Wave setup and runup: An integrated approach

Abstract

By extending and sharpening the usual definitions of water depth and mean water level throughout the swash zone, it is shown that the elevation of the shore line on an impermeable beach is logically at the runup limit, not at the average water-line level. Thus, the runup limit becomes a point on the setup profile, and this leads to a significant expansion of the experimental information on setup which can be extracted from the existing literature. From the experimental data base, thus extended, a first approximation to a universal description of setup profiles is derived, i.e. the most appropriate vertical and horizontal scaling parameters are suggested for the shape of the mean water surface in the inner surf zone. Existing setup data show that traditional, simplistic setup models ∗ ∗ e.g. Bowen et al. (1968). are inadequate for modelling the shape of the most landward part of the mean water surface and hence for predicting the shoreline setup. Instead, it is suggested to base estimates of the shoreline setup on the relation between this quantity and the maximum runup height together with well-proven runup formulae. The validity of this approach needs to be established quantitatively however, through simultaneous measurements of runup and mean water surface on/in natural beaches.