Gönnert, G., Graßl, H., Kelletat, D., Kunz, H., Probst, B., von Storch, H ...

GÖNNERT, G./ GRASSL, H./ KELLETAT, D./ KUNZ, H. / PROBST, B./ VON STORCH, H. / SÜNDERMANN, J.
"Klimaänderung und Küstenschutz"
Fig. 5: SPM concentrations in front of the back barrier islands (a, b, c), tidal channels (d, e, f), and
tidal basins (g, h, i). The first column (a, d, g) is from experiment CR, the second (b, e, h) is
from SLR, and the third (c, f, i) is from SLRW25.
One expectation about the contribution of wind waves and sea-level rise to the sediment dynamics in
the entire region of simulations is given by Fig. 6 (the left panel). The resulting sediment response can
be seen in the right panel where we display differential plots between deposition and erosion in some
of the simulations. The general conclusion is that in most of the inlets the sea level rise leads to an
increase of erosion. However, this conclusion is not valid for the Norderney Seegat revealing that estimates
about possible future changes based on simplified models could be wrong in some areas.
There are a number of speculations that sea level rise would increase the erosion of sediment from
tidal basins. Our simulations demonstrate that this is only true in part of the tidal basins, and in particular
in the extensions of inlets. However, the deposition of sediment is enhanced on the tidal flats
and the reason for that is that the tidal asymmetries change as well as the bathymetry. Both effects
could result in reshaping the morphodynamics and in some areas accumulation of sediment would be
possible.
The conclusions about the role of the wind waves are also not trivial. From the bed shear stress shown
in Fig. 6 (left panel) one could expect a trend of erosion of shallow areas and deposition in the deep
ones. This expectation is valid for most of the tidal basins (the right panel). However, the pattern of
deposition minus erosion (D-E) north of the barrier islands indicates that although bed stress due to
wind waves is small everywhere north of the barrier islands the trends of deposition minus erosion are
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