I am currently looking into the land reclamation projects done in The Netherlands, England and France. I've come across something called a "Bateau Vanne" in France. It is used to clean sewers from the sludge that accumulates at the bottom by creating a water level difference by means of the plate in the picture. The force of the water difference is channeled and used to disturb the sediment.

Picture is of a modern day Bateau Vanne, but the technique is the same as used in the 16th-17th century. http://luc78960.free.fr/TPE/Dysfonctionnement/im/i/bateau-vanne.jpg

I've come across sources that suggest this technique was brought to France by Dutch engineers (whom used it in the Polder canals) during the 16th / 17th century but my research has reached a dead end. Is there someone with some additional knowledge on this subject?