Within
the structure of the European Water Framework Directive (WFD), an integrated
river basin management scheme for Europe, the Rijkswaterstaat (the powerful
Dutch Ministry of Infrastructure and the Environment) has, between 2010 and
2013, been involved with the clean-up of the river beds within the Dordtse
Biesbosch.
This was
mainly necessary due to the aftermath of the Industrial revolution and the
closure in 1970 of the Haringvliet (using a mixture of dams and sluices)
causing a build-up of heavily polluted silt transported via the Rhine and
the Maas settling as sediment in the Biesbosch and the Haringvliet.
Pollution
The
polluted silt consisted mainly of heavy metals such as zinc, arsenic,
copper, nickel, mercury, cadmium and lead together with poisonous chemicals
such as PCB’s (Polychlorinated Biphenyls) and HCB (Hexachlorobenzene) (See
also the section concerning the Cormorant colonies)
What was
involved in the clean-up?
The
clean-up involved either the removal of the polluted silt from the river
beds and replacement with clean ground or the covering of the polluted silt
with a clean layer of ground.
What has
been cleaned?
The
Dordtse Biesbosch is approximately 700 hectares in size, of which about 300
hectares consists of large, medium and small sized creeks. About 135
hectares of these creeks have, in the past 15-20 years, been cleaned by a
natural process of sedimentation of cleaner silt. About 95 hectares have
been cleaned by a combination of dredging and coverage of polluted silt.
About 95 hectares have been cleaned-up exclusively by coverage of polluted
silt, but because of the vulnerability of some natural areas a number of
middle and small sized creeks have not been cleaned-up.
The
clean-up has been carried out in an area covered by the Moerdijk bridges,
the Spoorslootgriend (Reed beds on the edge of the railway), a part of the
Lepelaarsgat (literally Spoonbill Creek), the larger creeks of the
Zuid-Maartensgat, the Zeehondengat (literally Seal Creek), the Gat van
Noorderels and the Noordediep and the middle sized creeks of the Zuidgat and
a part of the Gat van Kielen. In total an area of about 165 hectare.
The end
of 2013 will mean that most of the polluted river beds in the Dordtse
Biesbosch should be cleansed of the pollution and that the river beds will
begin again to show much healthier signs of life. |