Experimental investigations on plunge pool protection measures for Ilarion Dam in Greece

Ilarion Dam is a 130 m high earthfill dam at Aliakmon River in northern Greece. The dam was commissioned in 2010. It has two spillway tunnels with ski jumps at the outlets. The two spillways are designed to release a total discharge of 5'500 m3/s during the probable maximum flood (PMF). During the flood events in 2013 and 2015, where only one spillway was working, scour holes have formed inside the plunge pool and erosion was observed at its banks and further down the tailrace channel. After a series of preliminary numerical investigations on the hydrodynamic behavior of the plunging jets, a physical model was built to assess the stability of prims protection carpets mitigate further scour of the plunge pool.