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Ecological
Survey
Evaluation
of Wetlands and Floodplains Areas in the Danube River Basin (WWF
Auen-Institute, Germany for UNDP/GEF)
(see
also article in "River Restoration")
The
study has been undertaken to define priority Wetland and Floodplain
Rehabilitation Sites as a component of the danube Pollution Reduction
Programme. The study was prepared by WWF-Danube-Carparthian-Programme
and the WWF-Auen Institut (WWF-Germany), under the guidance of the
UNDP/GEF team of experts of the Danube Programme Coordination Unit
(DPCU) in Vienna (today ICPDR, International Commission for the
Protection of the Danube Basin). To create an evaluation consistent
throughout the whole area, factors that were available everywhere
had to be chosen. In addition to the data on floodplain size and
type, surface-covering landuse data (CORINE and own classified data)
were also available.
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An
evaluation procedure based on the following factors has therefore
been developed:
- floodplain
type (recent floodplain, outlet section/polder, former floodplain)
- floodplain
width (>5km, 2,5-5km, 1-2,5km and 0-1km)
- land use
data (forest, swamp/waters, meadows, farmland, settlements)
The
evaluation resulted from a classification of the three factors.
The result have been grouped in four classes from a low to a very
high ecological value. 450 sections
have been evaluated. The result has been represented in the map
"Ecological Potential of
Floodplains in the Danube River Basin".
Besides
the ecological value, the nutrient reduction potential had to be
studied as well. It is an uncontested fact, that recent, inundated
floodplains have a positive effect on water quality improvement
and nutrient input reduction if they are not subject to intensive
agricultural use. This is why one may suppose that all areas of
the ecological potential map that have been considered as definitely
quantified at the moment due to insufficient and inhomogeneous available
data. One can argue, however, based upon review of studies and the
general knowledge on all factors influencing the Danube basin, that
a range of values for nutrient reduction can be proposed. They may
be represented as follows:
- kg total
N/ha/year: 100-150
- kg total
P/ha/year: 10-20
The
total area of historical floodplain
wetlands in the area of investigation was 41.605qkm.
The study found that the total area of remaining floodplain wetlands
in the area of investigation was only 7.845qkm. The remarkable
extent of floodplain loss in the study area is therefore
of 81%!
Selected
species were expected to contribute to the estimation of the ecological
value of the investigated floodplains. Extensive investigation in
the Danube catchment area of bioindicator data demonstrated (sample
map White-Tailed Eagle) , that geographically extensive and
current data are not available, or only very limited.
(Reference: DANUBE
POLLUTION REDUCTION PROGRAMME (1999): Evaluation of Wetlands and
floodplain areas in the Danube River Basin. WWF Danube-Carpathian
Programme and WWF-Auen-Institut (WWF-Germany))
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© FLUVIUS, Vienna 2005
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