| Tanaro | |
|---|---|
 NearAlessandria | |
 | |
| Native name | Tane (Piedmontese) |
| Location | |
| Country | Italy |
| Physical characteristics | |
| Source | |
| • location | Ligurian Alps, on the slopes ofMonte Saccarello |
| Mouth | |
• location | Po nearBassignana (AL) |
• coordinates | 45°00′20″N8°46′10″E / 45.00556°N 8.76944°E /45.00556; 8.76944 |
| Length | 276 km (171 mi) |
| Basin size | 8,234 km2 (3,179 sq mi) |
| Discharge | |
| • average | 123 m3/s (4,300 cu ft/s) |
| Basin features | |
| Progression | Po→Adriatic Sea |
| Tributaries | |
| • left | Ellero,Stura di Demonte,Borbore,Versa |
| • right | Belbo,Bormida |
TheTanaro (Italian pronunciation:[ˈtaːnaro];Piedmontese:Tane[ˈtɑne];Ligurian:Tànau[ˈtana(ɹ)u];Latin:Tanarus) is a 276-kilometre (171 mi) longriver in northwesternItaly. The river begins in theLigurian Alps, near the border withFrance, and is the most significant right-side tributary to thePo in terms of length, size ofdrainage basin (partlyAlpine, partlyApennine), anddischarge.
The Tanaro rises at the border betweenPiedmont andLiguria at the confluence of two smaller streams: theTanarello and theNegrone.
The main source of the Tanarello is on the slopes ofMonte Saccarello above Monesi, a village belonging to the commune ofTriora. This mountain straddles theFrenchdépartement ofAlpes-Maritimes, the Piedmonteseprovince of Cuneo and the Ligurianprovince of Imperia and marks the juncture of thewatersheds between threedrainage basins: Tanaro itself;Roya (Italian:Roia), which rises in France but enters the sea atVentimiglia; andArgentina, which flows into theLigurian Sea atTaggia.
The sources of the Negrone are not far fromPunta Marguareis and very close to the French border.
The Tanaro flows through the towns ofOrmea, Garessio,Ceva,Alba,Asti, andAlessandria before flowing intoPo river nearBassignana in theProvince of Alessandria. At its confluence with the Po, the Tanaro is about 50 km longer than the upper Po,[1] a case similar to the famousMissouri tributary being longer thanMississippi in the United States.
The main tributaries to the Tanaro are theStura di Demonte, thePesio, theEllero and theBorbore from the left and theBormida and theBelbo from the right.
The flow is subject to a great seasonal variation. Although the river has an Alpine origin, which is unique among the Po’s right-side tributaries, the Ligurian Alps are of an insufficient elevation and too close to the sea to allow for the formation ofsnow fields orglaciers large enough to provide a steady source of water during the summer. Furthermore, the Alpine zone forms only a part of the basin drained by the Tanaro. The seasonal regime of the river is therefore more typical of an Apenninestream, with a maximum discharge that can reach 1,700 cubic metres per second (60,000 cu ft/s), in spring and autumn and a very low rate of flow in the summer.
The river is highly prone to flooding. During the two-hundred-year period between 1801 and 2001, sections of the Tanaro basin were affected by floods on 136 occasions. The most devastating floods were in November 1994, November 2016, October 2020, when the whole valley was affected by severe flooding.
The left bank of the Tanaro River near Asti is the scene of theBattle of Pollentia on April 6, 402.
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