Great Rhone

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The southern two thirds of the Great Rhône with its mouth in the Mediterranean

The term Great Rhone ( French: Grand Rhône or Grand-Rhône ) describes the wider, eastern ( orographic left) of the two arms of the mouth of the Rhone into the Mediterranean. It begins at the Rhône fork (here the Little Rhone branches off ) about 3 kilometers north of Arles and flows about 50 kilometers south of Port-Saint-Louis-du-Rhône between Plage de Piémanson in the west and the former island They de Roustan in the east. Its western bank belongs to the Camargue , to the east it is largely bounded by the "island" Plan du Bourg formed by the Canal d'Arles à Fos and the Grand Rhône . Apart from the first two kilometers , which touch the Gard department , it runs continuously in the Bouches-du-Rhône department .

The Great Rhône carries around 90 percent of the total water volume of the Rhône, which averages 1700 cubic meters per second, but can increase to 13,000 cubic meters during floods (2003). Every year it transports 10 (before the construction of numerous dams on the tributaries even 20) million cubic meters of suspended matter, sand and rubble into the Mediterranean, which in the long term provides unimpeded access to the Gulf of Fos with the important industrial port in Fos-sur -Mer endangered. The considerable water and solids transport is also the reason why the river used to have silted up, unpredictable currents in the lower reaches and occasionally changed its course. Numerous former river arms that are gradually silting up date from this time.

History

Great Rhone near Arles

Already the Roman general Marius had 101 BC. To bypass the barely navigable estuary, build a canal (the so-called Fossae Marianae , still recognizable today in the course of the Bras Mort towards Port de Fos). Since the floods of 1587, the Great Rhône flowed west of its current route through the Bras de Fer branching off at Chamone (still visible on the map as Canal du Japon and the Vieux Rhône lagoon ) into the sea. Because this lower course, and thus the entire river as far as Arles, could not be reliably navigated for seagoing ships, Louis XIV had various engineers plan alternative approaches. During the flood in 1711 (according to another source in 1712), the Great Rhône surprisingly flowed mainly over the man-made, until then narrow Canal des Launes . This was then expanded, so that the current course of the river, which was navigable up to the mouth at that time, existed since 1725 and the Bras de Fer gradually silted up.

Since then, the Great Rhône has formed numerous flat, marshy islands ( they in Provencal ) in its estuary due to alluvial water, and over time they have pushed themselves further and further into the sea. Between 1712 and 1846 alone, it grew by 5640 meters. However, it was already foreseeable then that the increase of 23 meters per year at the end would decrease in the future because the estuary is less protected and the sea is deeper further away from the original mainland.

However, because the newly created part of the estuary could not be used by the emerging ships with a greater draft, the 4-kilometer-long eastern branch Canal Saint-Louis with the port of Port-Saint-Louis at its eastern end and subsequently the city were established between 1864 and 1871 Port-Saint-Louis-du-Rhône built.

The Great Rhône has been diked since the 18th century. Nevertheless, due to a lack of storage space, catastrophic flooding occurred in early December 2003 in the northern urban area of ​​Arles (80 million euros in damage).

Traffic routes

The Great Rhône can also be used by tourists as part of river cruises (from Arles). The only crossing by a road bridge is the flyover of the national road N 113 (European route E 80) near Arles. There is also the Bac de Barcarin ferry service near Salin-de-Giraud , which is also suitable for car transport . A railway bridge also runs parallel to this, connecting the salt pans Salins du Midi near Salin-de-Giraud with Port-Saint-Louis-du-Rhône and Fos-sur-Mer.

Individual evidence

  1. ↑ Inondations: Arles 13 mois après ( Memento of 15 February 2006 at the Internet Archive ). Contribution by Ingrid Estephan in Ambitions Sud International (le bimestriel économique des décideurs), N ° 45 - Janvier-Février 2005.

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