American Society of Landscape Architects Recognizes U of A Students’ Smart Watering Project

A group of University of Arizona researchers, received a landmark achievement for their project, “Smart Tree Watering in Southern Arizona’s Urban Environment.” The award is the highest honor given by the ASLA. The team will accept their award in Washington D.C. in October and present their research to industry professionals.

“I remember waking up, checking my phone, and seeing the email that said we won. I sent it to everyone on the team as fast as I could. It was such an incredible feeling. I didn’t even need coffee that morning,” said Annalise Hummel, a member of the research team and graduate student studying landscape architecture. 

As Arizonans continue to face extreme heat and rising temperatures, there is a need for sustainable, cost-effective ways to adapt. By using smart watering techniques on trees, Hummel and the research team set out to provide shade while also reducing water usage, creating a safer and healthier urban environment for Tucson.

The project, funded by a grant from the Arizona Board of Regents, involved planting a total of more than 80 Desert Willow, Hackberry, Ironwood, and Joan Lionetti Live Oak trees—all species that are native to Arizona or have a history of surviving and performing well in the Sonoran Desert.

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The team then treated the trees with one control treatment–drip irrigation watering–and four basin water collection techniques: rainwater harvesting, organic mulch, and two types of hydrogels, one made of cellulose, and the other made of plastic. Hydrogels are small bead-shaped containers that house water and are stored near the tree's roots. The hydrogels swell with water and release it when the roots of the tree dry up. They used sensors to constantly monitor and collect data.

Their research found that all the smart watering techniques increase soil moisture and decrease soil temperature while maintaining healthy tree growth. The trees receiving experimental treatments used far less water compared to trees receiving traditional municipal watering techniques.

In addition to Hummel, the project team included Christian Aguilar Murrieta and Cordell Lee, also graduate students in CAPLA, as well as researchers Zhihua Wang and Tianfang Xu from Arizona State University. Project advisors were Vanessa Buzzard, senior research specialist in the School of Natural Resources and the Environment; Grant McCormick, Director for Enterprise GIS and adjunct professor in the College of Agriculture, Life & Environmental Sciences (CALES); Douglas Loy, professor in the College of Engineering and the College of Science; Shujuan Li, professor in CAPLA, and the Principal Investigator, Bo Yang, CAPLA’s associate dean for research. 

“Utilizing trees to provide shade has immense health benefits, not only physically as protection from the sun, but psychologically too,” said Yang, “green environments make residents happier. This project proved that we can use nature to create healthy built environments for all people.”

“This is a story about helping people—not just about using less water and creating greener urban communities,” said Hummel. “The environments people live in have an astounding impact on their lives. It’s about improving the lives of communities across the arid southwest using scalable, low-cost tools.”