Inflatable Dike

Paris will stage a "flood drill" over the next 2 weeks, simulating the Seine river rising to the level (over 8 meters) of the worst flood of recorded history, in 1910.  This major simulation will involve fire departments, the police force, schools, museums, the electric company, etc...
As part of the process, they demonstrated this movable and inflatable dike.  By the time I got there, it was being packed up for another showing later this week.  It is 500 meters long, and when filled with water, it weighs 1 ton per 100 meters.  And should therefore contribute to holding back the high waters of the Seine.