Danube
"Danube" is an Old European river name derived from a Proto-Indo-European "*dānu". Other river names from the same root include the Dunaj, Dzvina/Daugava, Don, Donets, Dnieper, Dniestr, Dysna, Tana and Tuoni. In Rigvedic Sanskrit, "dānu" means "fluid, drop", in Avestan, the same word means "river". In the Rigveda, "Dānu" once appears as the mother of Vrtra, "a dragon blocking the course of the rivers." The Finnish word for Danube is Tonava, which is most likely derived from the word for the river in Swedish and German, "Donau". Its Sámi name "Deatnu" means "Great River". It is possible that "dānu" in Scythian as in Avestan was a generic word for "river": "Dnieper" and "Dniestr", from "Danapris" and "Danastius", are presumed to continue Scythian "*dānu apara" "far river" and "*dānu nazdya-" "near river", respectively.
Vienna Danube regulation
After repeated severe flooding, in 1810 Hofbau-Direktor Josef von Schemerl proposed regulating the river by creating a new river bed, but his plans were not realized. From 1870 to 1875 the Danube was regulated for the first time. On the left bank, a wide flood-prone area, the "Inundationsgebiet", was created with the dam Hubertusallee covering today's municipal districts of Floridsdorf and Donaustadt. The new main branch, including shipping, was wide, leaving the old river bed as the Old Danube. Additional major floods in the years 1897, 1899 and 1954, especially concerning the right bank of the Danube at "Handelskai" ("Trade pier"), proved that this 1875 regulation of the Danube was insufficient.