Italian Dam Failures – Important Lessons Learned from Failure of Gleno Dam (1923) and Overtopping of Vajont Dam (1963)

Two significant dam catastrophes occurred last century in Northern Italy: Gleno Dam in 1923 and Vajont Dam in 1963. Both of these failures resulted in high loss of life, emphasizing the importance of dam safety in the world, and leading to future practices to prevent such catastrophic failures.

Gleno Dam, a multiple arch buttress dam, was constructed between 1916 and 1923 primarily to produce hydroelectric power. Forty (40) days after first filling, a buttress on the dam cracked and subsequently failed monoliths in the middle section of dam. This fast-forming sunny-day breach caused a large flood wave to flood several villages below, killing at least 365 people.

One of the tallest dams in the world at 860-feet, the double-curved, thin-arch Vajont Dam was constructed between 1957 and 1960. During initial filling in 1963, a landslide caused a mega-tsunami in the lake in which over 40,000 acre-feet of water overtopped the dam. This large overtopping volume caused a flood wave estimated at over 800 feet tall just below the dam which propagated downstream causing massive flooding and destruction to the valley below. Several villages and towns were destroyed with an estimated 1,900 to 2,500 deaths.

An overview of these catastrophes and the important lessons learned will be presented, linking to Italian Dam Safety as well as discussing the human factors that contributed to the catastrophes, leveraging previously developed information from prior papers and presentations.