Author(s): E. J. Lesleighter; E. F.R. Bollaert; B. L. McPherson; D. C. Scriven

Linked Author(s): Eric J Lesleighter

Keywords: Spillways; Flood hydraulics; Hydraulic modelling; Numerical modelling; Rock scour; Transients; Numerical analysis; Energy dissipation

Abstract: A number of problems and solutions of rock scour downstream of spillways have been evaluated using a composite approach, based on the gathering of detailed data from a physical model and utilising those data in a sequence of calibration and application of numerical modelling of the scour. Our paper will describe the application of the Computational Scour Model (CSM - Bollaert, 2002 and subsequent) as the numerical procedure that makes the composite approach a proven methodology for such problems. The paper will focus on a case study application of the procedure based on the experiences of flooding and scour at the Paradise Dam, Queensland, Australia. Flooding in 2013 caused substantial scour downstream of the primary spillway. The occurrence led to a series of studies for the evaluation of the geology, and the evident hydraulics behaviour using a well-instrumented physical model to capture pressure and velocity transients, all as part of a process to determine the scour mechanism, and to determine the response of the spillway and areas downstream to future floods of larger magnitude. Utilising the transient data from approximately 60 pressure transducers, ADV measurements for transient velocities, together with the detailed geologic assessment, the comprehensive scour modelling procedures developed by Bollaert were applied for calibration of the numerical model and its application for possible discharge scenarios. The paper will discuss the design and construction of the physical model and instrumentation as a key part of securing adequate data for the composite procedure, and go on to illustrate the outcomes of the CSM procedures.

DOI: https://doi.org/10.15142/T300628160716

Year: 2016