Optimizing the Piano Key weir using numerical and physical models

The Piano Key weir (PK weir) provides a good compromise between high discharge capacity needs and the available limited width at many dam sites. In addition, its ease-of-use and low cost compared with gated weirs make it an interesting solution. An additional advantage of PK weirs is that they can be used as a discharge or protective structure for channels and run-of-river hydro plants. These benefits have prompted several research laboratories and organizations to carry out hydraulic studies and tests on physical models to define the optimal form of PK weir. However, numerical modelling of the flow over PK weirs, which may help in the preliminary design of the structures, has only been the subject of a few studies, mainly undertaken by EDF of France.