W orking to g e th e r on innovative m o n ito rin g strategies: adapting to
nature, huge demands and grand challenges
Van Lancker Verala, Matthias Baeyela, Frederic Franckenla, Dries Van den Eyndela, D im itris
Evangelinos2, Ilse De Mesellb, Francis K erckhoflb, Reinhilde Van den Brandenlb and Lieven N audtslb
1 Royal Belgian Institute o f Natural Sciences
“Operational D irectorate Natural Environment, Gulledelle 100, B-1200 Brussels, Belgium
bO perational Directorate Natural Environm ent, Bde en 23ste Linieregim entsplein, B-8400
Oostende, Belgium
E-mail: vera.vanlancker@ mumm.ac.be
2 MSc Marine and Lacustrine Science and Management (Oceans & Lakes), Pleinlaan 2,
B-1050 Brussels, Belgium
Socio-economic dem ands fo r marine aggregate resources have increased at an unprecedented pace.
For the A tla n tic region, hundreds o f m illion s m 3 o f offshore sand and gravel have been extracted fo r
coastal maintenance, harbour extensions and onshore industrial use. Still, we are facing grand
challenges, fo r which aggregate demands w ill be even higher. First, increasing volum es o f
nourishm ent sand are needed as accelerating sea-level rise w ill leave our coastlines ever more
vulnerable. Secondly, vast quantities o f sand and gravel w ill have to be extracted to realize the large
infra structu ra l w orks th a t are the key com ponents o f many visions on coastal zone and offshore
developm ent. Meanwhile, nature protection is increasing as well, and appropriate assessments are
needed o f the environm ental impacts.
The fa r offshore H inder Banks are targeted fo r e x p lo ita tio n o f huge quantities o f sand, m ainly fo r
coastal defence w orks. Here, up to to 2.9 m illion m 3 can be taken over 3 m onths, w ith a m axim um
o f 35 m illion m 3 over a period o f 10 years. Large vessels can be used e xtra cting 1 2500m 3 per run.
Present-day yearly extraction levels recently surpassed 3 m illion m3, the m ajority o f which was
extracted w ith vessels o f 1500m 3. South o f the H inder Banks concession, a H abitat Directive area is
present, hosting ecologically valuable gravel beds. For these, it is critical to assess the effect o f
m ultiple and freq ue n t depositions from dredging-induced sedim ent plumes.
How will n ature react?
We anticipated w ith a m on itoring strategy, ta ilo re d fo r assessing the im portance and e xten t o f
perturbations th a t are created by the e xtra ction activities. Our m on itoring design is focussed on
hydrodynam ics and sedim ent tra n sp o rt w ith feedback loops between both m odelling and field
studies. Main targets are assessing changes in seafloor in te g rity and hydrographic conditions, tw o
key descriptors o f marine environm ental status w ithin Europe’s Marine Strategy Framework
Directive.
State-of-the-art instru m e ntatio n (from RV Belgica) is used, to measure the 3D cu rren t structure,
tu rb id ity , depth, backscatter and particle size o f the m aterial in the w ater colum n, both in-situ and
w hilst sailing transects over the sandbanks. In the Habitat Directive Area, gravel bed in te g rity (i.e.,
epifauna; sand/gravel ratio; patchiness) is measured as well. Most innovatively, an autonom ous
underw ater vehicle was deployed (Wave Glider, Liquid Robotics), resulting in 24 days o f current and
tu rb id ity data.
From a firs t data-m odel integration, and analyses against hydro-m eteorological databases, main
results show: (1) high spatial and tem poral va ria b ility o f tu rb id ity , unexpected in the so-called
‘clear’ w aters o f the H inder Banks; (2) im p o rta n t resuspension by waves, regardless the area being
considered as ‘deep’; (3) spreading and deposition o f sedim ent plumes; and (4) com petitiveness o f
ebb and flood, m eaning th a t the potential fo r sedim ent deposition to the south is high. Plume
dispersion mechanisms and pathways are now estim ated and modelled.
Data w ill be integrated w ith results from the m orphological and biological m on itoring , respectively
carried o ut by the C ontinental Shelf Service o f FPS Economy and the Institute fo r A g ric u ltu ra l and
Fisheries Research. Together, te m p ora l and spatial patterns, scale and processes can be resolved
and interlinked w ith pressures and system vulnerability.
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