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(A)
Morphologic development in time
(B)
total deposition / erosion
t
1
N
t
5
t
15
t
45
Q
low
Q
low
sand-ridge
fine silt
deposition
Silt
deposition
channel
scouring
Delta
front
erosion
Channel infill
0
-2
4
0 m
-6
Silt
deposition
-4
-10
(D)
(C)
Morphologic development in time
total deposition / erosion
Silt
deposition
t
1
t
5
t
15
t
45
Q
high
Q
org
Sand-
ridges
sand-ridge
river
mouth bar
Delta
front
erosion
subaqueous
levees
Channel infill
Silt
deposition
2 k
m
Fig. 6.
(A) Morphologic development of the
Q
low
scenario at four distinct time intervals (t in months) and (B) cumulative
sedimentation and erosion at t = 45 months. (C) Morphologic development of the
Q
high
scenario at four distinct time inter-
vals (t in months) and (D) cumulative sedimentation and erosion at t = 45 months. Areas of erosion and deposition that are
notated on the plots are described in further detail in the text.
Wave reworking with low fluvial input (
Q
low
)
For the
Q
low
scenario, the small distributaries are
abandoned and rapidly filled in by silt (Fig. 6A and
B), similar to the Base case scenario. However, the
ongoing discharge in the main distributary channel
prevents it from being filled in by sediments derived
from onshore directed wave-induced transport. Due
to the low discharge, depth-averaged flow velocities
remain under 1 m s
−1
and little scouring occurs.
The initial morphology of the delta is such that
the main distributary is oriented in the northern
direction and it therefore debouches into the basin
under an angle. Asymmetric sand-ridges consisting
predominantly of reworked sand from the delta are
formed at the river mouth; the main distributary
channel carries only little bedload. The offshore
transport of silt by suspended load occurs more dis-
tinctively in the northern area due to the distributary
outflow. Compared to the Base case scenario, a
larger part of the delta plain area is affected by
reworking (compare the red area in Fig. 6B to that in
Fig. 3B). Accordingly, the results suggest that
reworking is more efficient when a wave-influenced
delta is still fed by riverine discharge.
Wave reworking with original fluvial input
(case
Q
high
)
For a discharge of 2000 m
3
/s, which is equal to the
original discharge applied during delta prograda-
tion, some of the smaller distributary channels
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