Somme River

From Wikipedia, the free encyclopedia

Somme
The Somme.
Origin	Picardie
Mouth	English Channel
Basin countries	France
Length	245 km
Source elevation	85 m
Avg. discharge	35 m³/s
Basin area	±6,000 km²

The Somme is a river in Picardy, northern France. The name Somme comes from a Celtic word meaning tranquility.

The river is 245 km long, from its source in the high ground of the former Forest of Arrouaise at Fonsommes near Saint-Quentin, to the Bay of the Somme, in the English Channel. It lies in the geological syncline which also forms The Solent. This gives it a fairly constant and gentle gradient.

1 Historical events
2 Départements and towns along the river
3 Main tributaries
4 Hydrology
- 4.1 Flow-rate data (external links)
5 Reference
6 External links

[edit] Historical events

The river is perhaps most famous as a result of the World War I Battle of the Somme (1916).
The Invasion Fleet of William the Conqueror assembled in the Bay of the Somme at Saint-Valery-sur-Somme, in 1066.
The river featured in the 1346 withdrawal of Edward III's army, which forded the river at the battle of Blanchetaque during the campaign which culminated in the Battle of Crécy.
Crossing the river also featured prominently in the campaign which led to the Battle of Agincourt some 501 years before the 1916 battle.
The great battles which finally stopped the German advance in the Spring Offensive of 1918 were fought around the valley of the Somme in places like Villers Bretonneux, which marked the beginning of the end of the war.

[edit] Départements and towns along the river

Aisne: Saint-Quentin
Somme : Ham, Péronne, Corbie, Amiens, Abbeville, Saint-Valery-sur-Somme, Le Crotoy

The estuary, on the English Channel is now much smaller than it was but is still extensive.

[edit] Main tributaries

Right bank

Omignon
Hallue
Nièvre
Scardon

Left bank

Avre
Selle
Saint-Landon
Airaine
Ambroise
Ancre

[edit] Hydrology

The river is characterized by a very gentle gradient and a steady flow. The valley is more or less steep-sided but its bottom is flat with fens and pools. These characteristics of steady flow and flooded valley bottom arise from the river's being fed by the ground water in the chalk basin in which it lies. At earlier, colder times, from the Günz to the Würm (Beestonian or Nebraskan to Devensian or Wisconsinian) the river has cut down into the Cretaceous geology to a level below the modern water table. The valley bottom has now therefore, filled with water which, in turn, has filled with fen. This picture, of the source of the Somme in 1986, shows it when the water table had fallen below the surface of the chalk in which the aquifer lies. Here, the flow of water had been sufficient to keep the fen from forming.

This satellite photograph shows the fenny valley crossing the chalk to the sea on the left. The sinuous length at the centre of the picture lies downstream from Péronne.

One of the fens, the Marais de l'Île is a nature reserve in the town of St.Quentin. The traditional market gardens of Amiens, the Hortillonages are on this sort of land but drained. Once exploited for peat cutting, the fen is now used for fishing and shooting.

The construction of the Canal de la Somme began in 1770 and reached completion in 1843. It is 156 km long, beginning at St.Simon and opening into the Bay of the Somme. From St.Simon to Froissy (near Bray sur Somme, south of Albert), the canal is alongside the river. Thence to the sea, the river is partly river and partly navigation. From Abbeville, it is diverted through the silted, former estuary, to Saint-Valéry-sur-Somme, where the maritime canal, once called the canal du Duc d'Angoulême enters the English Channel.

An example of the lakes formed in the fen of the valley bottom. They attract wildfowlers and anglers.

The St.Quentin Canal, famous for the 1918 battle, links the Somme to northern France and Belgium and southward to the Oise. The Canal du Nord also links the Somme to the Oise, at Noyon, thence to Paris.

In 2001, the Somme valley was affected by particularly high floods, which were in large part due to a rise in the water table of the surrounding land.