Investigation of the Impact of Cell Excavation on the Performance of Piano Key Weirs Spillways – Type (A) – for Enhancing Flood Protection and Dam Safety

Piano Key Weirs (PKWs), particularly non-rectilinear spillways, play a crucial role in flood control and dam discharge management, significantly improving both discharge capacity and storage potential for new and existing dams. These innovative structures were developed by Ouamane and Lempérière between 2003 and 2006, introducing a unique design compared to conventional labyrinth spillways. Characterized by their non-rectilinear geometry, PKWs feature rectangular cells and sloping riffles that optimize water flow.The PKW Type A spillway design includes three key cell configurations: (1) basic rectangular cells without modifications, (2) symmetrical widening of both upstream and downstream cells, and (3) asymmetrical widening of either the upstream or downstream cells.This study, conducted on the PKW Type A at the M’anab El Ghoulal Dam in Biskra, Algeria, experimentally investigates the impact of cell widening on the hydraulic performance of PKW Type A to enhance flood protection and dam safety. The results demonstrate that increasing cell width significantly boosts discharge capacity compared to configurations without parapet walls. The performance improvement is particularly influenced by the ratio of cell depth to the spillway's maximum height. Among the tested designs, the PKW Type A with symmetrical parapet walls exhibited the highest efficiency, followed by models with upstream-only parapet walls, and finally those with downstream-only walls. These findings provide valuable insights into optimizing PKW designs for improved flood resilience and dam protection.