Wave Cuts in Sand Slopes Applied to Coastal Models

Abstract

In selected laboratory tests of sand slope development by waves, the elevations of two types of subaqueous wave‐cut feature are explained by quantitative thresholds in wave‐sand interactions. One feature is a seaward limit to nearshore‐eroding wave processes, and the other is a seaward limit to constructive wave effects. These two calculable water depths usually define the extent of moderate sand agitation by shoaling waves. The basic type of wavedeveloped profile is found to depend on sand settling velocity and wave characteristics at the erosive wave cut, but not on details of surf processes as measured by a surf‐similarity number. These results, together with available knowledge of the equilibrium profile, are examined to define some requirements for an accurate model of the active nearshore sediment bed. With quartz sand in water and Froude‐scaled waves, a model would require an unusually long and deep wave tank. Several modeling compromises appear necessary in the planar profile segment of moderate bed agitation, so that restricting laboratory models to the curved shoreface profile segment seems advisable.