Already the leading cause of weather-related deaths in the United States, extreme heat events (EHEs) are expected to occur with greater frequency, duration and intensity over the next century. However, not all populations are affected equally. Risk factors for heat mortality—including age, race, income level, and infrastructure characteristics—often vary by geospatial location. While traditional epidemiological studies sometimes account for social risk factors, they rarely account for intra-urban variability in meteorological characteristics, or for the interaction between social and meteorological risks.

This study aims to develop estimates of EHEs at an intra-urban scale for two major metropolitan areas in the Southwest: Maricopa County (Arizona) and Los Angeles County (California). EHEs are identified at a 1/8-degree (12 km) spatial resolution using an algorithm that detects prolonged periods of abnormally high temperatures. Downscaled temperature projections from three general circulation models (GCMs) are analyzed under three relative concentration pathway (RCP) scenarios. Over the next century, EHEs are found to increase by 340-1800% in Maricopa County, and by 150-840% in Los Angeles County. Frequency of future EHEs is primarily driven by greenhouse gas concentrations, with the greatest number of EHEs occurring under the RCP 8.5 scenario. Intra-urban variation in EHEs is also found to be significant. Within Maricopa County, “high risk” regions exhibit 4.5 times the number of EHE days compared to “low risk” regions; within Los Angeles County, this ratio is 15 to 1.

The project website can be accessed here. 

As average temperatures and occurrences of extreme heat events increase in the Southwest, the water infrastructure that was designed to operate under historical temperature ranges may become increasingly vulnerable to component and operational failures. For each major component along the life cycle of water in an urban water infrastructural system, potential failure events and their semi-quantitative probabilities of occurrence were estimated from interview responses of water industry professionals. These failure events were used to populate event trees to determine the potential pathways to cascading failures in the system. The probabilities of the cascading failure scenarios under future conditions were then calculated and compared to the probabilities of scenarios under current conditions to assess the increased vulnerability of the system. We find that extreme heat events can increase the vulnerability of water systems significantly and that there are ways for water infrastructure managers to proactively mitigate these vulnerabilities before problems occur.

The leading source of weather-related deaths in the United States is heat, and future projections show that the frequency, duration, and intensity of heat events will increase in the Southwest. Presently, there is a dearth of knowledge about how infrastructure may perform during heat waves or could contribute to social vulnerability. To understand how buildings perform in heat and potentially stress people, indoor air temperature changes when air conditioning is inaccessible are modeled for building archetypes in Los Angeles, California, and Phoenix, Arizona, when air conditioning is inaccessible is estimated.

An energy simulation model is used to estimate how quickly indoor air temperature changes when building archetypes are exposed to extreme heat. Building age and geometry (which together determine the building envelope material composition) are found to be the strongest indicators of thermal envelope performance. Older neighborhoods in Los Angeles and Phoenix (often more centrally located in the metropolitan areas) are found to contain the buildings whose interiors warm the fastest, raising particular concern because these regions are also forecast to experience temperature increases. To combat infrastructure vulnerability and provide heat refuge for residents, incentives should be adopted to strategically retrofit buildings where both socially vulnerable populations reside and increasing temperatures are forecast.

Recent climatic trends show more flooding and extreme heat events and in the future transportation infrastructure may be susceptible to more frequent and intense environmental perturbations. Our transportation systems have largely been designed to withstand historical weather events, for example, floods that occur at an intensity that is experienced once every 100 years, and there is evidence that these events are expected become more frequent. There are increasing efforts to better understand the impacts of climate change on transportation infrastructure. An abundance of new research is emerging to study various aspects of climate change on transportation systems. Much of this research is focused on roadway networks and reliable automobile travel. We explore how flooding and extreme heat might impact passenger rail systems in the Northeast and Southwest U.S.

In the spring of 2016, the City of Apache Junction partnered with the School of Geographical Sciences and Urban Planning at Arizona State University on three forward-thinking plans for development in Apache Junction. Graduate students in the Urban and Environmental Planning program worked alongside City staff, elected officials and the public to identify opportunities and visions for:
       1. Multi-modal access and connectivity improvements for City streets and open space.
       2. Downtown development.
       3. A master-planned community on state land south of the U.S. 60.

The following sections of the report present Apache Junction’s unique characteristics, current resident demographics, development needs and implementation strategies for each project:
       1. Community Profile
       2. Trail Connectivity Master Plan
       3. Downtown Visioning
       4. State Land Visioning

The Trail Connectivity Master Plan optimizes existing trails and wide road shoulders to improve multi-modal connections across the city. The proposed connections emphasize access to important recreation, education and other community facilities for pedestrians, equestrians and bicycles. Trail and lane designs recommend vegetated buffers, wherever possible, to improve traveler safety and comfort. The proposals also increase residents’ interaction with open space along urban-rural trails and park linkages to preserve opportunities to engage with nature. The objectives of the report are accomplished through three goals: connectivity, safety improvements and open space preservation.

Downtown Visioning builds on a large body of conceptual design work for Apache Junction’s downtown area along Idaho Road and Apache Trail. This report identifies three goals: to establish a town center, to reestablish the grid systems while maintaining a view of the Superstition Mountains, and to create an identity and sense of place for the downtown.

State Land Visioning addresses a tract of land, approximately 25 square miles in area, south of the U.S. 60. The main objective is to facilitate growth and proper development in accordance with existing goals in Apache Junction’s General Plan. This is accomplished through three goals:
       1. Develop a foundation for the creation of an economic corridor along US-60 through
           preliminary market research and land use planning.
       2. Create multi-modal connections between existing development north of US-60 and
           future recreational space northeast of US-60.
       3. Maintain a large ratio of open space to developed area that encompasses existing
           washes and floodplains using a master planned community framework to provide an
           example for future land use planning.