Background - Climate Change and Infrastructure, Urban Systems, and Vulnerabilities - page 10

BOX 1
Wallow Fire Threat to the Springerville, AZ,
Electric Power Generating Station

One threat to built urban infrastructures is in-
creased exposure of critical assets or nodes to
wildfires in areas forecast to receive lowered pre-
cipitation. An illustration of what these impacts
might look like occurred in June 2011, when a ma-
jor wildfire threatened the Springerville Generat-
ing Station. This station provides critical power
into the Tucson Electric Power Company, the Salt
River Project, and Tri State Generation and Trans-
mission. As part of emergency response, the cas-
cading impacts of the station's loss were modeled
as the event unfolded. Consequence and forecast
models tracked the wildfire threat and estimated
the effects on the Arizona power grid if this gener-
ating station were to be taken off line.

Analysis indicated that there was enough
power supply reserve in the grid to avoid a black-
out in Tucson, but the modeled case illustrated
one kind of vulnerability of an infrastructure to
a weather-related extreme event that could cas-
cade in a similar manner. On September 9, 2011, a
transmission line near Yuma, AZ, tripped out due
to high temperatures, starting a chain of events
that led to shuting down the San Onofre nuclear
power plant; and power was lost to the entire San
Diego County power distribution system, serving
approximately 7 million power customers. Power
was out for 12 hours resulting in sewage releases
and disruptions to city water distribution (see text
below).

Government

Chemical
Industry

Agriculture

Figure 2 An illustration of
infrastructure interdependencies

Government
Regulation

Water

Economic
Prod.

Defense Ind.
Base

Food

Key
Resources

Postal/
Shipping
Transportation

Banking/
Finance

Emergency
Services

Fuel

Electric Power

Public Health

Government
Services

Telecomm.