IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Special sessions : New disposal strategy in the schelde-estuary: using dredged sediment to create benefits for nature
New disposal strategy in the schelde-estuary: using dredged sediment to create benefits for nature
To guarantee optimal port accessibility, the deepening of the navigation channel was executed within the scope of the
LongTermVision for the Schelde estuary. As the estuary is part of the Natura 2000 network, both an EIA and AA were
necessary. A new disposal strategy was proposed, using dredged sediments to create opportunities for nature
development. This new strategy was first investigated by Flanders Hydraulics Research, combining several research tools,
and performing 2 in situ disposal tests. After a positive evaluation of the tests, the strategy was further developed, and 4
locations were chosen to apply the strategy to. The main idea of the strategy is using dredged sediments to create
morphological structures that influence the flow patterns, creating low dynamic areas, which are suited for ecological
purposes ("working FOR nature"). Since the 4 locations each have specific characteristics, site-specific relocation
strategies were developed, taking into account local flow and sediment characteristics. For 2 locations at the tip of a
sandbar a "megadune" has been realised, creating a shadow zone behind the megadune. For the other 2 locations
located along a sandbar, a "sandspit" has been realised, aiming at guiding the flow away from the sandbar. To evaluate
the success of this new disposal strategy, an extensive monitoring program was set up and several criteria were defined.
Before the start of the deepening the reference situation was monitored. Since then, new measuring campaigns at all
locations have been executed to evaluate the effect of the works. Recent results show different effects near different
sandbars, both for sediment stability as changes in flow velocities. Nevertheless, ecological results are promising: the first
results show an increase of almost 100 ha new low dynamic habitat. During the following years the new strategy and the
monitoring will continue, allowing the evaluation of the new disposal strategy on the longer term.
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Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Special sessions
Date Published : 21/08/2015
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