Barrett, The Honors College Thesis/Creative Project Collection

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.

This project was inspired by Dr. Kelli L. Larson’s research which disproved three common landscaping misconceptions in the Phoenix Valley. The first misconception states that newcomers, not long-time Phoenicians more often have and prefer grassy lawns instead of xeric, desert-adapted landscapes when actually the opposite is true. Secondly, the rise in xeric landscapes is not due to personal choice but rather a variety of other factors such as developer decisions. Finally, Dr. Larson’s research also disproves the assumption that people who possess pro-environmental attitudes correspondingly demonstrate sustainable landscaping behavior, and finds that people with those attitudes actually tend to irrigate more frequently in the winter months. Debunking these misconceptions is important because the long-term impacts of global climate change could have effects on water use in the desert southwest, and promoting water conservation in urban residential landscaping is an important step in the creation of sustainable water use policy. <br/><br/>The goal of my project was to make this information more accessible to broader public audiences who may not have access to it outside of research circles. I decided to create a zine, a small batch, hand-made mini-magazine, centered around disproving these myths so that the information could be distributed to broader audiences. I conducted informal stakeholder interviews to inform my design in order to appeal to those audiences, and constructed a 16-page booklet which debunked the myths and encouraged critical thinking about individual water use and urban landscaping habits. The zine included hand-painted illustrations and was constructed as a physical copy with the intention of eventually copying and distributing both a physical and digital version. The purpose of this project is to create a way of accessing reliable information about urban landscaping for residents of the Phoenix Valley, where the climate and geography necessitate water conservation.