Pressure-Flow Scour: A Reexamination of the HEC-18 Equation

Abstract

Unsatisfactory features of the equation that is recommended in a standard reference on bridge scour (commonly known as HEC-18) for predicting pressure-flow scour are pointed out. These are found to stem from the basic model of the original regression analysis, which is argued to have suffered from a spurious correlation. An alternative best-fit and a separate design equation are proposed, together with a definition of the region where such equations may be expected to be applicable.