Environmental Engineering Reference
In-Depth Information
2.2.3 Potential Con
icts Between Goals of WFD
and Natura 2000
fl
However, the objectives of the WFD on the one hand and the Habitats and birds
directives on the other hand may also evoke opposing effects, especially if water
dependent Natura 2000 sites with secondary biotopes or species of cultural land-
scapes are concerned (Fuchs et al. 2010 , p. 113 et seq.; Wirth et al. 2000 seq): The
WFD concept of reference conditions is based on existing natural or near-natural
river reaches. If such examples are missing at present, historical information
where available
or modelling approaches can be applied to reconstruct historical
conditions. If neither of these ways can be followed successfully, expert judgement
is requested to de
ne reference conditions. The requirements of HD relate to the
present and not to any historical conditions of the relevant habitats. This difference
can lead to con
ict of interest.
In aquatic systems, especially those represented by regulated rivers and their
fl
fl
floodplain water bodies, e.g., cut-off side channels and oxbows, WFD calls for re-
establishing the historical situation, which was characterised by permanent inter-
connection of most
floodplain waters. Therefore, still water environments, which is
the character of former river bends or loops turned into oxbows by regulation
measures, are not the near natural condition de
fl
ned for high ecological status, and
do certainly not conform with the de
nition of
'
good ecological status
'
, demanding
that:
The values of the biological quality elements for the surface water body type
show low levels of distortion resulting from human activity, but deviate only
slightly from those normally associated with the surface water body type under
undisturbed conditions
. 1.2 table 1.2 WFD). The present condition
of cut-off meanders and river channels deviates more than just
(Annex V N
°
'
slightly
'
from their
'
'
former structure and hydrology, and
ned by WFD
cannot be appointed to these aquatic habitats. In such cases, the conservational
values regarding the HD (and sometimes the BD) compete against a full recla-
mation of river dynamics when strictly implementing WFD aims.
On the other hand, recent studies in the Austrian
good ecological status
de
(by
appointment of IUCN) revealed two diverging situations. Floodplain waters char-
acterised by high connectivity with the main river channel were either free of
aquatic plant growth or showed very low diversity and abundance of these plants. In
contrast, water bodies with moderate to low connectivity with the main river
channel are inhabited by highly valuable aquatic vegetation and its associated
fauna, from invertebrate level to amphibians, birds and mammals, which developed
since river regulation was
'
Danube National Park
'
finalised in the mid-1870s.
floodplain waters the situation of aquatic plants is comparable
with that of main river courses and active side channels. WFD would require little
or no changes in morphology and/or connectivity conditions, whereas the conser-
vation status may well comply with a
In the
first type of
fl
'
favourable
'
situation.
floodplain waters, which were active side channels in pre-
regulation time, WFD would require action towards considerably intensifying
In the second type of
fl
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