The Isar River in Germany and the Virgin River in the United States both underwent restoration projects to address issues from human development along their banks. The Isar restoration aims to restore the river's ecology and recreation areas while improving flood control, removing concrete canalizations where possible. The Virgin restoration focused on stabilizing banks and removing invasive plants to improve safety after devastating floods, though it resulted in a more canalized design than the Isar's efforts to reflect the river's natural form. Both projects met goals like improving habitats and water quality, but the Isar restoration maintains a longer-term focus on fully restoring native species.
2. Human Populations
Human populations have
always liked to live on river
banks for as long as we have
had cities.
How do we maintain river
systems while protecting our
populations? This is a problem
that has persisted for as just
as long as cities.
In Europe this has been dealt
with in a fairly traditional
way.
Isar River in München Germany, early wood print and
Roman wood carving showing est. of München
3. Isar River
• The Isar River is one of the most important
tributaries of the Donau (Danube) River in
Europe.
4. Isar River
• It stretches through many towns and
continues on to connect to the Donau
which eventually continues to the
Schwarzes Meer (Black Sea).
5. Isar River
The Cities have grown right up
to the rivers edge through the
length of the river. So for
safety the river has been
changed along the length of
the river.
Isar river 2004 by Denniey Snyder
Isar River by Grzegorz Jereczek
6. Isar River
• Damage from WWII is still being repaired
through Germany as can be seen in these
pictures from the cathedral in Ulm and in
the churches in München.
7. Isar
• Due to lack of time and resources following
the war many rivers, including Isar, were
simply cemented off into artificial "canal”
like systems.
River Isar in Munich near
Deutsches Museum pre 2000 via
enacademics
8. Virgin River
• In the USA many systems similar to their
counterparts in Europe are beginning to
experience similar growing pains to those
experienced 100-200 years ago.
Virgin River Watershed via Shannon wikicommons
How do we protect the
people while allowing them
to live near the rivers?
9. Virgin River
• In 2005 the Virgin River experienced a
flood that caused severe damage to the
area.
12. Virgin River
• What caused this devastation?
− City allowed builders to build in alluvial basin
of the river.
13. Virgin River
− The system was over run with Tamarisk trees,
which are not native but grow very fast, and
Cotton Woods. The trees slow the flow of
water which causes it to back up and flood.
16. Isar and Virgin
Isar River Virgin River
Length 183 miles (295 km) 162 miles (261 km)
Average Discharge 175 m³/sec Highly variable
278 m³/sec during flood
Elevation change 848 m 780 m
Population ≈200,000 ≈165000
Restoration Started 2001 2005
Est. Cost 28 million €
($30.5 million)
$56.8 million* (52.2
million €)
I have been to
Time to complete ≈15 years ≈3 years
Entire river? Yes Only St. George region
*Included damages done to house and properties of at least $35 million
17. Goals
• Isar
− Restore native species
− Restore leisure sites
− Improve water quality
− Restore banks by
removing canal system
where possible
− Restore islands in
stream and breath
− Improve flood control
− Where possible restore
river path
• Virgin
− Find a balance between
natural and designed
river
− Straighten meandering
river within city limits
− Lower river for floodplain
evaluation
− Improve bank structure to
increase stability
− Vegetate with native
species
− Over widen river
− Remove any debris or
exotics plants within river
− Implement appropriate
bioengineering practices
27. Final design goals
Isar implements a restoration of a
gradual bank with a dyke that
drains with high water infiltration
rates positioned back behind the
bank itself.
Virgin lengthens the river and
places geotextile fabric with stones
to stabilize the bank and prevent
plants from growing down into the
river where they could slow the
flow.
29. How do these sum up?
• Isar is a true attempt to be a “river that
reflects its alpine origin.” Within the city it
is a “nature-oriented river landscape… that
presents the metropolitan population a
nature that is intact and attractive… and
also provides a habitat for indigenous river
plants and animals.”
• Virgin is “enhance stability, increase
habitat, and enhance recreation (and)
aesthetics.” In addition “removal of salt
cedar and other exotic vegetation” while
improving native species patterns.
30. Virgin Restoration?
• Virgin restoration secured the safety of the
people but moved the river system to a
design that is like that of the river systems
of the late 1800’s and early 1900’s in
Europe; a canal like safety system.
• Can it be called restoration?
− Restored a structure of terraced systems on the
bank
− Restored housing complexes
− Was extremely successful at removing tamarisk
− Improved river flow by removing all species in
stream
Focused on safety over ecology
31. Isar Restoration
• Restoration on Isar is still an ongoing
process. It was hoped to be completed in
2015 but a flood that occurred in the
construction zone in 2007 slowed the
process. 80% of the restoration work is
done but native species establishment is
ongoing as a coalition of Universities across
Bayern (Bavaria) continue to study old
reports and raise species for transplants.
− River quality- successful
− River bank restoration- successful
− Flood improvement- successful
− Native species restoration- ongoing
− Recreation improvements- successful
33. References
Arzet, K., & Joven , S. (2010). The Isar Experience –Urban River Restoration in Munich. München:
Wasserwirtschaftsamt.
Binder, W. (2006). Case Studies: Isar; Germany. Munich: Bavarian Environment Agency.
Natural Channel Design, Inc. (2007). Final Report Virgin River Master Plan. Flagstaff : Washington County
Water Conservancy District .
Rivers by Design. (2011). Isar River Munich: Pamphlet. Munich: Munich River Alliance.
Snyder, D. J. (2015, March 25). 2005 Flood. (M. D. Snyder, Interviewer)
USGS. (2006). Flooding and streamflow in Utah during water year 2005. Washington D. C.: USDI.
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