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Welcomes you to the Icebreaker Party

High resolution topo-bathymetric and flow measurements and 2D-hydrodynamic numerical modelling to evaluate the effects of the deepening of the navigation channel in the Western Scheldt

Yves Plancke (Antwerp Maritime Academy, Flanders Hydraulics Research); Dries Vertommen (MDK – Flemish Hydrography); Kirsten Beirinckx (MOW – Maritime Access); Gwendy Vos (MOW – Flanders Hydraulics Research, Antea)

 

To guarantee optimal port accessibility, one of the projects within

the scope of the LongTermVision for the Scheldt estuary to be

executed, is the deepening of the navigation channel. The

environmental impact assessment and an appropriate assessment

concluded that a new disposal strategy should be applied: the dredged

material has to be disposed near sandbars at 4 locations, to create

new ecological valuable habitats.

 

To evaluate the success of this new disposal strategy an extensive

monitoring programme was set up and several criteria were defined.

Frequent (2-weekly, monthly) topo-bathymetric surveys using multibeam

echo sounding are performed in combination with seasonal

sedimentation-erosion measurements using both RTK (intertidal) and

singlebeam (subtidal). Also flow velocities on 10 transects, each

consisting of 4 measurements points, in the shallow subtidal and the

intertidal zone near the disposal locations are monitored using

ADP’s (Nortek – AquaDopp). The ADCP devices on the intertidal zone

were dug in the sandbar and look upward, allowing maximal vertical

resolution when flooded during the tidal cycle.

 

Parallel with the monitoring, a validated 2D-numerical hydrodynamic

model was used to evaluate the effects of the disposal of sediments.

Every three months, a simulation is performed using the most recent

topo-bathymetry. This allows an evaluation of the changes in flow

velocities and flow patterns near the disposal areas.

 

On a monthly basis monitoring results are assessed by a group of

internal experts. Based on these results, the disposal strategy is

optimised. Preliminary results show different results for each

location, although in general the stability of the disposed sediment

is satisfactory. After 2 years a first evaluation will be executed on

the success of the new disposal strategy. This evaluation will be

screened by a group of external experts.