Revisiting Riprap Sizing Relationships for Overtopping Flow Conditions

Abstract

This technical note briefly reviews existing empirical riprap sizing equations for overtopping flow conditions. It then proposes new riprap sizing relationships that focus on the dominant parameters of bed slope and unit discharge. These new equations avoid shortcomings of previous equations while achieving similar performance statistics. This technical note also explores riprap sizing relationships that incorporate other riprap properties, including relative riprap thickness, coefficient of uniformity, specific gravity, and angle of repose; however, these equations do not provide a definite improvement over the equations using only bed slope and unit discharge, and the equation parameter values are not clearly unique.