Between a Rock and a Soft Place: Which Riprap Method Should I Use for My Project?

Riprap is one of the most commonly used methods for channel stabilization (both bank and bottom). Presently, there are many riprap design methods used in the United States. Some of the prominent methods are the U.S. Army Corps of Engineers, U.S. Bureau of Reclamation, U.S. Geological Survey, California Bank and Shore Protection, Federal Highway Administration, Isbash, and ASCE. This paper briefly discusses each of these methods, the theory and data used in their development, recommendations on their usage made by their developers, and the observations and recommendations of the authors of this paper. To illustrate these points, hypothetical examples are presented and a computer program is used to easily make comparisons between these seven methods. These examples are utilized to properly interpret the applicable range for each method and assist in the decision of which method to use. This was done by examining the results of combinations of shear force and velocity versus the representative (D₅₀) riprap size for each method.