- (river)The Senne is the river on which Brussels was founded. The name derives from the Celtic "Sonia." It was also called "Sin" in some early sources.The Senne rises in the province of Hainault and flows through the city from southwest to northeast into the Rupel River, a tributary of the Schelde. It runs for 103 km (64 mi.) At the site of Brussels, the river flowed around three islands: the Île Saint-Géry or Grand Île, the largest; the Petite Île or Île d'Overmolen; and the Île des Chevaliers. The river has four main tributaries; the Maelbeek, Molenbeek, Pede, and Geleytsbeek streams.Brussels developed at the site where the Senne was no longer navigable and goods had to be unloaded onto ground transport. The three small islands at this juncture also afforded an easily defensible position for a settlement.Until the 16th century, the Senne served as Brussels only navigable artery. In 1434, the river was deepened and straightened to facilitate ships' passage. The construction of the Willebroeck Canal (1531) reduced the river's commercial role. Following the linkage of the canal with the newly constructed Brussels-Charleroi Canal (1832) the Senne was no longer needed for transporting goods.In addition the river was a capricious stream subject at times to flooding and drought-induced low levels. A devastating flood inundated several city districts on 15 August 1850. It also underwent progressive silting up. By the mid-19th century, the Senne had become much polluted—a cholera epidemic in May 1866 killed an estimated 3,467 people — and, in the interests of public health, it was canalized and vaulted over between 1867 and 1874 and modern boulevards were built.
Historical Dictionary of Brussels. Paul F. State.