Saône Basin

The Saône ( , ; frp, Sona; lat, Arar) is a river in eastern France. It is a right tributary of the Rhône, rising at Vioménil in the Vosges department and joining the Rhône in Lyon, at the southern end of the Presqu'île.

The name derives from that of the Gallic river goddess Souconna, which has also been connected with a local Celtic tribe, the Sequanes. Monastic copyists progressively transformed ''Souconna'' to ''Saoconna'', which ultimately gave rise to . The other recorded ancient names for the river were and .

Geography

The Saône rises at Vioménil at the foot of the cliff of the Faucilles in the Vosges at an elevation of , and flows into the Rhône at Lyon at an elevation of . Its length is . Its largest tributary is the Doubs than the Doubs, at ''vs.'' .

At the Saône has the largest watershed of any French river that does not flow directly into the sea, covering approximately 1/18 of metropolitan France.

In pre-Roman times the river's name was "Arar", a doubling of the Indo-European root ''ar'' (water). According to Caesar's Gallic Wars this doubling reflected the idea that it was difficult to identify the direction of the river due to its slow rate of flow. Its current name came from a sacred spring, ''Sauc-Onna'', located at Chalon, which was used by Roman legionaries to refer to the entire river.

Departments and cities traversed by the Saône

* Vosges: Darney, Monthureux-sur-Saône, Châtillon-sur-Saône
* Haute-Saône, Corre, Jussey, Port-sur-Saône, Scey-sur-Saône, Gray
* Côte-d'Or, Saint-Jean-de-Losne, Seurre
* Saône-et-Loire: Verdun-sur-le-Doubs, Tournus, Mâcon, Crêches-sur-Saône
* Rhône: Belleville-sur-Saône, Villefranche-sur-Saône, Anse, Neuville-sur-Saône, Fontaines-sur-Saône, Caluire-et-Cuire, Lyon
* Ain: Thoissey, Jassans-Riottier,

Main tributaries of the Saône

R indicates a right tributary, L indicates a left tributary.

Navigation

The Saône is navigable from its confluence with the Coney at Corre in the north of the ''département'' Haute-Saône (itself a navigable river) at La Mulatière, in Lyon. The navigable stretch is long, of which has been redeveloped to European high-capacity dimensions from Saint-Symphorien-sur-Saône to Lyon. It has 5 locks. The 161 km long part upstream from Saint-Symphorien-sur-Saône to Corre, also named ''Petite Saône'', is navigable for Freycinet gauge ships and has 19 locks.

The Saône is linked with the Loire by the Canal du Centre, with the Yonne by the Canal de Bourgogne, with the Marne by the Canal entre Champagne et Bourgogne (previously the Canal de la Marne à la Saône), with the Meuse by the Canal de l'Est, whose southern branch has been renamed the Canal des Vosges, and with the Rhine by the Canal du Rhône au Rhin. All the canals are Freycinet gauge.

Also navigable are the small Canal de Pont-de-Vaux (3 km), the Seille, navigable in a stretch up to Louhans, and the lower part of the Doubs. None of these three connect the Saône to any other waterway.

Hydrology

The lesser Saône (Petite Saône)

The lesser Saône has a tendency to flood (sometimes influenced by snow), with a very strong oceanic effect. The soils are not susceptible to much infiltration, so that they saturate quickly which contributes to surface runoff. The flow rate grows very quickly, and after receiving the waters of the Lanterne, the Saône already becomes a powerful river.

The mean annual flow rate, or discharge, of the Saône has been measured over 50 years (as of 2013) at the Ray-sur-Saône hydrological station, situated about after the Lanterne confluence between Port-sur-Saône and Gray.
The figure is for a watershed area of (the upper basin of the lesser Saône), and has an annual maximum of and a minimum of .

The river exhibits seasonal variations in flow rate, with winter floods from from December to March inclusive, and summer reductions in July/August/September falling to a monthly average of in August.

The runoff curve number in the upper basin of the lesser Saône is annually, ''cf.'' for the Lanterne, an elevated figure resulting from the very high rainfall in the Vosgian part of its watershed. The specific flow rate rises to 16.0 litres per second per square kilometre of watershed.

The maximum instantaneous recorded flow rate was on December 19, 1982.

The greater Saône (Grande Saône)

The greater Saône is formed by the confluence of the Doubs and the lesser Saône at Verdun-sur-le-Doubs. The Doubs brings a mean annual flow rate of , and the lesser Saône, .

The greater Saône has only modest tributaries which have little effect on floods or other hydrological properties. It flows in a vast plain approximately wide as far as Lyon in the basin of the former Bressan lake. The slope is very gradual, and without hydraulic projects up to the north of Chalon aimed at guaranteeing a deep navigation channel, overflows would be more frequent.

At the Couzon-au-Mont-d'Or hydrological station, where the river enters the Lyon area, measurements taken between 1969 and 1986 revealed a mean annual flow rate of , with a 100-year flood flow rate of The runoff curve number from the river's entire watershed is , and the specific flow rate rises to 15.8 litres per second per square km of watershed.

Average flow rate

Overall, the average flow rate in Lyon is , with a minimum of , in August, and a maximum of , in February.

Historic floods

When the Saône floods, the impact varies considerably over the course of the river. A large flood with a strong flow rate upstream can be largely attenuated in the Bressan plain so as to have only moderate impact at Mâcon, particularly if it carries a limited volume of water. By contrast, a medium-sized flood of the lesser Saône can turn into a significant flood downstream, if the Doubs brings in a similar contribution at about the same time.

Historic floods include:
* The Lyon flood of 580
* The floods of 1602 during the autumn equinoxFloods of the Rhône and all its tributaries, Volume 4
/ref> and of 1711
* The flood of November 1840, with an estimated flow rate of almost , destroyed numerous habitations along the river valley. Many plaques marking this serious event are still visible in the villages affected. The high water measured at flood scales reached at Mâcon and at Chalon, or about respectively above normal levels).
* The flood of May 1856
* The largest floods in the last 50 years as of 2006: January 1955, March 1970, December 1981 and 1982, May 1983, March 2001 and 2006.

The reference flood in town planning is the 100-year flood. This reference was in the course of being modified as maps linked to modelling the 1840 flood in modern town planning conditions were distributed to local mayors in December 2008, and as new prevention plans were ordered for 2012.

File:SAONE1840.jpg, A plaque commemorating the flood of 1840 at Quincieux
File:Saône - échelle des inondations à Ecuelles.JPG, Historic floods since 1950 Écuelles, north Saône-et-Loire
File:Niveau crue Saône Belleville.jpg, Indicators of the level of historic floods of the Saône on the Church of Notre-Dame de Belleville

See also

* List of rivers in France
* The Rhône
* The Doubs is also a French commune in the département of Doubs
* Chizerots

References

External links

River Saône (Petite Saône)
with maps and information on places, ports and moorings on the river from Corre to Saint-Jean-de-Losne, by the author of ''Inland Waterways of France'', Imray

River Saône (Grande Saône)
with maps and information on places, ports and moorings on the river from Saint-Jean-de-Losne to Lyon, by the author of ''Inland Waterways of France'', Imray

Navigation details for 80 French rivers and canals
(French waterways website section)

Waterways in France
*
Saone.org : French river cruising

The Saône
on OpenStreetMap
*
Saone.org
Navigation and information about the Saône
*

The Saône
*
Navigable routes in France
on the website of Voies Navigables de France

{{DEFAULTSORT:Saone

Rivers of Ain
Rivers of Côte-d'Or
Rivers of France
Rivers of Bourgogne-Franche-Comté
Rivers of Haute-Saône
Rivers of Grand Est
Rivers of Rhône (department)
Rivers of Auvergne-Rhône-Alpes
Rivers of Saône-et-Loire
Rivers of Vosges (department)