Editing Amiens (section)

===Hydrography: Somme and canal, Avre and Selle===
{{more citations needed|section|date=August 2024}}
[[File:LL 69 - AMIENS - Vue prise dans la vieille ville.JPG|thumb|left|150px|The Somme in the old town at the beginning of the 20th century]]
[[File:INCONNU - Vieil Amiens - Pont Becquet.JPG|thumb|right|The Becquet Bridge, at the start of the 20th century]]

The [[main stem]] of the [[River Somme]] passes through Amiens and is generally benign, except during exceptional floods that can last up to several weeks (such as in spring 2001). It is also, on its southeastern outskirts, close to [[Camon, Somme|Camon]] and [[Longueau]], the [[confluence]] with its main [[tributary]] on the left bank (to the south), and the [[Avre (Somme)|Avre]]. The [[Selle (Somme tributary)|Selle]] enters from the northwest of Amiens, with two arms (including the Haute Selle) passing behind the Unicorn Stadium, the exhibition park, the megacity and horse racing track, then passing the end of the ''Promenade de la Hotoie'' and the zoo of Amiens, and to the right of the water treatment plant, in front of the island Sainte-Aragone, opposite the cemetery of La Madeleine in Amiens.

The city developed in a natural narrowing of the river due to the advance of the rim of the Picard plateau in Saint-Pierre ([[Ford (crossing)|ford crossing]]).{{citation needed|date=March 2022}} The Amiens citadel is built on this limestone butte of the Picard plateau and ''Rue Saint-Pierre'' is a slightly inclined path to leave the city from the north. At this narrowing, a network of narrow canals led to the construction of bridges and buildings including [[Textile manufacturing|textile mills]] in the [[Middle Ages]].

The marshes of the old bed of the river Somme was used to dig peat. Farmers maintained rieux, canals and ditches by cleaning out the silt and used it to append to their vegetable garden plot. During the 20th century maintenance of the canals was stopped and gardens were gradually left to lie fallow or sold to private individuals who created pleasure gardens accessible by boat.<ref>{{Cite thesis |last=Albin |first=Claire |title=Preliminary study for the cleaning out of ditches and plans of water of the Hortillonnages of Amiens |date=October 2005 |degree=[[Diplôme d'études supérieures spécialisées|DESS]] |publisher=University of Tours |url=http://memoires.scd.univ-tours.fr/EPU_DA/LOCAL/2005-IMACOF-DESS-ALBIN-CLAIRE-ANGLAIS.pdf}}</ref>

The hydrographic network has always been an important city-operated asset. The river helped shape the identity of the landscape, urban and economic territory. It is around the Saint-Leu and Saint-Maurice neighborhoods that border the River Somme, as well as most of the administrative and civil area of the current city center which the city has developed since [[Ancient history|antiquity]].

The [[Canal de la Somme]] dates from the beginning of the 19th century and the bridge at the foot of the citadel was built after [[World War II]].