Using turbulence to keep dams clean

20. Sediment builds up in reservoir water and can prevent dams from operating properly. EPFL researchers have come up with a method of keeping sediment in suspension and allowing it be flushed out. All dams on earth, from the Mauvoisin Dam in Valais Canton to the Xiaowan Dam in China, have the same problem: sediment accumulating in the reservoir. This situation is commonly addressed by 'dead storage' capacity at the bottom of the reservoir, where alluvium is able to settle. But if these silt deposits are never cleared out, the reservoir will become blocked in as little as a few decades and turn into a sandy beach. A team from EPFL has developed a clever way to address this problem: submerged water jets create turbulence that keeps tiny sediment particles in suspension so that they can be carried away through the dam's water turbines.