1.
Pile hula
Concrete columns, which are
found in many ports, are very
useful for what we have called pile
hulas. These are nylon strips that
look like Hawaiian skirts when
they are attached to columns and
piles. In almost no time, they are
colonised by mussels, barnacles
and a range of algae. A pilot study
in Rotterdam harbour showed
that an average of 8.5 times
more biomass is found on the
pile hulas than on ordinary piles.
These shellfish also improve water
quality because they filter the
water to collect food.
‘
Building with nature’ comes in many shapes
and forms. In principle, it is feasible anywhere:
urban or non-urban settings, rivers or coasts,
large or small spaces...
EXAMPLES OF
'
BUILDING
WITH NATURE’
2.
Pontoon hula
This is a variation on the pile hula.
It is a floating structure made from
PVC that can be used in harbours.
Ropes hang down from it that, as with
a pile hula, are rapidly colonised by
a range of organisms that filter the
water and improve water quality. Trials
in the Delta Flume at Deltares have
shown that the pontoon hulas are
also excellent structures for damping
reflection waves in harbours.
3.
Rich dike
Simple and cheap changes to hard
structures like dikes, piers and dams
can be used to retain water in higher-
lying parts of intertidal areas, resulting
in an enormous boost for local
biodiversity. This makes it possible
to create pools at the foot of the dike
without affecting flood prevention.
Birds and other marine animals feed
on the organisms in the pools, which
also enhance the recreational and
educational value of the area.
4.
Eco-concrete
Modern concrete is becoming much
smoother, and so it is much less
amenable as a habitat for many
marine animals that like hard
sub-surfaces. Eco-concrete can be
a solution. It has a special texture
that allows organisms such as
algae, seaweed, periwinkles and
mussels to colonise it more easily.
A pilot study has shown that eco-
concrete with a rough surface will
be covered much more quickly by
algae than smooth concrete and
that mussels and periwinkles prefer
it. On top of the ecological benefits,
eco-concrete also makes water
cleaner and clearer because the
mussel colonies filter the water.
14
DOSSIER BUILDING WITH NATURE