Geoscience Reference
In-Depth Information
Table 2.3 Typology of neighborhood water demand and determinants
SRP flood
irrigation
65 Low Low 68 years 40-60 k 10 1 Y
79 Low Low 12 years 40-60 k 54 2 N
94 Low Low 31 years 40-60 k 53 4 Y
99 Low Low 49 years 20-40 k 14 6 N
92 Low Average 9 years 20-40 k 93 3 Y
96 Low Average 8 years 40-60 k 75 5 Y
116 Average Low 61 years 20-40 k 19 8 Y
117 Average Low 56 years 40-60 k 37 9 Y
177 Average Low 15 years
>
$80 k 13 11 Y
101 Average Average 43 years 20-40 k 83 7 Y
133 Average Average 39 years 20-40 k 85 10 N
183 Average Average 14 years 40-60 k 25 12 N
272 High Low 62 years 20-40 k 32 14 Y
324 High Low 40 years
>
$80 k 27 15 Y
237 High Average 39 years 40-60 k 40 13 Y
353 High Average 14 years
>
$80k 11 16 N
Notes:
Gray-shading
highlights the neighborhoods where preceptions do not match water demand
rates. As for data sources, metered water use for 2005 was obtained from the City of Phoenix;
perceived water use from the 2006 Phoenix Area Social Survey (
PASS
); income data from the
2000 Census; mean age of homes from 2007 parcel data indicating the year of construction
(obtained from the Arizona State GIS data repository); flood irrigation data from the Salt River
Project (
SRP
); and finally, the mesic cover variable, which represents the percent of a neighbor-
hood with vegetation cover greater than bare soil, was classified by Stefanov et al. (
2001
) based on
1998 Landsat TM data
Mean age of
homes
% Mesic
cover
GPCD Actual use
Perceived use
Income ($k)
NBHD
(for areas where perceived use was low, rather than average) in relatively old
neighborhoods. Surprisingly, though, these high demand areas have a lower
amount of vegetative cover (30% 'mesic,' or relatively lush landscapes) than
neighborhoods with low (50%) and moderate (44%) demand. This finding may be
due to data limitations, such as the fact that flood irrigation is excluded from the
metered demand data. Yet for our typology neighborhoods, access to flood irriga-
tion does not clearly correspond to relatively low demand rates (Table
2.3
), and
overall, our findings suggest that factors other than groundcover are more critical
determinants of water use.
While percent grass cover does not appear linked to neighborhood water demand
rates, an interesting pattern emerged when we examined the average amount of
green vegetation in areas that cognitively over- and under-estimated consumption
rates (Table
2.3
). First, those neighborhoods that overestimated demand had far
more green vegetation (84%) than both those that underestimated demand (26%)
and those that most accurately estimated demand (46%). This pattern suggests that
neighborhoods dominated by less lush landscapes with fewer lawns— for example,
with desert-like rock groundcover and drought-tolerant plants such as cactus might
falsely perceive local water use to be low when, in fact, pools, irrigation practices,
indoor appliances, or other factors lead to increased consumption rates. Thus,
conservation efforts should focus not only on converting lawns and lush residential
