Geoscience Reference
In-Depth Information
were categorized into eight groups based on location in the metropolitan region
(core, suburban, fringe, retirement communities), median income (high, middle,
low), and ethnic mix (predominately white/Anglo or minority). Five neighborhoods,
defined by census block groups, were then selected from each of these groups
(n
¼
40) to represent varied socioeconomic and geographic conditions across the
region. For each sampled neighborhood, the survey obtained approximately 20
individual responses. Sampled households were given the option to complete the
survey online, on the phone, or in-person, and either in English or Spanish. With a
final response rate of 51% (n
¼
808), 73% of respondents were White and 19%
were Latino, and 56% of survey respondents were female (Harlan et al.
2007
).
About two-thirds of the survey respondents had at least some college education, and
the median household income for PASS participants was approximately $60,000.
Sixteen PASS neighborhoods reside within the boundaries of Phoenix proper,
while the remaining neighborhoods are located in surrounding municipalities.
Our analysis herein focuses on the Phoenix neighborhoods for which we also
have metered water demand data (n
322 households in 16 neighborhoods). The
analysis employed the following question from the survey to measure residents'
perceptions of personal water use: How much water do you think your household
uses compared to other similar households in the Valley? Residents responded on a
five-point ordinal scale: (1) “much less water,” (2) “a little less water,” (3) “about
the same amount of water,” (4) “a little more water,” (5) “much more water.” With
316 valid responses to this question (excluding “don't know” and 'refuse to answer'
responses), our integrated assessment examines individual- and neighborhood-level
perceptions in relation to local, aggregate demand.
To protect the privacy of individual water customers, the City of Phoenix
provided us with annual water-consumption data (in 100 cubic feet, or
CCF
)at
the census block group (CBG) level. Representing neighborhood demand, the
metered water-use data analyzed in this study is the total for single-family
residences (SFR) in 2005, which closely matches the temporal scale of the 2006
survey data. For each of the 998 neighborhoods, or census block groups, we calculated
the average gallons per capita daily (
GPCD
) from the City of Phoenix water records.
Using Eq. (
2.1
), we estimated the average per capita consumption rate.
¼
CCF
a
748
GPCD
a
¼
(2.1)
n
HH
a
365
Where
GPCD
is the estimated Gallons Per Capita Daily for each census block
group
a, CCF
is the total annual household water use in 100 cubic feet,
n
is the total
number of metered households obtained from the City of Phoenix, and
HH
is the
average household size based on the US 2000 Census. Metered demand values
(in GPDC) for each neighborhood were analyzed in relation to both individual- and
neighborhood-level perceptions based on the demand rates for the census block
group in which survey respondents were located. Some residents in our study area
received water from the Salt River Project (SRP) through a flood irrigation system
that is separate from metered water use. Those properties that receive SRP flood
