Riprap Design for SAF Stilling Basins

Abstract

Physical model tests were conducted to determine criteria for the size and placement of riprap downstream of SAF stilling basins to ensure basin integrity. Relationships are presented to determine the depth, width, and length for preformed scour holes as a function of the Froude number and riprap size. Results show that the riprap size required for stability increases exponentially with Froude number. Smaller riprap is required for stability if the riprap is recessed below the elevation of the basin floor. For level riprap placement, larger riprap is required for stability when the riprap is placed at the end sill elevation compared to placement at the basin floor elevation.