Aller (Germany)

The Aller (pronounced [ˈalɐ]) is a 215-kilometre-long (134 mi) river in the states of Saxony-Anhalt and Lower Saxony in Germany. It is a right-hand, and hence eastern, tributary of the Weser and is also its largest tributary. Its last 117 kilometres (73 mi) form the Lower Aller federal waterway (Bundeswasserstraße). The Aller was extensively straightened, widened and, in places, dyked during the 1960s to provide flood control of the river. In a 20-kilometre-long (12 mi) section near Gifhorn, the river meanders in its natural river bed.

The river's name, which was recorded in 781 as Alera, in 803 as Elera, in 1096 as Alara, has two possible derivations: A shortened form of *Eleraha, where *Eler in Old German *olisa or Old Slavic olsa (olsza) would mean Erle ("alder") and aha (pronounced in Acha) is an old word frequently used in river names to mean "water" (cf. the Latin aqua). The name of the tree passed into Low German as Eller, which is very close to the word Aller. Aller would therefore mean something like Erlenwasser i.e. "alder water", which was probably due to the river banks being largely covered in alder trees that prefer wet locations. In Hans Krahe's system of Old European hydronomy, the old name for the Aller, Alara, is an example of a group of river names with the root al-, which is very common over much of Europe and according to Krahe all go back to the Indo-European root *el-/*ol-, which means "flowing". Similarly related would be rivers such as the Alster, Iller, Elz and Ilmenau. Krahe's hypothesis is, however, hotly disputed in language circles. Theo Vennemann used a modified version of Krahe's model in his Vasconic substratum theory.

Flows through: Germany.

River data from Wikidata (CC0); lengths normalised to a common unit.