The Santerno is a river in

Romagna Romagna () is an Italian historical region that approximately corresponds to the south-eastern portion of present-day Emilia-Romagna, in northern Italy. Etymology The name ''Romagna'' originates from the Latin name ''Romania'', which originally ...

northern Italy Northern Italy (, , ) is a geographical and cultural region in the northern part of Italy. The Italian National Institute of Statistics defines the region as encompassing the four Northwest Italy, northwestern Regions of Italy, regions of Piedmo ...

. It is a major tributary of the river

Reno Reno ( ) is a city in the northwest section of the U.S. state of Nevada, along the Nevada–California border. It is the county seat and most populous city of Washoe County, Nevada, Washoe County. Sitting in the High Eastern Sierra foothills, ...

. In

Roman Roman or Romans most often refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of Roman civilization *Epistle to the Romans, shortened to Romans, a letter w ...

times, it was known as the ''Vatrenus'' (small ''Renus''), although, in the

Tabula Peutingeriana ' (Latin Language, Latin for 'The Peutinger Map'), also known as Peutinger's Tabula, Peutinger tablesJames Strong (theologian) , James Strong and John McClintock (theologian) , John McClintock (1880)"Eleutheropolis" In: ''The Cyclopedia of Bibli ...

, it was already identified as the ''Santernus''. It rises near the

Futa Pass The Futa Pass or La Futa Pass () is a Pass (geography), pass in the Tuscan-Emilian Apennines, at an elevation of . It is located in the ''comune'' of Firenzuola, in the Metropolitan City of Florence. It separates the valleys of Mugello (region), M ...

, at of elevation, in the Apennine ridges facing the plateau of

Firenzuola Firenzuola is a ''comune'' (municipality) in the Metropolitan City of Florence, in the Italian region Tuscany, located about northeast of Florence. Firenzuola borders the following municipalities: Barberino di Mugello, Borgo San Lorenzo, Cast ...

in the

Metropolitan City of Florence The Metropolitan City of Florence () is an administrative division called metropolitan city in the Tuscany region of Italy. Its capital is the city of Florence. It replaced the province of Florence. It was first created by the reform of local a ...

. Beyond Firenzuola, it flows northeast through the

province of Bologna The province of Bologna () was a province in the Emilia-Romagna region of Italy. Its provincial capital was the city of Bologna. The province of Bologna covered an area of and had a total population of 1,004,323 inhabitants as of 31 December 2014 ...

near Castel del Rio, where it is crossed by a famous medieval bridge, the ''Ponte degli Alidosi''. It then flows past Fontanelice, Borgo Tossignano,

Casalfiumanese Casalfiumanese () is a ''comune'' (municipality) in the Metropolitan City of Bologna in the Italian region Emilia-Romagna, located about southeast of Bologna. Casalfiumanese borders the following municipalities: Borgo Tossignano, Castel del Rio ...

, and, once in the Pianura Padana (the

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 ...

's valley),

Imola Imola (; or ) is a city and ''comune'' in the Metropolitan City of Bologna, located on the river Santerno, in the Emilia-Romagna region of northern Italy. The city is traditionally considered the western entrance to the historical region Romagna ...

. The river forms the border between the province of Bologna and the

province of Ravenna The province of Ravenna (; ) is a province in the Emilia-Romagna region of Italy. Its capital is the city of Ravenna. As of 2015, it has a population of 391,997 inhabitants over an area of , giving it a population density of 210.81 inhabitants pe ...

for a distance before entering the province of Ravenna. It then empties into the Reno near Argenta. It is probable that, in ancient times, the river flowed eastward from

Bagnacavallo Bagnacavallo () is a town and ''comune'' in the province of Ravenna, Emilia-Romagna, Italy. The Renaissance painter Bartolomeo Ramenghi bore the nickname of his native city. Main sights *''Castellaccio'' (15th century) * Giardino dei Semplici ...

, as confirmed be the existence of a ''

frazione A ''frazione'' (: ''frazioni'') is a type of subdivision of a ''comune'' ('municipality') in Italy, often a small village or hamlet outside the main town. Most ''frazioni'' were created during the Fascist era (1922–1943) as a way to consolidat ...

'' of

Ravenna Ravenna ( ; , also ; ) is the capital city of the Province of Ravenna, in the Emilia-Romagna region of Northern Italy. It was the capital city of the Western Roman Empire during the 5th century until its Fall of Rome, collapse in 476, after which ...

called Santerno. In those days, after Imola, the river divided into two branches, one moving northeast toward Ravenna, the other continuing northward to join the Po. The Ravenna branch disappeared, most likely in the eighth century. Once the late course of the river was modified, and protective measures were taken in the 1880s, the Santerno was famous for its serious floods. Fourteen were recorded between 1679 and 1778.

Footnotes

Rivers of the Metropolitan City of Florence Rivers of the Metropolitan City of Bologna Rivers of the Province of Ravenna Rivers of the Apennines Rivers of Italy {{Italy-river-stub