Irregular Wave Runup on Riprap Revetments

Runup is one of the most important factors affecting the design of revetments exposed to wave action. Generally, riprap revetments are designed so that little or no runup exceeds the top of the protection. In the past this has been a difficult prediction to make, but now a new method for calculating the approximate upper limit of wave runup on riprap has been formulated. This method is based on laboratory data and is easy to apply through use of a recommended or an alternative formula. The recommended formula uses the Airy wavelength, LP, while the alternative formula uses the more standard deep-water wavelength, Lo. The alternative formula provides an easy way to calculate a good ``rule-of-thumb'' estimate for runup. Both formulas can be used to compute the elevation to which protection needs to be extended to prevent exceedance by runup, or used to estimate potential severity of wave overtopping.