Development of Labyrinth Spillway Designs

Spillways have a major influence on dam safety and their cost represents a significant part of the total project cost. Reports show that almost one third of dam failures have been caused by insufficient spillway capacities. Generally speaking, the selection of the spillway design flood is a socio-economic decision. In developing countries, with priority given to agricultural production, spillway design flood might have a low return period. Whereas in developed countries, spillways of large dams are designed to pass the probable maximum flood (p. m. f. ). Using this criterion, more than 30,000 dams in the USA have been categorized as uncertain. Labyrinth spillway designs are described in the article. Hydraulic performance and hydraulic tests are also described.