Erosion is calculated for each layer (dz) shown in Fig. 2. The rock profile
is eroded by wave action (where wave transformation is described
using linear wave theory; Kamphuis, 1992; Kamphuis, 2000), the vertical
influence of which fluctuates with the tidal cycle. Fig. 3 illustrates the
conceptual shore profile and the integration of erosive potential for a
single semi-diurnal time-step. At every stage, the breaking wave field
has the potential to erode the submarine rock surface, represented by
the erosion shape function (f1), a dimensionless distribution derived
from physical model tests by Skafel (1995) in which pseudo-random
waves shoaled and broke over a glacial till shore.While the results relate
to this specific lithology it seems reasonable to suppose that the relative
distribution of wave scour will be similar regardless of lithology. Furthermore,
while the expression does not consider swash, this zone
typically contains small and therefore less powerful/significant waves.
The seaward extent of f1 is approximately equal to the depth at which
waves begin to break.