Current knowledge of hydro-, sediment and morpho-dynamics in the shore
face environment is insufficient to undertake shoreface-profile evolut
ion modelling on the basis of first physical principles. We propose a
simple, panel-type model to map observed behaviour. The internal dynam
ics are determined by slope-dependent, wave-induced cross-shoreface tr
ansports, while the external driving factors are lateral sediment supp
ly and sea-level rise. This model concept is tested with reasonable su
ccess against the observed behaviour of the Central Holland Coast, con
sidering two hindcast periods, one covering the evolution over the las
t century, the other the Subboreal/Subatlantic evolution. A limitation
of this model is that the cross-shoreface dynamics are solely steered
by the variations of shoaling, short waves. Since a variety of other
wave and current dynamics may be expected to be present in the coastal
boundary layer, it may well be that the effects of the mechanisms and
conditions which are not represented are hidden in the coefficients o
f the sediment-transport formula. This limits the accuracy of the coef
ficients as used, and our findings should be considered as an-order-of
-magnitude estimate only. Indeed, behaviour-oriented modelling implies
that generalization of results to arbitrary situations and conditions
is not straightforward. Yet, we expect that some of the conclusions a
re more generally applicable. This concerns the substantiation of the
assumption that the upper shoreface responds on a much smaller time sc
ale than the lower shoreface, and the idea that the shoreface profile
is not always and everywhere in equilibrium with its forcing. A worthw
hile observation from the Holland Coast application is, that the botto
m slope effect on the transport is only important at geological time s
cales. The profile evolution at the engineering time scales (say 10 to
100 years) is effectively quasi-static, in that there is no feedback
between the long-term averaged transport and the state of the profile.
This implies that at these smaller scales the profile changes can be
predicted on the basis of a static sediment balance. This does not mea
n that the gravitational downslope transport is unimportant as a physi
cal phenomenon in coastal profile evolution: It is only unimportant if
a highly aggregated model like this is applied at relatively short ti
me scales.