Author(s): Pedro Manso; Marcelo Marques; Fatima Almeida; Alba Canellas; Marcos Botelho
Linked Author(s):
Keywords: Rock scour; Air-water flows; Time-evolution; Model calibration; Prototype surveys
Abstract: Rock scour downstream of dam spillways may endanger spillway operation, dam safety and stability of the valley slopes. It is a complex air-water-rock interaction problem. The paper presents an analysis of the Luiz Carlos Barreto de Carvalho (Estreito) dam plunge pool in Brazil, making use of extensive laboratory and prototype observations to perform a comparative analysis between scour estimation methods. The application of empirical and semi-empirical scour estimation methods specifically to ski-jump jets is discussed and results are compared in terms of ultimate scour depth and time-evolution. The calibration of the scour models is done for periods for which topographic and bathymetric surveys are available, both at the beginning and the end of the period. Calibrated models are then used to predict future scour. The Erodibility Index Method is used, for which a specific “rate of dissipation” model is presented for plunging jets. Such comparative analysis is rarely possible due to the difficulty in finding good-quality input information. Scour model calibration with prototype scour measurements prove to be quite useful in improving the reliability of scour estimates and plunge pool scour follow-up.
Year: 2007