ref name="Encyclopedia Britannica 1998 z588">{{cite web | title=Arno River | website=Encyclopedia Britannica | date=July 20, 1998 | url=https://www.britannica.com/place/Arno-River | access-date=February 16, 2024}}</ref> flowing into the [[Ligurian Sea]]<ref name="Magazine Solly 2018 z520">{{cite web | last1=Magazine | first1=Smithsonian | last2=Solly | first2=Meilan | title=Like a Reverse Atlantis, This Legendary Harbor Ended When Its Sea Route Dried Up | website=Smithsonian Magazine | date=August 24, 2018 | url=https://www.smithsonianmag.com/smart-news/rising-sea-levels-changing-environment-doomed-legendary-pisan-harbor-180970132/ | access-date=February 16, 2024}}</ref><ref name="Encyclopedia Britannica 1965 b099">{{cite web | title=Interesting facts about the Arno River | website=Encyclopedia Britannica | date=March 12, 1965 | url=https://www.britannica.com/summary/Arno-River | access-date=February 16, 2024}}</ref> at [[Marina di Pisa]].<ref name="La Nazione 2023 g129">{{cite web | title=Marina di Pisa, la mareggiata si porta via lo storico retone di Bocca d'Arno | website=La Nazione | date=November 3, 2023 | url=https://www.lanazione.it/pisa/cronaca/retone-boccadarno-mareggiata-sb48sb4d | language=it | access-date=February 16, 2024}}</ref><ref name="PisaToday 2023 c967">{{cite web | title=Mareggiata Marina di Pisa | website=PisaToday | date=November 3, 2023 | url=https://www.pisatoday.it/cronaca/allagamenti-marina-pisa-mareggiata-3-novembre-2023.html | language=it | access-date=February 16, 2024}}</ref>

With a length of {{convert|241|km}}, it is the largest river in the region. It has many tributaries: [[Sieve (river)|Sieve]] at {{convert|60|km|mi}} long, [[Bisenzio (river)|Bisenzio]] at {{convert|49|km}}, [[Ombrone Pistoiese]] at {{convert|47|km}}, and the [[Era (river)|Era]], [[Elsa (river)|Elsa]], [[Pesa (river)|Pesa]], and [[Pescia (river)|Pescia]]. The [[drainage basin]] amounts to more than {{convert|8200|sqkm}} and drains the waters of the following subbasins:

*The [[Casentino]], in the [[province of Arezzo]], formed by the upper course of the river until its confluence with the Maestro della Chiana channel.
*The [[Valdichiana|Val di Chiana]], a plain drained in the 18th century, which until then had been a marshy area tributary of the Tiber.
*The upper [[Valdarno]], a long valley bordered on the east by the [[Pratomagno]] massif and on the west by the hills around [[Siena]].
*The Sieve's basin, which flows into the Arno immediately before Florence.
*The middle Valdarno, with the plain including Florence, [[Sesto Fiorentino]], [[Prato]], and [[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 about {{convert|6|m3/s|cuft/s}} to more than {{convert|2000|m3/s|cuft/s}}. The mouth of the river was once near [[Pisa]] but is now several kilometres westwards.
[[File:Ponte Vecchio.jpg|thumb|250px|left|"Ponte Vecchio" (The old bridge) over the Arno in Florence]]
[[File:View From the Ponte Vecchio of the River Arno.jpg|thumb|250px|left|View of the Arno from the [[Ponte Vecchio]]]]
It crosses [[Florence]], where it passes below the [[Ponte Vecchio]] and the [[Ponte Santa Trinita|Santa Trinita bridge]] (built by [[Bartolomeo Ammannati]] but inspired by [[Michelangelo]]). The river [[flood]]ed this city regularly in historical times, most recently in [[1966 flood of the Arno|1966]], with {{convert|4500|m3/s|cuft/s}} after rainfall of {{convert|437.2|mm}} in Badia Agnano and {{convert|190|mm}} in Florence, in only 24 hours.{{Citation needed|date=January 2024}}

Before Pisa, the Arno is crossed by the Imperial Canal at La Botte. This water channel passes under the Arno through a tunnel, and serves to drain the former area of the [[Lago di Bientina]], which was once the largest lake in [[Tuscany]] before its reclamation. 

The flow rate of the Arno is irregular. It is sometimes described as having a torrentlike 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 {{convert|0.56|and|4100 |m3/s|cuft/s}}. New [[dam]]s built upstream of Florence have greatly alleviated the problem in recent years.{{Citation needed|date=February 2023}}

[[File:FirenzeArno1547.jpg|thumb|right|[[High water mark]]s of Arno river floods on August 13, 1547 (left) and November 3, 1844 (metal plate on the right). Photographed in Via delle Casine.]] 

The [[1966 flood of the Arno|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 decades later hundreds of works still await restoration.<ref>{{cite journal | author = Alison McLean |date=November 2006 | title = This Month in History | journal = Smithsonian | volume = 37 | issue = 8 | pages = 34 }}</ref>

== Etymology ==
From Latin ''Arnus'' (Pliny, ''Natural History'' 3.50). The philologist [[Hans Krahe]] related this toponym on a [[Old European hydronymy|paleo-European]] basis ''*Ar-n-'', derived from the [[Proto-Indo-European]] root *''er-'', "flow, move".<ref>Edelmiro Bascuas, ''Hidronimia y léxico de origen paleoeuropeo en Galicia'' (page 41)</ref>. The [[hydronym]] is closely akin to another nearby hydronym, for the [[Reno (river)]].

== Ecology ==
The Arno river has been strongly affected by non-native species: over 90% of fish species and 70% of macroinvertebrate species in the area around Florence are alien species.<ref name=":0">{{Cite journal|last1=Haubrock|first1=Phillip J.|last2=Pilotto|first2=Francesca|last3=Innocenti|first3=Gianna|last4=Cianfanelli|first4=Simone|last5=Haase|first5=Peter|date=2021|title=Two centuries for an almost complete community turnover from native to non-native species in a riverine ecosystem|journal=Global Change Biology|language=en|volume=27|issue=3|pages=606–623|doi=10.1111/gcb.15442|pmid=33159701 |bibcode=2021GCBio..27..606H |s2cid=226274730 |issn=1365-2486|doi-access=free}}</ref> These include the [[Wels catfish|European catfish]],<ref name=":1">{{Cite journal|last1=Haubrock|first1=Phillip Joschka|last2=Azzini|first2=Martina|last3=Balzani|first3=Paride|last4=Inghilesi|first4=Alberto Francesco|last5=Tricarico|first5=Elena|date=2020|title=When alien catfish meet—Resource overlap between the North American Ictalurus punctatus and immature European Silurus glanis in the Arno River (Italy)|journal=Ecology of Freshwater Fish|language=en|volume=29|issue=1|pages=4–17|doi=10.1111/eff.12481|s2cid=149848379 |issn=1600-0633|doi-access=free|bibcode=2020EcoFF..29....4H |hdl=2158/1262515|hdl-access=free}}</ref> [[channel catfish]],<ref name=":1" /> [[Crucian carp]],<ref name=":0" /> [[common bleak]],<ref name=":2">{{Cite journal|last1=Balzani|first1=Paride|last2=Gozlan|first2=Rodolphe E.|last3=Haubrock|first3=Phillip J.|date=2020|title=Overlapping niches between two co-occurring invasive fish: the topmouth gudgeon Pseudorasbora parva and the common bleak Alburnus alburnus|url=https://onlinelibrary.wiley.com/doi/abs/10.1111/jfb.14499|journal=Journal of Fish Biology|language=en|volume=97|issue=5|pages=1385–1392|doi=10.1111/jfb.14499|pmid=33460088 |bibcode=2020JFBio..97.1385B |s2cid=224936178 |issn=1095-8649|url-access=subscription}}</ref> [[Stone moroko|topmouth gudgeon]],<ref name=":2" /> [[New Zealand mud snail]],<ref name=":0" /> and [[Dikerogammarus villosus|killer shrimp]].<ref name=":0" /> The [[Rhithropanopeus harrisii|mud crab]] has been found in the river near Pisa.<ref>{{Cite journal|last1=Langeneck|first1=J.|last2=Barbieri|first2=M.|last3=Maltagliati|first3=F.|last4=Castelli|first4=A.|date=2015-11-18|title=The low basin of the Arno River (Tuscany, Italy) as alien species hotspot: first data about Rhithropanopeus harrisii (Crustacea, Panopeidae)|url=http://siba-ese.unisalento.it/index.php/twb/article/view/15385|journal=Transitional Waters Bulletin|volume=9|issue=1|pages=1–10|doi=10.1285/i1825229Xv9n1p1|issn=1825-229X}}</ref>

== Uses and human impacts ==
Water from the Arno drainage basin is used for drinking water, irrigation, and firefighting.<ref name=":3">{{Cite journal|last1=Pacetti|first1=T.|last2=Castelli|first2=G.|last3=Bresci|first3=E.|last4=Caporali|first4=E.|date=2020-11-01|title=Water Values: Participatory Water Ecosystem Services Assessment in the Arno River Basin, Italy|journal=Water Resources Management|language=en|volume=34|issue=14|pages=4527–4544|doi=10.1007/s11269-020-02684-4|s2cid=222279681 |issn=1573-1650|doi-access=free|bibcode=2020WatRM..34.4527P |hdl=2158/1209763|hdl-access=free}}</ref> Citizens in the central part of the drainage basin also identified flood control, support for biodiversity, fisheries, and cultural value as other services that the river provides.<ref name=":3" /> There is the risk that flooding will jeopardize these [[ecosystem service]]s, as 9% of wastewater treatment plants, 10% of landfills or other waste sites, and 4.5% of contaminated sites are at high risk of flooding, which would produce hotspots of pollution.<ref>{{Cite journal|last1=Arrighi|first1=Chiara|last2=Masi|first2=Matteo|last3=Iannelli|first3=Renato|date=2018-02-01|title=Flood risk assessment of environmental pollution hotspots|url=https://www.sciencedirect.com/science/article/pii/S1364815217305169|journal=Environmental Modelling & Software|language=en|volume=100|pages=1–10|doi=10.1016/j.envsoft.2017.11.014|bibcode=2018EnvMS.100....1A |hdl=11568/877149 |issn=1364-8152|hdl-access=free}}</ref>

==Gallery==
<gallery widths="200px" heights="160px">
File:Arno_river.jpg|The Arno in Florence
File:Arno River in Pisa.honeydew.jpg|The Arno in [[Pisa]], near the Ponte della Fortezza (Fortress Bridge)
File:Firenze.Arno.jpg|Banks of the Arno, seen from the [[Ponte Vecchio]] (Old Bridge), [[Florence]]
File:Arno_Mouth_Italy_aerial_view.jpg|Mouth of the Arno in [[Marina di Pisa]]
File:Florence Arno 180.jpg|The Arno in [[Florence]], 180 degree view: the [[Uffizi]] Gallery is straight across and the [[Ponte Vecchio]] is to the left
File:Florence at night.jpg|The Arno in [[Florence]] at night
File:Ponte amerigo vespucci.JPG|The [[Ponte Amerigo Vespucci]] (Amerigo Vespucci Bridge)
</gallery>

==References==
{{reflist}}

==External links==
{{Commons category}}
*[http://www.adbarno.it/cont/testo.php?id=1 Basin Authority of the Arno] {{in lang|it}}

{{Authority control}}

[[Category:Rivers of Italy]]
[[Category:Rivers of Tuscany]]
[[Category:Geography of Florence]]
[[Category:Geography of Pisa]]
[[Category:Rivers of the Province of Arezzo]]
[[Category:Rivers of the Metropolitan City of Florence]]
[[Category:Rivers of the Province of Pisa]]
[[Category:Rivers of the Province of Prato]]
[[Category:Rivers of the Apennines]]
[[Category:Drainage basins of the Tyrrhenian Sea]]