Environmental Engineering Reference
In-Depth Information
1962
20'
85'
1997
Figure 4.3
Cross-sectional diagram of Little Walnut Creek illustrating erosion over time. Illustration
by Shawn Kavon,
modifi ed from City of Austin 2001b.
erosion control, vegetated walls offer a more pleasing aesthetic and pro-
vide at least a modest amount of riparian habitat. In the most successful
instances, it is diffi cult to recognize that the bank has been stabilized.
The emphasis on fl ood control and armoring is frequently tied to ideas
of economic development and urban improvement; a prosperous city is
one in which the economy can grow on a stable, predictable founda-
tion. This applied to the damming of the Colorado River in the 1930s
and 1940s and continues on a smaller scale with the creeks in the urban
core. A contemporary example of coupling water control with business
development is the Waller Creek Tunnel Project, slated for completion in
2014. The creek was channelized in the 1970s to control fl ooding in the
eastern part of downtown Austin and in the last decade, new designs for
a stormwater diversion tunnel were proposed along with a master plan.
Nearly a mile long and twenty-two to twenty-six feet in diameter, the $127
million tunnel will accommodate the majority of fl ows in the creek, even
during extreme fl ooding events, to protect the surrounding buildings and
streets.
16
A new pumping station will extract water from Lady Bird Lake
and bring it to the top of the channel where it will be released to provide
a constant surface fl ow reminiscent of a bubbling brook. The project will
create an amenity for downtown businesses to attract tourists and shop-
pers, and is frequently compared to San Antonio's successful Riverwalk
development.
17
Flood control projects such as the Waller Creek tunnel demonstrate
the continued embrace of the Promethean approach to controlling nature
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