A Dredging and Disposal Strategy
for Managing the Western Scheldt’s
Morphology and Ecology
By Jean Jacques Peters (Port of Antwerp Expert Team)
Co-authors:
• Youri Meersschaut (Hydraulic Laboratory)
• Yves Plancke (Port of Antwerp Authority)
• Reg Parker (Port of Antwerp Expert Team)
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
The Western Scheldt
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
The debate
• A degradation of the environmental values of
the Scheldt estuary was observed
• The Westerschelde could evolve further from
a multi-channel to a single-channel system
• Danger of flooding increases with stronger
and faster propagation of the tidal wave
• More dredging is needed for improving the
navigation conditions
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
The questions
• Ecologists blame dredging for the degradation
of the estuarine environment, but how does
ecology relate to morphology?
• What has caused the morphological
changes in the estuary?
• Can we use dredging to curb the negative
evolution in the morphological changes?
• Can we consider “morphological dredging”
as part of a solution for the morphological
management of the estuary?
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
Morphological changes (1636 - 1800)
1636
Natural sedimentation and land reclamation
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
Morphological changes (1800 - 1938)
Land reclamation & cutting off side branches
No significant dredging
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
Morphological changes (1938 - 1972)
Limited dredging but still very
significant morphological changes
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
Morphological changes (1972 - 1997)
Increased dredging but almost no
significant fluviomorphological changes
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
What did we learn?
• Reclaiming land, establishing polders, cutting
off side branches made the river morphology
change much more than dredging does today
• In some areas, the shape of sandbars is not
adequate for keeping a “healthy” multichannel system
• Morphological management should aim at
correcting the shape of the multi-channel
system: adapting channels, sandbars, tidal
flats, hard bordering
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
The “Walsoorden” project
Approach by combining different tools
 Analysis of historical data
 Field measurements
 Physical scale modelling
 Numerical modelling
 In situ test: conducting a well monitored
disposal experiment
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
Field
surveys
Sedimenttransport (DB): Kaloo MP1
10
50cm
40cm
20cm
10cm
30cm
HW
LW
Sediment Volume [cc per 300 sec]
8
6
4
2
Port of Antwerp Expert Team
0
7:00
8:00
9:00
QuickTime™QuickTime™
and a
a
10:00
11:00
12:00
13:00 and14:00
Photo
- JPEG
decompressor
Photo
- JPEG decompressor
Time
are needed toare
see
this picture.
needed
to see this picture.
15:00
16:00
17:00
18:00
19:00
20:00
Numerical model
Port of Antwerp Expert Team
Physical scale model
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
Mobile-bed scale model
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
Measurements – 1998-2002
Simulations
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
Technical feasibility
• Hopper + pipeline +
system for disposing
the dredged material
on the riverbed
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
But …
• Morphological dredging and disposal of
sediments is only one of the tools, used to
redistribute the sediment
• The “hard bordering” of the estuary too
needs to be adapted
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
Adapting the navigation channel?
At present
Future?
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.
Adapting the navigation channel?
Adapting lay-out of the hard bordering (retreat/advance), modifying
the shape of sandbars by dredging and sediment disposal.
Port of Antwerp Expert Team
QuickTime™QuickTime™
and a
and a
Photo - JPEGPhoto
decompressor
- JPEG decompressor
are needed toare
see
this picture.
needed
to see this picture.