Author(s): Remi Martinerie; Jean-Louis Boillat; Anton Schleiss; Atefeh Parvaresh Rizi; Alexandre Wohnlich
Linked Author(s): Anton J. Schleiss
Keywords: Extreme floods; Spillway; Flip bucket; Jets; Plunge pool
Abstract: Shahryar dam is currently under construction on the Qezel Owzan River (East Azerbaijan Province) in northwest Iran. An experimental study was led to check the good behaviour of the hydraulic structures during high return period floods. The present paper focuses on the gated spillway analyzing the flow behaviour from upstream towards downstream. The gated spillway is oriented at 45° from the axis of the valley, creating a non uniform approach flow in the left bay of the gated spillway, with apparition of longitudinal vortex close to the left guide wall. To avoid these bad entry conditions, a vertical inclination of the left side wall reveals efficient to distribute uniformly the flow. Furthermore, this inclination allows increasing the hydraulic capacity for high water levels. This effect can be computed by adjusting the left side wall contraction factor. Jets issued from the flip buckets were studied by picture analysis with the aim to define the impact zone in the plunge pool and to protect it against scour. The final design of the gated spillway includes, two splitters located on the flip bucket. Measurements have been carried out with and without splitters to highlight their effect on the jets in each bay. Finally, the model allowed studying the plunge pool behaviour during floods. The jets issued from the gated and crest spillways create a complex and air entraining flow. Velocity and pressure measurements put in evidence the sensitive parts of the plunge pool to be protected against scouring.