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- All Subjects: Environmental Studies
- All Subjects: Urban Heat Islands
- Creators: Hirt, Paul W.
- Creators: School of Geographical Sciences and Urban Planning
- Status: Published
In light of climate change and urban sustainability concerns, researchers have been studying how residential landscape vegetation affect household water consumption and heat mitigation. Previous studies have analyzed the correlations among residential landscape practices, household water consumption, and urban heating at aggregate spatial scales to understand complex landscape decision tradeoffs in an urban environment. This research builds upon those studies by using parcel-level variables to explore the implications of vegetation quantity and height on water consumption and summertime surface temperatures in a set of single-family residential homes in Tempe, Arizona. QuickBird and LiDAR vegetation imagery (0.600646m/pixel), MASTER temperature data (approximately 7m/pixel), and household water billing data were analyzed. Findings provide new insights into the distinct variable, vegetation height, thereby contributing to past landscape studies at the parcel-level. We hypothesized that vegetation of different heights significantly impact water demand and summer daytime and nighttime surface temperatures among residential homes. More specifically, we investigated two hypotheses: 1) vegetation greater than 1.5 m in height will decrease daytime surface temperature more than grass coverage, and 2) grass cover will increase household water consumption more than other vegetation classes, particularly vegetation height. Bivariate and stepwise linear regressions were run to determine the predictive capacity of vegetation on surface temperature and on water consumption. Trees of 1.5m-10m height and trees of 5m-10m height lowered daytime surface temperatures. Nighttime surface temperatures were increased by trees of 5m-10m height and decreased by grass. Houses that experienced higher daytime surface temperatures consumed less water than houses with lower daytime surface temperatures, but water consumption was not directly related to vegetation cover or height. Implications of this study support the practical application of tree canopy (vegetation of 5m-10m height) to mitigate extreme surface temperatures. The trade-offs between water and vegetation classes are not yet clear because vegetation classes cannot singularly predict household water consumption.
Infrastructure is not static, but dynamic. Institutions play a significant role in designing, building, maintaining, and upgrading dynamic infrastructures. Institutions create the appearance of infrastructure stability while dynamically changing infrastructures over time, which is resilience work. The resilience work of different institutions and organizations sustains, recovers, adapts, reconfigures, and transforms the physical structure on short, medium, and long temporal scales.
To better understand and analyze the dynamics of sociotechnical infrastructure resilience, this research examines several case studies. The first is the social and institutional arrangements for the allocation of resources from Hoover Dam. This research uses an institutional analysis framework and draws on the institutional landscape of water and energy systems in Arizona. In particular, this research illustrates how institutions contribute to differing resilience work at temporal scales while fabricating three types of institutional threads: lateral, vertical, and longitudinal threads.
This research also highlights the importance of institutional interdependence as a critical challenge for improving infrastructure resilience. Institutional changes in one system can disrupt other systems’ performance. The research examines this through case studies that explore how changes to water governance impact the energy system in Arizona. Groundwater regulations affect the operation of thermoelectric power plants which withdraw groundwater for cooling. Generation turbines, droughts, and water governance are all intertwined via institutions in Arizona.
This research, finally, expands and applies the interdependence perspective to a case study of forest management in Arizona. In a nutshell, the perilous combination of chronic droughts and the engineering resilience perspective jeopardizes urban water and energy systems. Wildfires caused by dense forests have legitimized an institutional transition, from thickening forests to thinning trees in Arizona.