Tracking water’s footprint in agriculture

If you’ve ever walked, jogged or biked along the local canals or Tempe Town Lake, you have experienced the benefits of the city’s water management infrastructure. Across the United States, water is ingrained in daily life in many ways, but arguably none are more important than its use for agriculture.

Sustainable water management focuses heavily on the amount of water extracted from natural sources. Known as water withdrawal, this method helps farmers sustain their crop fields. When it comes to advancing researchers’ understanding of water withdrawal, the next frontier is tracking where water wanders.

Ruijie Zeng, an assistant professor of civil, environmental and sustainable engineering in the School of Sustainable Engineering and the Built Environment, part of the Ira A. Fulton Schools of Engineering at Arizona State University, is working to explore those paths by analyzing decades of survey data measuring water withdrawal across the contiguous United States.

Wading through data

Zeng’s research explores the intersection of how water circulates on Earth, known as the hydrologic cycle, and how to optimize water use to fulfill societal needs. He is analyzing approximately 40 years of data provided by the U.S. Geological Survey, which consists of about 40 years of surveys measuring water withdrawal allocated for agriculture on national, regional and state levels.

In his most recent publication in the scientific journal Environmental Research Letters, Zeng describes how he used survey data to determine the center of mass in a given water source. He then compared how the location of the center varies every five years to assess the impacts of water withdrawals. 

“I want to look at the impact of large-scale hydraulic infrastructures that are impacting the natural environment and socioeconomic development,” Zeng says. “Furthermore, we are exploring how to effectively manage the existing infrastructure to adapt to changing conditions.”

Zeng’s analysis suggests irrigation methods in the Western United States use more efficient technology than on the East Coast, largely because of the need to combat potential drought conditions. Meanwhile, the East Coast is experiencing accelerated water withdrawal due to the rapid expansion of fields to keep up with population growth. Both coasts, he says, have room for improvement.

Though his analysis has focused on water withdrawal on a national scale, he intends to make his results accessible to help other researchers identify influential factors within specific regions.

“We believe that observing the trends of agricultural water withdrawal will provide a simple and meaningful way to summarize the condition of the nation’s water landscape,” Zeng says.

Changing tides

Agricultural irrigation is the largest sector for water consumption in the U.S., taking up a staggering 72% of the available water supply. Agriculture is a primary source of the nation’s food supply, provides access to biofuel and energy supplies and supports the global trade of vital resources. Without a dependable water supply for agricultural irrigation, environmental and socioeconomic stability would decline. 

Now more than ever, climate change is also disrupting the predictability of natural water systems, which subsequently disrupts countless industries and has the potential to trigger major socioeconomic consequences. Such erratic changes in reliable access to water can have a ripple effect across the world.

In our own backyard

Gaining a deeper understanding of water irrigation through research is not the epilogue to the story of water management but instead a chapter in an ongoing saga of exploring the hydrologic cycle. By observing potential trends, researchers and policymakers can develop solutions that trickle down to farmers, which can help sustain large metropolitan areas and the environment.

A collaboration between ASU, the Central Arizona Project, the Salt River Project and other local infrastructure managers is helping Phoenix-area residents sustain water security.

ASU continues to demonstrate its commitment to sustainable water supply practices with the launch of the Center for Hydrologic Innovations. The new center aims to position ASU as a global leader in the development, use and dissemination of hydrologic innovations with public impact through research in Arizona and throughout the arid Western U.S.

Zeng says ASU is an ideal home base for solving water management problems, given the high value surrounding communities put on water security. Because of this value, the desert metropolitan area is ideal for emerging research and innovative efforts to mitigate water resource challenges — and Zeng says he has found ASU to be an excellent environment for collaboration and support.

Insights from the study will help researchers develop technology to enhance the prediction capability of hydrologic models. As policymakers, corporations and farmers tackle future challenges, Zeng’s advanced models will provide scientific evidence to make informed water management decisions.