The “Integrated River Engineering Project for the Danube East
of Vienna” and its effects on the ecology of the river-floodplain system
Mathias Jungwirth
University of Natural Resources & Applied Life Sciences, Vienna, Austria
The Danube east of Vienna, besides the famous Wachau valley, remains one of the two last freeflowing Danube stretches left in Austria. Following the cancellation of the hard-fought power
plant project at Hainburg in 1984, plans for the foundation of a “Danube Floodplain National
Park” (DFNP) were developed. These were finally realized in 1997. The section of the Danube east
of Vienna is currently characterized by constant bed erosion of approx. 2 – 3.5 cm per year. Since
the 1950s, the average river bed degradation has amounted to 0.7 to 1 m. This negatively impacts
both water resources management and the ecology of the overall alluvial river floodplain system.
Moreover, inadequate conditions prevail for navigation, especially at low flow conditions, requiring urgent action for this area.
The “Integrated River Engineering Project for the Danube East of Vienna” (IREP) was developed
to solve these problems by river engineering measures for the Danube section between the
“Freudenau” hydro-power plant in Vienna (at river km 1921) and the Austrian/Slovakian border
(km 1872.70). Preserving the nature of the free-flowing Danube as a core task, the main objectives
of the IREP are: (1) sustainably improving the fairway, (2) preventing further progression of the
Danube bed incision; (3) maintaining and sustainably improving ecological conditions, especially
in the bank zones and side arms, focusing on the requirements of the DFNP.
In order to achieve these objectives, an interdisciplinary team developed the plan for a highly
complex combination of various river engineering and ecological measures. The key measure to
counteract the strong bed erosion of recent decades is the “granulometric bed improvement”. In
accordance with the so-called “adaptive construction procedure”, coarse gravel will be deposited
over the surface of riverbed zones exposed to erosion, reducing the bed load transport (currently
about 300,000 m3/yr) to about 30,000 to 40,000 m3/yr in the future.
The foundation for all these ecosystem maintenance and sustainable improvement plans is an
interdisciplinarily developed “Leitbild”/target view, which considers the type-specific hydro-morphological conditions and biocoenosis of the former river-floodplain system. In the frame of that
Leitbild-development and the subsequent planning process, also potential conflicts regarding the
different goals and approaches between the EU-Water Framework-Directive and Natura 2000/FFHDirective were discussed and practical solutions found. The realization of all the plans and measures for the different components of the alluvial river-floodplain system will be accompanied by
comprehensive pre-and post-monitoring surveys. For regular evaluation and control, an advisory
board of independent scientists was established at the onset of the project. One important task of
the planning team was to present the new approaches to the public by comprehensive participa-
1
tion processes. Additionally, in cooperation with the International Commission for the Protection
of the Danube River (ICPDR), this new planning and management philosophy was incorporated
into the “Joint Statement on Guiding Principles for the Development of Inland Navigation and Environmental Protection in the Danube River Basin”, which has been signed by all Danube countries,
the Danube Commission and the International Sava River Basin Commission.
2
PowerPoint
Biodiversity of surface waters, floodplains and groundwater
29th/30th October, Bonn
The "Integrated River Engineering Project for
the Danube East of Vienna“ and its effects on
the ecology of the river-floodplain system
Mathias Jungwirth
Content
• History: the „Hainburg era“ and the National Park
• actual problems & deficits in the alluvial river - floodplain system
• the „Integrated River Engineering Project for the Danube East of Vienna„
- planning team
- Leitbild/ „target view“
- the “granulometric bed improvement” concept
- measures in the river and floodplain / adaptive management
• pre- and postmonitoring / EU-WFD / Natura 2000 / FFHD
• WWF / ICPDR / Joint statement on Inland Water Navigation
• conclusions
3
Danube
east
of
Vienna
3
1980: plans to realize the hydropower plant Hainburg became concrete
1984: in late autumn clear-cutting of floodplain forest was followed by heavy protests and
occupation of the area designed for the power plant
1984: peace was made up by the Austrian Chancellor at Christmas
1996: the Republik of Austria and the provinces of Vienna and Lower Austria signed a
contract to establish the „Nationalpark Donau-Auen“
History
4
Flood protection & navigation:
straightened river, groynes, rip rap ….
loss of in-stream structures, decreased connectivity….
Current problems & deficits
hydro-electric power plants along the Austrian Danube
Current problems & deficits
5
The crucial problem: river bed degradation
Decoupled river-floodplain system
aggradation during floods
river bed degradation
Current problems & deficits
142,25
trend of river bed
degradation
m. a. sl.
142,00
141,75
141,50
141,25
141,00
1970 – depth of ground water table
140,75
1950
1960
1970
1980
1990
2000
1996
2020
Current problems
& deficits
6
Several EU Life projects were realized in the past, but……
due to ongoing river bed degradation
decoupling of the river from
the floodplains took place
Current problems & deficits
Ongoing river bed degradation will affect
•
•
•
•
•
groundwater & flooding
connectivity
sidearms and other floodplain
waters regarding flow &
sedimentation
the overall environment &
habitats
species / biodiversity,
etc.
Bild: Nationalpark Donau-Auen
Current problems & deficits
7
Navigation
Problems:
fairway
depths
low flow
predictability
maintenance costs
Goals:
improvement of fairway conditions
reduction of maintenance costs
current problems & deficits
Summarizing the current ecological problems and deficits in
the alluvial river-floodplain system:
-stabilized (channelized) river (flood protection & navigation)
-increased bed load output
-reduced bed-load input and transport from upper catchment
-river bed degradation 2-2,5 cm per year (up to 1m in 50 years)
-sinking ground water table
-sedimentation within flood plain
-decoupling of river and floodplains / connectivity
-consequences for biota
Need for action!
Current problems & deficits
8
Integrated River Engineering Project
for the Danube East of Vienna
Project area: km 1.921,0 to km 1.872,7 - about 48 km length- stretching from
the hydroelectric power plant Freudenau to the Austrian-Slovakian border
Integrated River Engineering Project
integrative planning
Federal Ministry for
Transport, Innovation
and Technology
(BMVIT)
via donau
Planning team
Steering comitee
Independent experts for
Water Engineering,
Navigation, Ecology,
Landscape Planning…
Representatives of
BMVIT & National Park
interdisciplinary team
(Water Engineering,
Navigation, Ecology,
Landscape Planning and
regional development)
Participation
Public workshops with:
ministeries, public
authorities, communities,
NGOs, representatives of
navigation & National Park
...
Integrated River Engineering Project
9
Ecology and navigation: two different „Leitbilder“
(need for harmonization)
1805
navigation:
improve fairway as much as possible!
Bild: Nationalpark Donau-Auen
ecology / nature protection/ National Park:
decrease stabilization as much as possible!
Bild: via donau
both goals had to be secured (on the basis of different legislations)
Leitbild / „target view“
Quelle: Jungwirth (2006)
multi-dimensional nature of riverine landscapes
Ward & Stanford 1995
Leitbild / „target view“
10
type-specific Leitbild
highly dynamic alluvial system
braiding channel network
complex connectivity conditions
balance of sedimentation/erosion
shifting habitat mosaic
high biodiversity…..
Leitbild / „target view“
Leitbild / „target view“
11
Habitat composition of the Danube – River Landscape (Machland)
Percentage of 10-year flood area (%)
natural
channelisation period
post-channel.
35
natural state:
high turnover, but
relative „stable“
habitat compos..
(shifting-mosaic
steady-state)
30
25
20
15
10
5
0
1715
1775
1812
1817
1821
1829
1832
1835
1838
1859
1925
total water bodies
Parapotamon A
Tributaries
Eupotamon A
Parapotamon B
VABB
Eupotamon B
Plesio-/Palaeopotamon
1991
Post- channeliz.
state: One-sided
development.
(static-state)
19
Leitbild / „target view“
Set of ecological measures postulated by the National Park
bridges / openings
removal of barriers
reconnecting sidearms
measures
12
Navigation / improvement of the fairway
adaptions of the fairway mainly are related to widths and water depths
navigation needs
RNW
dredged material
is re-deposited in
deeper or lateral
parts of the
channel
elevation of the
low water table
dredging off obstacles within the main fairway
increased depth of fairway instead of deepening the channel
mainly will be reached by elevating the water table
measures
Integrated River Engineering Project / granulometric bed improvement
ZUSTAND I
ZUGABEMATERIAL Z40/70
dm ≈ 52 mm
100
dm ≈ 26 mm
Normalgeschiebe
80
Siebdurchgang in Gew.%
ca. 25 cm
90
70
60
50
40
Zugabematerial
Ø40/70mm
30
20
10
0
0
30
60
90
120
150
180
Korndurchmesser [mm]
measures
22
13
Integrated River Engineering Project / granulometric bed improvement
ZUSTAND II
dm ≈ 39 mm
MISCHUNG A+Z40/70 (ca. 450 kg/m2)
100
90
Normalgeschiebe
~50 cm
Siebdurchgang in Gew.%
80
70
60
50
Mischungsbereich
40
30
20
Zugabematerial
Ø40/70mm
10
0
0
30
60
90
120
150
180
Korndurchmesser [mm]
measures
23
Integrated River Engineering Project / granulometric bed improvement
Foto: Austrian Hydro Power, Dipl.Ing. Schimpf
measures
14
Integrated River Engineering Project / granulometric bed improvement
placement of a coarse gravel
layer (40 / 70 mm)
average grain-diameter:
currently 25 mm
after mixing → 40 … 55 mm
volume: approx. 2,2 Mio m3
capacity of bed load transport:
300.000 … 400.000 m³/a
→ 30.000 … 50.000 m³/a
granulometric bed improvement was
(1) calculated / modelled
(2) tested in a hydraulic lab
(3) currently tested in situ
measures
Integrated River Engineering Project / granulometric bed improvement
goals: increased river bed stability and elevated water level
R N W - W ILD U N GS M A U E R [m ü.A .]
RNW -VERÄNDERUNGEN: W ILDUNGSMAUER
142,00
141,90
141,84
141,80
compensation of erosion &
141,74
141,70
degradation of the river bed
141,64
141,60
141,54
141,50
during the last 10 to 20 years
141,40
141,30
141,20
141,21
Dat enquelle: KWD ( "Kennzeic hnende Wasser st ände der
Donau") , WSD; mit Eint r agung eines
141,10
141,07
Unsicher heit sber eiches v on +/ - 10 cm
141,00
1950
1960
1970
1980
1990
2000
2010
2020
RNW ⇔ RNQ=Q(94%)
Wasserspiegel-Änderungen: RNW
measures
26
15
Integrated River Engineering Project
granulometric bed improvement takes place in an adaptive process
placement of a coarse gravel-layer (40 / 70 mm) will be
restricted to erosive areas and ca 50% of the channel width
adaptive means: no coarse gravel-layer at riffles and other parts tending to aggradation
measures
27
Integrated River Engineering Project: volumes of bed material moved
coarse material (40/70 mm):
ca. 2,2 Mio. m3
INPUT
Danube material (dredging / re-depositing):
ca. 470.000 m3
REALLOCATION
project area
Rip-rap material:
ca. 400.000 m3
OUTPUT (excess material)
measures
16
Foto: Nationalpark Donau-Auen
enlarging cross profiles improves flood protection
and the environment
Uferrückbau
Bild: Nationalpark Donau-Auen
measures
Re-connecting the river and ist floodplains
sedimentation during floods
disconnected sidearms &
backwaters
fragmentation by flood protection
measures
River bed degradation
Nebenarme:
Problemstellung
measures
30
17
Re-connecting the river and ist floodplains
side arm opening
reopening & flushing
removal of flood protection measures,
roads etc.
elevating the
Danube water
level
Nebenarme:
Maßnahmen
measures
31
Re-connecting the river and ist floodplains
NEBENARMBEAUFSCHLAGUNG, SPITTELAUER ARM: 1992 (exempl.)
Q- Spittelauer Arm [m3/s]
derzeitiger Zustand
mit Gew ässervernetzung
800
800
700
700
600
600
500
500
400
400
300
300
200
200
100
100
0
0
"1992" Sim ulations re chnung
measures
32
18
Re-connecting the river and ist floodplains & restoring in-stream structures
currently 100% of the shore line stabilized ( closed rip rap at both shore lines)
gravel bank
Destabilization measures increase
structures/habitats within the low flow
channel and along the shorelines
rip rap removal
steep bank
restoration measures will take place
along 50 % of the shore line
measures
33
Improving the river channel´s set of in-stream structures
Pilotprojekt Witzelsdorf 2007/2008
measures
... Buhnenumbau ...
34
19
Restoration measures: overview
measures
35
pre- and postmonitoring / EU-WFD / Natura 2000 / FFHD
alluvial river floodplain system since 1996 is a National Park
regular scientific research & monitoring
comprehensive and detailed data / information available regarding
environment and biota
several EU-LIFE restoration projects in the frame of Natura 2000 with
comprehensive pre- and post-monitoring data
for the „report of the environmental impact assessment“ of the IREP
many further data collected (habitats, vegetation, birds, mammals,
amphibians, fish, insects….)
intensiv discussions regarding EU-WFD / Natura 2000 / FFHD
good data basis and team allowed solutions of potential conflicts
also in future pre- and postmonitoring for detailed projects in the
frame of IREP foreseen
EU-WFD / FFHD, monitoring
20
terrestrial / semiterrestrial vegetation
Josephinische Landesaufnahme
(1764-1787)
actual
vegetation
prognosis
for 100
years
ahead
without
project
EU-WFD / Natura 2000 / FFHD / monitoring
pionieer vegetation
increased dynamic processes & connectivity by river bed widening,
removing stabilization measures and re-opening of sidearms
rejuvenation
instead of
stable situations
Schwarzstorch
EU-WFD / Natura 2000 / FFHD / monitoring
21
terrestrial/semiterrestrial habitats & biota
increasing dynamic processes & connectivity by river bed widening,
removing stabilization measures and re-opening of sidearms
Key factors of hydro-morphological dynamics:
erosion, sedimentation & turnover of material
leading to typical fluvial habitats
Eisvogel
Laufkäfer
Flussregenpfeifer
Flussuferläufer
EU-WFD / Natura 2000 / FFHD / monitoring
winter quarters for aquatic birds
• refugial zones, back waters, islands
• gravel bars with smooth gradients,
• shallow water areas for feeding and
resting
Schellente
Zwergsäger
Gänsesäger
EU-WFD / Natura 2000 / FFHD / monitoring
22
predator birds
• generaly improved environment
• enhanced food resources by increased and improved aquatic habitat
Schwarzmilan
Schwarzstorch
Seeadler
EU-WFD / Natura 2000 /
FFHD / monitoring
fish communities
rheophilic guild
lotic main stem channel habitat
EU-WFD / Natura 2000 / FFHD / monitoring
23
fish communities
stagnophilic guild
lenitic „old arms“/ oxbows
EU-WFD / Natura 2000 / FFHD / monitoring
WWF / ICPDR / Joint statement on Inland Water Navigation..
2006: critical comments of WWF that the IREP will enforce further
channelization projects for navigation, in particular in the lower Danube
Steering committee asked ICPDR to transfer the new „planning philosophy“
of the the IREP to all other Danube member states
2007: ICPDR organized 3 workshops followed by the publication of the
„Joint Statement on Guiding Principles for the Development of Inland
Navigation and Environmental Protection in the Danube River Basin“
Signed by the ICPDR, the „Danube Commission“ & the „Sava Commission“
Joint statement
24
Summary (1)
lessons learned
Inter- and trans-disciplinary must be realized and „lived“
Information & partizipation important tasks
Type-specific Leitbild approach crucial issue (define deficits,
traceability, transparency…)
EU-WFD important (process orientation, good ecological status…)
Natura 2000 / FFH Directive no contradiction; harmonization needed
Pre- and postmonitoring essential for sound evaluation
Better evaluation methods (instruments) for floodplain environment needed
Adaptive management important, allowing project to be improved
conclusions
Summary (2) „paradigms“ developed and questions still to be answered
Minimize water engineering measures
Initiate & maximize natural processes
Learn to work with „smooth“ structures,
as typical elements of natural hydro-morphology
Thank You !
Problems still valid:
how to predict & control measures in large fluvial systems
how to get agreement & sufficient space for „trial & error“
how to realize step by step approches by an adaptive
management for to fulfill „learning by doing“
Conclusio
46
25