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1 Rivers for the Life of Towns 2007
RiverRiver
RestorationRestorationinin
Urban AreasUrban Areas
Petra
Podraza
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2 Rivers for the Life of Towns 2007
Main Problems in Urban Rivers
water quality
discharge volume (floods and peak flow condition)
technical constructed river bed
poor optical appearance
low ecological quality
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3 Rivers for the Life of Towns 2007
Actually measures in urban areas are oftensectoral, considering only one purpose like
Flood protection City development
Natural protection
Recreation
=> Realized measures often are in conflict with other
purposes
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4/224 Rivers for the Life of Towns 2007
Example: Flood Protection
Small flood and rain waterretention basin in the city of
Dortmund
Advantage: technical building preventing
the houses downstream from
flooding lake as a water element in the
cityDisadvantage:
reduced water storing capacity
lake isnt accessible (fenced to prevent children to fall into)
due to dikes, the lake isnt visible
interrupted continuum of the river
midge mass development
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Characteristics of Urban River
Water
Management
Urban
Development
Ecology
Targets+Dem
ands
Targets
+Dem
ands
Targets+Dem
ands
Planning Process
RestrictionsSpatial Limitation, Cost Benefit, Third Party Claim
Measures + Realization
Clearance +Consulting
Concept of Urban River Planing
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6/226 Rivers for the Life of Towns 2007
Example: Flood Protection
Flood andrain water
retention
basin in thecity of
Essen
Water retentionduring rainfall
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7/227 Rivers for the Life of Towns 2007
Example: Impact - Flooding
Best Practice in large rivers
=> Measures in the river basin: activated floodplains
reservoirs
flood retention basin
=> Local in the city dams, dikes and floodwalls
high flow rescue concepts
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Example: Impact - Flooding
Best Practice in small rivers
=> Measures to reduce rainwater discharge
=> Measures in the river
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9/229 Rivers for the Life of Towns 2007
Measures to reduce rainwater dischargeExample: Hoppegarten
Small brook as receiving water=> Large retention volume would
be necessary
Business Park: 100 ha
Rainwater discharge up to 10 m/s
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Measures to reduce rainwater discharge=> Infiltration Trough and Drainage System
Advantage:
Purification of the rainwater
No artificial peak flow condition in the brook
Groundwater recharge
Visual integration in the business park
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Measures to reduce rainwater dischargeINNODRAIN
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Measures in the River
=> rehabilitating urban rivers by combining thedemands of the citizens:
- appropriate structures of stream bed and riparian zone
- continuity of the river
- liveable water quality and hydrology
- nice urban scenery, recreation
- liveable urban climate
- discharging comfort (rain water management)
with
the ecological demands of the aquatic fauna and flora
(=> EG WFD):
- safeness (flood protection)
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13 Rivers for the Life of Towns 2007
But:
spatial limitations inhibit rivers to be restored to
natural conditions
the knowledge on morphological minimum
requirements of the aquatic community to reach GES
or GEP is rather poor.
Designing structures which are able to replace naturalmorphological conditions can help to improve the
aquatic environment with its biological communities.
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14 Rivers for the Life of Towns 2007
Signal forswarming
Shading
Leaf litter
input
Compensatoryupstream flightSummer habitat
for insect adults
Hibernation
Hatching,
Emergence
Eggdeposition
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15 Rivers for the Life of Towns 2007
Man-made structures
replacing natural
morphological conditions:
Mini-floodplain
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16 Rivers for the Life of Towns 2007
Cross-sectiom
Top-view
Signal for swarming
Shading
Leaf litter
input
Compensatory
upstream flight
Summer habitat
for insect adults
Hibernation
Hatching,
Emergence
Egg deposition
Man-made structures replacing
natural morphological conditions:
Bow-constructions at urban riverswith spatial limitation
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17 Rivers for the Life of Towns 2007
Rehabilitated urban river
Social aspects:
Sculpture
Optical impression
Access to the river granted
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18 Rivers for the Life of Towns 2007
Rehabilitated urban river
Social aspects:
Parking place instead of
pedestrian zone with view
points
Access to the river without
plattform, dangerous inflood situations
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19 Rivers for the Life of Towns 2007
Rehabilitated urban river
Ecological aspects:
Gravel banks at the base of
the walls replacing the
amphibian zone
Maximum profile
Stream bed with natural
substrates
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20 Rivers for the Life of Towns 2007
Rehabilitated urban river
Ecological aspects:Sealed wall instead of
natural stone wall with
cavities, covered with twinerand clamberers
Wrong substrate composition,
not complying with the streamtype
No trees to shade =>
eutrophication, substrates
overgrown with water plants
and algae
Wrong plant species on thebanks
Conclusion: The picture looks rather nice,
but the rehabilitated river is not really visible
for the citizen
and
the river does not work as pretentious
aquatic habitat
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21 Rivers for the Life of Towns 2007
Man-made
structuresreplacing
natural
morphologicalconditions
???
No!
It is not so easy to restore urbanrivers appropriately . You have to
consider the human demandsbut you also have to learn to
look at your measures with the
eyes of a fish or an aquatic
insect!
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22 Rivers for the Life of Towns 2007
RiverRiverRestorationRestoration
inin
Urban AreasUrban Areas
Thank you
for your
attention!