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Pavement temperature effects on overall urban heat island

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In recent years, an increase of environmental temperature in urban areas has raised many concerns. These areas are subjected to higher temperature compared to the rural surrounding areas. Modification of land surface and the use of materials such as concrete and/or asphalt are the main factors influencing the surface energy…

In recent years, an increase of environmental temperature in urban areas has raised many concerns. These areas are subjected to higher temperature compared to the rural surrounding areas. Modification of land surface and the use of materials such as concrete and/or asphalt are the main factors influencing the surface energy balance and therefore the environmental temperature in the urban areas. Engineered materials have relatively higher solar energy absorption and tend to trap a relatively higher incoming solar radiation. They also possess a higher heat storage capacity that allows them to retain heat during the day and then slowly release it back into the atmosphere as the sun goes down. This phenomenon is known as the Urban Heat Island (UHI) effect and causes an increase in the urban air temperature. Many researchers believe that albedo is the key pavement affecting the urban heat island. However, this research has shown that the problem is more complex and that solar reflectivity may not be the only important factor to evaluate the ability of a pavement to mitigate UHI. The main objective of this study was to analyze and research the influence of pavement materials on the near surface air temperature. In order to accomplish this effort, test sections consisting of Hot Mix Asphalt (HMA), Porous Hot Mix asphalt (PHMA), Portland Cement Concrete (PCC), Pervious Portland Cement Concrete (PPCC), artificial turf, and landscape gravels were constructed in the Phoenix, Arizona area. Air temperature, albedo, wind speed, solar radiation, and wind direction were recorded, analyzed and compared above each pavement material type. The results showed that there was no significant difference in the air temperature at 3-feet and above, regardless of the type of the pavement. Near surface pavement temperatures were also measured and modeled. The results indicated that for the UHI analysis, it is important to consider the interaction between pavement structure, material properties, and environmental factors. Overall, this study demonstrated the complexity of evaluating pavement structures for UHI mitigation; it provided great insight on the effects of material types and properties on surface temperatures and near surface air temperature.
ContributorsPourshams-Manzouri, Tina (Author) / Kaloush, Kamil (Thesis advisor) / Wang, Zhihua (Thesis advisor) / Zapata, Claudia E. (Committee member) / Mamlouk, Michael (Committee member) / Arizona State University (Publisher)
Created2013
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¹³⁷Cs and ²¹⁰Pb in the San Gabriel Mountains, California: erosion rates, processes and implications

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Numerous studies have examined the interplay of climate, tectonics, biota and erosion and found that these variables are intertwined in a complicated system of feedbacks and as a result, some of these factors are often oversimplified or simply neglected. To understand the interplay of these factors one must understand the…

Numerous studies have examined the interplay of climate, tectonics, biota and erosion and found that these variables are intertwined in a complicated system of feedbacks and as a result, some of these factors are often oversimplified or simply neglected. To understand the interplay of these factors one must understand the processes that transport or inhibit transport of soil. This study uses the short-lived, fallout-derived, radionuclides 137Cs and 210Pb to identify soil transport processes and to quantify soil transport using the profile distribution model for 137Cs. Using five field sites in the San Gabriel Mountains of California, I address four questions: (1) Is there a process transition between high and low gradient slopes observable with short-lived isotopes? (2) Do convex hilltops reflect short-term equilibrium erosion rates? (3) Do linear transects of pits accurately characterize hillslope averaged erosion rates? and (4) What role does fire play on short-term soil transport and isotope distribution? I find no evidence supporting a process transition from low gradient to high gradient slopes but also find that significant spatial variability of erosion rates exist. This spatial variability is the result of sensitivity of the method to small scale variations in isotopes and indicates that small scale processes may dominate broader scale trends. I find that short-term erosion rates are not at equilibrium on a convex hilltop and suggest the possibility of a headward incision signal. Data from a post-fire landscape indicates that fires may create complications in 137Cs and 210Pb distribution that current models for erosion calculation do not account for. I also find that across all my field sites soil transport processes can be identified and quantified using short-lived isotopes and I suggest high resolution grid sampling be used instead of linear transects so that small scale variability can be averaged out.
ContributorsWalsh, Joseph Robert (Author) / Heimsath, Arjun M. (Thesis advisor) / Whipple, Kelin X. (Committee member) / Zapata, Claudia E. (Committee member) / Arizona State University (Publisher)
Created2011