The Tanaro (; ; ; ) is a long

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

in northwestern

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

. The river begins in the

Ligurian Alps The Ligurian Alps are a mountain range in northwestern Italy. A small part is located in France. They form the south-western extremity of the Alps, separated from the Apennine Mountains, Apennines by the Colle di Cadibona. The Col de Tende and the ...

, near the border with

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

, and is the most significant right-side tributary to the Po in terms of length, size of

drainage basin A drainage basin is an area of land in which all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...

(partly Alpine, partly Apennine), and discharge.

Geography

Sources

The Tanaro rises at the border between

Piedmont Piedmont ( ; ; ) is one of the 20 regions of Italy, located in the northwest Italy, Northwest of the country. It borders the Liguria region to the south, the Lombardy and Emilia-Romagna regions to the east, and the Aosta Valley region to the ...

and

Liguria Liguria (; ; , ) is a Regions of Italy, region of north-western Italy; its Capital city, capital is Genoa. Its territory is crossed by the Alps and the Apennine Mountains, Apennines Mountain chain, mountain range and is roughly coextensive with ...

at the confluence of two smaller streams: the Tanarello and the Negrone. The main source of the Tanarello is on the slopes of Monte Saccarello above Monesi, a village belonging to the commune of Triora. This mountain straddles the French

département In the administrative divisions of France, the department (, ) is one of the three levels of government under the national level (" territorial collectivities"), between the administrative regions and the communes. There are a total of 101 ...

Alpes-Maritimes Alpes-Maritimes (; ; ; ) is a Departments of France, department of France located in the country's southeast corner, on the France–Italy border, Italian border and Mediterranean Sea, Mediterranean coast. Part of the Provence-Alpes-Côte d'A ...

, the Piedmontese

province of Cuneo The province of Cuneo (; ) is a province in the Piedmont region of Italy. To the west, it borders the French region of Provence-Alpes-Côte d'Azur ( departments of Alpes-Maritimes, Alpes-de-Haute-Provence and Hautes-Alpes), to the north the ...

and the Ligurian

province of Imperia The province of Imperia (; ; ) is a mountainous and hilly Provinces of Italy, province in the Liguria region of Italy, situated between France to the north and the west, and the Ligurian Sea, an arm of the Mediterranean Sea to the south. Its capi ...

and marks the juncture of the watersheds between three

s: Tanaro itself; Roya (), which rises in France but enters the sea at

Ventimiglia Ventimiglia (; , ; ; ) is a resort town in the province of Imperia, Liguria, northern Italy. It is located west of Genoa, and from the French-Italian border, on the Gulf of Genoa, having a small harbour at the mouth of the Roia river, w ...

; and

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

, which flows into the

Ligurian Sea The Ligurian Sea is an arm of the Mediterranean Sea. It lies between the Italian Riviera ( Liguria) and the island of Corsica. The sea is thought to have been named after the ancient Ligures people. Geography The sea borders Italy as far as ...

at Taggia. The sources of the Negrone are not far from Punta Marguareis and very close to the French border.

Course

The Tanaro flows through the towns of

Ormea Ormea is a ''comune'' (municipality) in the Province of Cuneo in the Italian region Piedmont, located about south of Turin and about southeast of Cuneo. Ormea borders the following municipalities: Alto The musical term alto, meaning "high" ...

, Garessio, Ceva,

Alba ''Alba'' ( , ) is the Scottish Gaelic name for Scotland. It is also, in English-language historiography, used to refer to the polity of Picts and Scots united in the ninth century as the Kingdom of Alba, until it developed into the Kingd ...

Asti Asti ( , ; ; ) is a ''comune'' (municipality) of 74,348 inhabitants (1–1–2021) located in the Italy, Italian region of Piedmont, about east of Turin, in the plain of the Tanaro, Tanaro River. It is the capital of the province of Asti and ...

, and

Alessandria Alessandria (; ) is a city and commune in Piedmont, Italy, and the capital of the Province of Alessandria. It is also the largest municipality of the region. The city is sited on the alluvial plain between the Tanaro and the Bormida rivers, ...

before flowing into

Po river The Po ( , ) is the longest river in Italy. It flows eastward across northern Italy, starting from the Cottian Alps. The river's length is , or if the Maira (river), Maira, a right bank tributary, is included. The headwaters of the Po are forme ...

near Bassignana in the

Province of Alessandria The province of Alessandria (; ; in Piedmontese of Alessandria: ''provinsa ëd Lissändria'') is an Italian Provinces of Italy, province, with a population of some 425,000, which forms the southeastern part of the region of Piedmont. The prov ...

. At its confluence with the Po, the Tanaro is about 50 km longer than the upper Po, a case similar to the famous

Missouri Missouri (''see #Etymology and pronunciation, pronunciation'') is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it border ...

tributary being longer than

Mississippi Mississippi ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South regions of the United States. It borders Tennessee to the north, Alabama to the east, the Gulf of Mexico to the south, Louisiana to the s ...

in the United States.

Tributaries

The main tributaries to the Tanaro are the Stura di Demonte, the Pesio, the Ellero and the Borbore from the left and the Bormida and the Belbo from the right.

Regime

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 of snow fields or

glaciers A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

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 Apennine

stream A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a strea ...

, with a maximum discharge that can reach , in spring and autumn and a very low rate of flow in the summer.

Flood events

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.

History

The left bank of the Tanaro River near Asti is the scene of the

Battle of Pollentia The Battle of Pollentia was fought on 6 April 402 between the Romans under Stilicho and the Visigoths under Alaric I, during the first Gothic invasion of Italy (401–403). The Romans were victorious, and forced Alaric to retreat, though he r ...

on April 6, 402.

References

* The article draws on material from related articles in the

Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, a Romance ethnic group related to or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance languag ...

, French and German Wikipedias, as retrieved 14 June 2006 *
SUL MONTE SACCARELLO :: Una camminata alla scoperta delle sorgenti del Tanaro
* * Luino F. (1999): “The flood and landslide event of November 4–6, 1994 in Piedmont Region (North-West Italy): causes and related effects in Tanaro Valley”. XXII General Assembly dell’European Geophysical Society, Vienna (Austria). 21–25 April 1997. Ed. Elsevier Science Ltd, Vol. 24, N. 2, p. 123-129.