Loire - Discharge and Flood Regulation

Discharge and Flood Regulation

The river has a discharge rate of 863 m3/s (30,500 cu ft/s), which is an average over the period 1967–2008. The discharge rate varies strongly along the river, with roughly 350 m3/s (12,000 cu ft/s) at Orléans and 900 m3/s (32,000 cu ft/s) at the mouth. It also depends strongly on the season, and the flow of only 10 m3/s (350 cu ft/s) is not uncommon in August–September near Orléans. During floods, which usually occur in February–March but also in other periods, the flow sometimes exceeds 2,000 m3/s (71,000 cu ft/s) for the Upper Loire and 8,000 m3/s (280,000 cu ft/s) in Lower Loire. The most serious floods occurred in 1856, 1866 and 1911. Unlike most other rivers in western Europe, there are very few dams or locks creating obstacles to its natural flow. The flow is partly regulated by three dams: Grangent Dam and Villerest Dam on the Loire and Naussac Dam on the Allier River. The Villerest dam, built in 1985 a few kilometres south of Roanne, has played a key-role in preventing recent flooding. As a result, the Loire is a very popular river for boating excursions, flowing through a pastoral countryside, past limestone cliffs and historic castles. Four nuclear power plants are located on the river: Belleville, Chinon, Dampierre and Saint-Laurent.