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Land use connections to demand management
Heejun ChangDepartment of GeographyPortland State University
April 9, 2019
Urban Water Demand Roundtable, Phoenix
Objectives
• Identify how land use change is associated with single family residential (SFR) water demand
• Assess landscape and sociodemographic factors affecting SFR water use change at the census block group scale
• Compare aspatial and spatial model performance for explaining the variation in SFR water use
Population growth in the PDX metro area
Source: New Geography
Study area: Portland
Sociodemography
Factors affecting residential water use
Land cover
% vegetation% developed areas
Water use
New areas builtBldg densityProperty value
Building
IncomeEducationEthnic group
New SFR lots developed, 2005-2011
New SFR lots developed per CBG
Change in SFR water use, 2005-2011
Δ Average bldg. Area % Forest Area
Δ in Hispanic pop Δ in Income
Comparison of OLS with spatial regression
y = β0 + Xβ + ε ε = λWε + ξ
ε = random error termλ = autoregressive coefficientW = spatial weight matrixξ = white noise
Xi
Xj
Yi
Yj
ei
ej
Explanatory variable OLS Spatial
Δ Total bldg. Area 1.93* -0.01
Δ Average bldg. Area -2.14** -1.80*
% Forest in 2011 -3.30*** -2.16**
% Low density develop 4.38*** 2.99***
Δ Hispanic population 5.81*** 3.57***
Δ Income -2.38** -0.82
R2 0.21 0.53
*Statistically significant at the 10% level
**Statistically significant at the 5% level
***Statistically significant at the 5% level
Conclusions• Increasing new larger, low density SFR development is
associated with increasing water demand.
• Higher proportion of green space in the neighborhood is negatively related to increasing SFR water demand.
• Change in ethnic group and income further explain the variation of additional SFR water demand.
• Considering spatial dependence improves the power of explaining variations in SFR water demand change.
Acknowledgements
Hossein Parandvash & Emma Brenneman
Queations??? Contact Heejun Chang changh@pdx.edu
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