Table 2: Frequency of occurrence of dam failures reported in the literature (after www.ence.umd.edu, August 1999)

Area Reference No. of Failures Total Dam Years (x10-3) Failure Rate
USA Gruner (1963, 1967) 33 71.0 5 x 10-4
Babb & Mermel (1968) 12 43.0 3 x 10-4
USCOLD (1975) 74 113.0 7 x 10-4
Mark & Stuart-Alexander (1977) 1 4.5 2 x 10-4
World Mark & Stuart-Alexander (1977) 125 300.0 4 x 10-4
Middlebrooks (1953) and Mark & Stuart-Alexander (1977) 9 47.0 2 x 10-4
Japan Takase (1967) 1046 30 000.0 4 x 10-5
Spain Gruner (1967) 150 235.0 6 x 10-4
Overall Average Dam Failure Rate 4 x 10-4