"We all have a short memory when it comes to weather"
Once mighty, violent and capricious, the Durance River was tamed 50 years ago with the building of a giant dam in Serre-Ponçon, 100 kilometres upriver from Cadarache. The dam has created the largest artificial water reservoir in Europe, and the "killer river" has since turned into a mere rivulet, trickling most of the year in its oversized riverbed.
But when heavy rains keep falling, like they have since last Monday, and when that episode coincides with a late snow-melting season in the Southern Alps, the Durance River can quite suddenly return to its old self. It happens less than once in a decade and it's happening now.
Heavy rains, though, are not the direct cause of the present and dramatic increase in the river level. Late last Wednesday night, faced with an alarming rise in the reservoir level, EDF, the French Electric Energy Authority who operates the dam and its hydroelectric plant, had to open the floodgates of the Serre-Ponçon adding 100 cubic meters every second to the already rain-swollen river.
On Monday morning, the floodgates were still open, and they will remain so as long as there's a risk of overflow up in Serre-Ponçon reservoir. As for the weather conditions, which have created this whole situation, they are not as exceptional as they appear. "We all have a very short memory when it comes to the weather. No records have been broken since last Monday," says Bertrand Laviec at Météo-France's regional centre in Aix. After almost six years of severe drought, late spring rainfalls are back — with a bit of excess.