However, in all these studies only short waves are considered, whereas longer waves generated by wave groups are
expected to play an important role in the hydrodynamics and
sediment transport processes within mangrove systems as
suggested by Massel, Furukawa, and Brinkman (1999). The
mildly sloped mangrove beaches and their even more gently
sloping foreshores create dissipative conditions in which the
incident wind and swell waves dissipate most of their energy
before reaching the shoreline. At the edge of the mangrove
forests the longer infragravity band will therefore already
substantially contribute to the water surface variance.
Within the mangrove forest this effect is enhanced since
longer-period waves such as swells and infragravity waves
are subject to less attenuation, whereas short-period waves
with frequencies related to wind waves lose substantial
energy due to stronger interactions with the vegetation. To
consider the effect of both incident waves and infragravity
waves, the XBeach model was used in this study to provide
insight into the wave attenuation in mangrove forests and to
evaluate the critical value of mangrove width as found for the
east coast of Vietnam in more quantitative terms