Coastal Engineering 52 (2005) 285 302
Prediction of swash motion and run-up including the effects of
Li Erikson*, Magnus Larson, Hans Hanson
Department of Water Resources Engineering, Lund University, Box 188, 221 00, Lund, Sweden
Received 5 February 2004; received in revised form 4 May 2004; accepted 14 December 2004
Modifications to a model describing swash motion based on solutions to the non-linear shallow water equations were made
to account for interaction between up-rush and back-wash at the still water shoreline and within the swash zone. Inputs to the
model are wave heights and arrival times at the still water shoreline. The model was tested against wave groups representing
idealized vessel-generated wave trains run in a small wave tank experiment. Accounting for swash interaction markedly
improved results with respect to the maximum run-up length for cases with rather gentle foreshore slopes (tanb=0.07). For the
case with a steep foreshore slope (tanb=0.20) there was very little improvement compared to model results if swash interaction
was not accounted for. In addition, an equation was developed to predict the onset and degree of swash interaction including the
D 2005 Elsevier B.V. All rights reserved.
Keywords: Run-up; Swash; Wave groups; Vessel-generated waves; Ballistic model
depending on the incident waves and foreshore slope.
There have also been several observations and
attempts to describe interaction between subsequent
Modeling of the hydrodynamics in the swash zone
has seen many advances in recent years. It is now
Puleo (2001) recently showed that the presence or
fairly well established that swash motion is driven by
lack of swash collisions might describe whether
low frequency infra-gravity motions and bores which
foreshores accrete or erode (this was also suggested
collapse at the shoreline and then propagate up the
beach face. The two mechanisms do not appear to be
excursion times are of longer duration than the
exclusive, but rather, one dominates over the other
incident wave period, steepening is expected to occur.
In contrast, on beaches where the swash is of shorter
duration than the incoming bores, erosion is expected
* Corresponding author. Tel.: +1 831 476 8582.
to occur and the foreshore will be flattened.
E-mail address: firstname.lastname@example.org (L. Erikson).
0378-3839/$ - see front matter D 2005 Elsevier B.V. All rights reserved.