عنوان مقاله [English]
The main goal of physical hydraulic modelling of plunge pools as energy dissipators at the toe of reservoir dams is the assessment of their performance efficiency. There is a limitation of using non-cohesive material at steep slopes. Accordingly a suitable combination of cohesive and non-cohesive materials should be selected to simulate the scouring resistance characteristics in the plunge pool against complicated turbulent flow in a hydraulic model. In this study, the relative ability of rock to resist scouring in the plunge pool of Karoon-III dam on the KaroonRiver in south eastern Iran was simulated using a physical model. Eighty-six experiments in four series were carried out in a flume with an effective length of 10 meters with different combination of cohesive and non-cohesive materials, with uniform flow in different velocities. The threshold velocity of scouring was subsequently determined for each combination. Cement was eliminated from the test due to its high scour resistance and was replaced by bentonite clay. Experiments were then continued to determine a suitable fraction of clay bentonite in the combination. The erosive power of water was calculated using three methods: measured flow profiles, flow normal depths, and the Standard Step method. The Erodability Indices were determined by the Annandele method for each method. These Indices were used to determine the suitable class of bentonite clay for different parts of the Karoon-III dam plunge pool.