Low Sill Control Structure: Physical Modeling Investigation of Riprap Stability Downstream of End Sill

The model investigation reported herein describes the process to model and analyze the stability of scaled riprap in the existing 1:55 Froude-scaled Low Sill Control Structure physical model. The existing model is a fixed-bed model, so modifications were made to create a testing section for the scaled stone. Three separate gradations of scaled riprap were tested at varying boundary conditions (discharge, head and tailwater elevations, and gate openings). Each test was surveyed using lidar for pre to posttest comparisons. It was found that Gradation B remained stable throughout the tests in the physical model.