To correct Equation 7.17 for abutments skewed to the stream, use K2 for Equation 7.16.
Clear-Water Scour at an Abutment. Use Equations 7.16 or 7.17 for live-bed scour because
clear-water scour equations potentially decreases scour at abutments due to the presence of
coarser material. This decrease is unsubstantiated by field data.
7.9 SCOUR PROBLEMS
Solved problems for contraction, pier, and abutment scour in metric (SI) and English units
are given in HEC-18 (Richardson and Davis 2001). Example problems for stream instability
problems are given in HEC-20 (Lagasse et al. 2001a). In addition, guidelines for the design
of scour and stream instability countermeasures are given in HEC-23 (Lagasse et al. 2001b).
In Chapter 10 of this manual, three design examples are given which demonstrate the use of
some of the equations and methods given in this chapter.