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Résumé |
Water waves involve fluxes of momentum and energy
that transport sediment along the shore. The flux
toward shore of alongshore momentum depends on
coastline orientation (relative to the wave propagation
direction). Spatial variations in coastline orientation,
therefore, are associated with gradients in alongshore
sediment flux. Divergences in alongshore sediment
flux cause coastline erosion, and convergences cause
accretion. i.e., coastline shape determines the pattern
of sediment fluxes that in turn change coastline
shape. This ‘morphodynamic’ feedback can produce
instabilities leading to the growth of large-scale
coastline features. In numerical experiments, finiteamplitude
interactions then lead to a variety of
coastline shapes, which are functions of wave climate
(angular distribution). Changes in wave climate arising
from changes in storm climate tend to reshape
coastlines. In a case study, hindcasts of associated
changes in shoreline erosion patterns are consistent
with historical observations, opening up the
possibility to forecast future coastal erosion ‘hot
spots.’ However, on developed coastlines, couplings
between human dynamics and coastline dynamics
must be considered. |
