Five questions for Edie Zagona

Growing up in the desert informs professor’s research in water management

As she grew up in the Sonoran Desert in Arizona, Edie Zagona learned how important water and nature’s cycles were to the land and its people. The lesson never faded.

Although she majored in philosophy as an undergraduate – and especially loved the philosophy of science -- she was discouraged “by the improbability of finding lifelong gainful employment.” She already had taken a number of math and science classes, and when it was time to determine her next area of study, she realized her science background had taken her halfway to an engineering degree. It was then she knew she would pursue a career in water resources.

After studying civil engineering at the University of Arizona, she worked at the Bureau of Reclamation, where she helped design the Central Arizona Project, which now brings water from the Colorado River at Lake Havasu across the desert to Phoenix and Tucson. Later, with a master’s from Colorado State University, she worked at Reclamation’s Arizona Projects Office, coordinating the work of engineers with concerns of environmentalists and the public in the final design of a segment of canal that crosses the Sonoran Desert.

“I felt that my work there contributed to the final solution that preserves the fragile ecosystem as well as the visual beauty of the area. As that project came to a close, I felt the urge to continue my education,” she said.

She heard about a new research center at the University of Colorado Boulder led by Kenneth Strzepek. It focused on bringing system analysis and nascent decision support science to water management problems. She joined the Center for Advanced Decision Support for Water and Environmental Systems (CADSWES) and earned her doctorate. She remained at the center and is currently a research professor in the Civil, Environmental and Architectural Engineering Department, and since 2002, the center’s director.

One of her favorite achievements is the success of RiverWare, a software for which she has led development, which models a variety of situations such as drought, floods – even climate change – to help managers and operators of river and reservoir systems determine current and future water use and storage strategies. RiverWare is now widely used by agencies and others throughout the U.S. and increasingly abroad. Another achievement: successful graduate students who “are stars in their performance and contributions to improving water management.”

Her passion for nature often carries her to the mountains for hikes, a connection she says she needs to thrive.

“I find that my most creative thoughts and problem-solving arise while walking,” she said.

Frequent visits to southern Arizona and the Sonoran Desert keep her connected to her roots. She plays tennis, is an avid reader of fiction and nonfiction, and loves to cook – her family has owned an Italian restaurant for more than 75 years.

“But with little time to cook, I have transferred the passion and techniques to my husband and daughter, both of whom can perform magic in the kitchen.”

1. Why did you create RiverWare and how has this software changed the process of water management?

RiverWare grew out of the need of water management agencies to have a river system simulation software that is easy to use, transparent with respect to behavior, and that can represent multi-objective operating policies in a way that everyone, including stakeholders, can understand. The design of RiverWare is a direct response to new challenges in water management over the past few decades, including environmental laws, climate change, power deregulation, intense stakeholder involvement and increasing demands in the face of decreasing availability of fresh water supplies.

We are fortunate to collaborate closely with visionary technical leaders in the three largest water management agencies in the U.S. – the Bureau of Reclamation, the Tennessee Valley Authority and the U.S. Army Corps of Engineers. These forward-thinking water managers have worked with us for the past 20 years in defining the needs for tools that can result in improved management. The needs constantly evolve and we constantly enhance and extend the tools.

Because of its flexible architecture, RiverWare can be used in many different ways depending on the purpose of the application. For example, it can produce an optimal reservoir and hydroplant operations schedule depending on water demands, environmental flow requirements and the value of hydropower produced. It can project operations over the next few weeks or months given current conditions, operating policies, weather predictions and snowpack measurements so that water consumers, recreationalists and power producers can prepare; this includes the need for communities to prepare for extreme events such large floods or severe droughts.  RiverWare can model a combination of different future hydrologic scenarios, demand scenarios and policy alternatives, producing risk-based results to help planners and policy makers plan future development or evaluate proposed policies. It can model water ownership and allocate water based on water rights priorities; it is used by several agencies to record official water accounting. It is commonly used for water availability studies to understand the reliable water supply that can be expected, given hydrologic scenarios and reservoir sizes.

2. The software uses “1,200 years of paleo hydrology as the basis for planning studies.” First, how was 1,200 years of data collected? Second, how have you incorporated potential future issues such as climate change or other unexpected events into the software?

Water management policies are predicated on an understanding of hydrologic variability – the policies must address how to manage the water for all the various needs in wet, dry and average conditions, and sometimes in extended drought periods or extreme flood events. How do hydrologists know the nature of future hydrologic variability? The past record of stream flows is used to understand the statistical characteristics of the variability; the longer the historic record, the better the understanding of what the future may bring. Tree ring science has produced “reconstructed” hydrology for many years before stream gaging began. In the Colorado River Basin, this “paleo” record goes back about 1,200 years. Scientists, including our collaborators at CU and Reclamation, have developed statistical techniques for using the paleo record to generate possible future hydrologic scenarios that can be used in developing and evaluating proposed management policies. We have designed RiverWare to easily model these possible future scenarios. Likewise, climate change scenarios that are developed using global climate models can be incorporated into RiverWare to project future conditions that assume the future will be different from the past.

3. Have you done other research focused on hydrology?

We have recently been engaged in research projects aimed at understanding the role and limitations of using hydropower as a balancing reserve for integrating wind energy into the power grid. Wind’s variability and uncertainty pose a challenge for power system managers who must constantly match power supply exactly with power demand, which also is variable. Hydropower is an ideal power source to balance wind because it can be quickly switched online and off or ramped up and down. Past studies to estimate the ultimate potential penetration level of wind energy in the power mix have not considered the other often complex objectives and constraints of the water such as supply, environmental flows, flood control, navigation, recreation, etc.

We collaborate with other researchers, most often with Professor Balaji Rajagopalan, a colleague in civil engineering, on graduate student research that improves techniques for forecasting stream flow and demonstrates their uses in decision-making via RiverWare applications of specific river basins.

4. You spent some time in Africa as a water resources adviser. How did that come about and what are some of your favorite memories from your work there?

I was invited to be a technical adviser to the Nile Basin Initiative in developing a decision support system for use by the 10 Nile Basin countries for collaborative decision-making about future development of the water resources in the basin. I shared my knowledge and experience gained at CADSWES with the excellent team of African experts who managed the project. The four-year project has just been completed. The system will be deployed in the coming months with a support team to ensure that the countries will use it to evaluate proposed development strategies, identify win-win plans, analyze tradeoffs and plan for climate change.

My favorite aspect of this work was interacting with the experts from the countries, especially as they described the water resources issues in their respective parts of the basin with detailed understanding of the hydrologic processes as well as the social and environmental concerns. This was an opportunity for me to see a different set of decision support needs. I took away at least as much as I contributed to this interesting project. I feel a deep connection to Africa now that I did not have before and hope to be involved in future work there.

5. What concerns and heartens you about our own water-use policies? 

My greatest concerns are the continuing degradation of riparian ecosystems here and around the world, and the uncertainty about future conditions brought about by climate change. The management of water resources for a sustainable future is a monumental challenge for the human race. I am most heartened to see the dedication of people at many levels to improved and sustainable water management. The growing cooperation and collaboration among public agencies, stakeholders, NGOs, scientists and policymakers that was not seen a few decades ago is a hopeful sign that we can develop creative technical solutions and have the will to make difficult decisions.