Subhrajit Guhathakurta

The Impact of the Phoenix Urban Heat Island on Residential Water Use

Abstract One goal of the smart growth movement is a more compact urban form, intended to reduce energy use and the cost of moving materials, products, and people. The benefits of compactness are compromised, however, if higher densities and more intense land use create urban heat islands, which increase water and energy use. This study examines the effects of Phoenixs urban heat island on water use by single-family residences, controlling for relevant population and housing attributes. Our statistical analysis demonstrates that increasing daily low temperatures by 1° Fahrenheit is associated with an average monthly increase in water use of 290 gallons for a typical single-family unit. These results suggest that planners should consider effects on water demand as well as other environmental consequences when they evaluate growth strategies, and use incentives to encourage efficiency and sustainability.

Spatial and Temporal Capitalization Effects of Light Rail in Phoenix From Conception, Planning, and Construction to Operation

Studies have shown that proximity to light rail transit (LRT) stations positively affects property values and that these effects can appear before a system opens for operation. Here, we expand on these questions. We explore capitalization effects at several stages during the planning process for four real estate markets: single-family homes, homes in multifamily structures, commercial properties, and vacant land, using the case study of the LRT system in Phoenix, Arizona. We confirm earlier results concerning the value of proximity, and also find that markets exhibit value increases at different stages during the planning and construction process.

Residential Land Use, the Urban Heat Island, and Water Use in Phoenix: A Path Analysis

While previous studies have shown that urban heat islands (UHI) tend to increase residential water use, they have not yet analyzed the feedbacks among vegetation intensity, diurnal temperature variation, water use, and characteristics of the built environment. This study examines these feedback relationships with the help of a path model applied to spatially disaggregated data from Phoenix, Arizona. The empirical evidence from the observations in Phoenix suggests the following: (1) impervious surfaces contribute to increased residential water use by exacerbating UHI; (2) larger lots containing pools and mesic vegetation increase water demand by reducing diurnal temperature difference; and (3) smart design of urban environments needs to go beyond simplistic water body- and vegetation-based solutions for mitigating uncomfortably high temperatures and consider interactions between surface materials, land use, UHI, and water use.

The Impact of Subregional Variations in Urban Sprawl on the Prevalence of Obesity and Related Morbidity

This article examines the relationship between urban sprawl and health using a new methodological approach that accounts for the subregional variation in the different attributes of sprawl in metropolitan regions. We have developed several indicators of sprawl at the neighborhood level, including compactness, land use mix, automobile dependency, transportation connectivity, and walkability. We then use multinomial logistic models to estimate the contribution of these characteristics to the formation of high- and low-disease-prevalence clusters. Results indicate the significant role of walkability, percentage open space, and commute burden in explaining the prevalence of obesity and related diseases.

A watershed at a watershed: the potential for environmentally sensitive area protection in the upper San Pedro Drainage Basin (Mexico and USA)

The watershed is advocated as an appropriate unit for ecological planning. Watersheds, or river drainage basins, can be understood through an ecological chorography. The upper San Pedro River basin of southern Arizona (USA) and northern Sonora (Mexico) is used as an example. This watershed is currently facing significant growth pressures. Rapid urbanization, cattle ranching, and irrigated agricultural pumping in the drainage basin are having negative environmental consequences, including water quality and supply problems, increased soil erosion, threats to wildlife habitats, and degradation of scenic resources. Copper mining, just outside the watershed, potentially impacts groundwater and the San Pedro riparian system. The protection of environmentally sensitive areas would help to maintain the biological integrity of the region. This paper focuses on the design of a framework for the identification of environmentally sensitive areas in the watershed and an analysis of existing government plans to protect such areas. The proposed framework can coordinate local, state, and federal efforts to achieve their protection objectives.

Functional Unit, Technological Dynamics, and Scaling Properties for the Life Cycle Energy of Residences

Prior LCA studies take the operational phase to include all energy use within a residence, implying a functional unit of all household activities, but then exclude related supply chains such as production of food, appliances, and household chemicals. We argue that bounding the functional unit to provision of a climate controlled space better focuses the LCA on the building, rather than activities that occur within a building. The second issue explored in this article is how technological change in the operational phase affects life cycle energy. Heating and cooling equipment is replaced at least several times over the lifetime of a residence; improved efficiency of newer equipment affects life cycle energy use. The third objective is to construct parametric models to describe LCA results for a family of related products. We explore these three issues through a case study of energy use of residences: one-story and two-story detached homes, 1,500-3,500 square feet in area, located in Phoenix, Arizona, built in 2002 and retired in 2051. With a restricted functional unit and accounting for technological progress, approximately 30% of a buildings life cycle energy can be attributed to materials and construction, compared to 0.4-11% in previous studies.

Simulating the effect of light rail on urban growth in Phoenix: An application of the UrbanSim modeling environment

This study uses a comprehensive urban simulation model called UrbanSim to evaluate the viability and suitability of a light rail system for the Phoenix metropolitan area. The impact of the proposed light rail system is examined by observing the changes in the number and types of households adjacent to the proposed transit line in 2015. A scenario that includes light rail is compared with a scenario in which light rail transit is not introduced. Although the results confirm the expectation that most areas adjacent to light-rail stations would increase in household density, there was a surprising decline in household density in other areas, especially in the corridor next to Arizona State University. This area already has an extremely high population density, with housing that is mostly rental and aimed at students and other low- to mid-market clients. It is suggested that the light rail transit would provide an amenity that would push this area towards gentrification and push out the current population.

Urban Modeling and Contemporary Planning Theory: Is There a Common Ground?

This article provides a critical review of the history of urban modeling in North America, with a focus on unraveling some fundamental issues that militated against incorporating the first-generation urban models into planning practice. After examining the underlying theoretical context in social practice, I demonstrate that the re-emergence of a different form of rationality creates the conditions for incorporating new forms of urban models. Finally, I highlight the developments in group decision support systems research and suggest how these systems, together with a geographic information systems component, can be designed for critical planning practice.

What is Driving the Growth of New “Sunbelt” Metropolises? Quality of Life and Urban Regimes in Greater Phoenix and Brisbane-South East Queensland Region

Abstract In this paper we explore the conditions leading to the evolution and eventual weakening of urban regimes by comparing two sunbelt metropolitan areas in two continents. While Greater Phoenix is selected to represent the US case, the Brisbane-South East Queensland region provides a similar representative case in Australia. Both Greater Phoenix and Brisbane-SEQ have been the top or close to the top performers in population growth and economic growth compared to other metropolitan regions in their respective countries. In both cases coalitions of development interests and public officials created conditions for increasing rates of population growth and expansion of metropolitan territories. As growth pressures mounted over time leading to a deterioration of quality of life, local politics began to revolve around local issues of congestion, pollution, and better urban services. This paper explores the changing nature of urban growth coalitions and discusses their implications for the respective metropolitan futures.

Environmental Equity in Central Cities: Socioeconomic Dimensions and Planning Strategies

This study presents the case of a neighborhood in South Phoenix, Arizona, where latent feelings of inequity in the community were heightened by a serious contamination incident. The incident amplified perceptions of environmental risk and reinforced perceptions of distributional, procedural, and process inequities. Housing prices within the affected area continue to reflect a risk-induced discount when compared to those in adjacent and similar neighborhoods. The property value diminution in the affected area has occurred despite assurances of governmental agencies that residual contaminants are within safe limits. The article concludes with a number of strategies for planners, which should help strengthen planning processes that involve environmental equity considerations in the central areas of our major cities.