Hydraulics of Piano Key Weirs: A review

The Piano Key Weir (PKW) is a rectangular-labyrinth-type weir that utilizes cantilevered apexes in order to maximize the allowable weir length that can fit in a given spillway channel width, while reducing the required structural footprint. These features make it an interesting and viable solution for increasing discharge capacity at existing dams as well as new projects. Since the early works at the University of Biskra in 2000, numerous re-search and development works have been carried out in several laboratories to understand the PKW hydraulic behavior, optimize its design and prove its advantages and drawbacks. Beside, more than 25 PKWs are now in operation or under construction all over the world. This paper aims at summarizing the information available to date about PKW hydraulics in order to provide a synthetic overview and a reference list to students, researchers and practitioners and thus help them to understand how such a complex structure operates and what could be the possible further steps in research and development.