ConnectING 19 juni 2022

DUNE IN FRONT OF DIKE:
BUILDING COASTAL RESILIENCE
At Bruges Campus, the Coastal and Geotechnical Engineering
group is world-renowned for its research into the interaction
between soil, water, and structures. On 12 and 13 April,
the group again lived up to its reputation by organizing the
very first conference on nature-based solutions for coastal
protection in Belgium. We look back with Prof. Pieter
Rauwoens, Conference Chair
“ Last year, during the Coastal Dynamics
Conference at TU Delft, we presented
the pilot project Dune in front of Dike
for the first time,” says Prof. Rauwoens.
“The interest was so great that we decided
to devote a conference to it ourselves. This
resulted in a two-day event during which not
only we but also eleven other international
experts presented their advances in building
resilient coastal infrastructure. In addition,
22 research posters were presented.
We welcomed 57 participants, 48 of whom
were on campus and 9 online”.
Pilot projects
The first conference day focused on the
pilot projects of Bruges Campus on the
Belgian coast. “Our project partners were
given an important role here,” continues
Prof. Rauwoens. “Daphné Thoon of
Flanders’ Coastal Division explained how
dunes can form a natural defence against
flooding and coastal erosion. What is new
here is the use of natural elements and
processes in the formation of new dune
areas to reinforce traditional sea dikes.
Such dunes in front of a dike offer a high
level of protection of coastal infrastructure
as well as a high ecological value and – last
but not least – a nicer natural appearance”.
Toon Verwaest of Flanders Hydraulics
Research elaborated on the added value
and monitoring of the pilot projects in terms
of coastal defence, morphological stability,
ecology, and tourism. Glenn Strypsteen,
researcher at Bruges Campus, then
presented his model for predicting dune
growth. By means of weekly topographical
measurements, he monitored the growth
and profile shape of the dune. He also
mapped out the role that the vegetation
can play in dune development. Dries Bonte
(Ghent University) illustrated the importance
thereof using marram grass. This plant
proved to be an excellent natural engineer
to prevent the sand on the beach from
being blown away. The extent to which
the marram grass increases in density and
spreads over the beach greatly influences
the creation and growth of new dunes.
Engineering with nature
The second conference day was reserved
for the international researchers. Prof. Jean
Taylor Ellis of the University of South
Carolina kicked off the event with a
keynote on 'Engineering with Nature for
Coastal Engineering Purposes'. “So-called
'soft' interventions are gaining in
importance compared to classical hard
engineering structures such as sea walls
and dikes,” Prof. Rauwoens explains.
“In the context of the climate change,
these expensive and hard to adapt
structures will not resist future flood
events, which means that more innovative
solutions such as dune-in-front-of-dike will
be required”.
Francisco Tavaro-Pinto (University of Porto),
Caroline Hallin (TU Delft), Björn Mehrtens
(TU Braunschweig) and Hendrik Vinge
Karlsson (Danish Coastal Authority)
explained how coastal protection by
dunes is achieved naturally elsewhere in
Europe. Whereas in Portugal there is a
shortage of sand, in Denmark there is a
problem of dunes moving inland and
bogging down the coastal roads.
Finally, Marien Boers of Deltares presented
a model to calculate the strength of dikes
that are partially or completely covered
with sand. The idea is that during a storm,
the sand will get the full brunt of the storm
so that the dike will not be damaged.
Site visit
The conference ended with a visit to the
pilot projects. On the beach in Ostend,
an area of 2400 m² of marram grass was
planted with the intention of retaining
as much sand as possible so that, in time,
a natural dune will form. “The project
uses the forces of nature to protect the
coast from storms and the consequences
of climate change,” concludes Prof.
Rauwoens. “Moreover, dunes are a
unique ecosystem that contain a wealth
of biodiversity. So, with our pilot projects,
we score on multiple fronts”.
Yves Persoons
CONNECTING
39