New Tool Helps Decision Makers Predict Colorado River’s Future

The Colorado River is a vital source of water for the western United States, providing drinking water to homes and irrigation water to farms in seven states, but the watershed is increasingly affected by climate change and drought. A new computational tool developed by a research team led by Pennsylvania State University scientists may help the region adapt to a complex and uncertain future.

Their tool, the Framework for Narrative Storyline and Impact Taxonomy (FRNSIC), can help decision makers explore many possible futures and identify key scenario storylines (explanations of what important futures could be like) to help planners better deal with the uncertainties and impacts brought about by climate change. They published their findings on September 19 in the journal Earth’s Future.

“One way states like Colorado can prepare for the future is to plan for how things might change, based on available science and input from a variety of stakeholders,” said Antonia Hajimichael, an assistant professor in Penn State’s Department of Geosciences and lead author of the study. “This scenario planning process recognizes that planning for the future involves a lot of uncertainty about climate and water demand, so planners need to consider a range of possibilities, including scenarios with rapid warming and scenarios with gradual warming.”

Hajimichael said the scientific community and decision-makers around the world often turn to scenarios to explain what future conditions might be, but this approach can only consider a few possibilities and neglect other options.

These scenario planning approaches often feature a relatively small number of scenarios (e.g. what drought conditions would be like under different levels of warming) and may not capture the complexity of all the factors involved.

Alternatively, scientists use a technique called exploratory modeling, in which models simulate thousands or even millions of possible futures to discover which ones matter. But this approach is often impractical for decision makers to use, the scientists say.

“We wanted to offer something in between,” Hajimichael says, “something that bridged the two, something that took into account the complexities but made it a little more practical and a little less daunting.”

Their tool, FRNSIC, first uses exploratory modeling to explore a large number of hypothetical future conditions, then uses the data to categorize and identify storylines that are relevant and locally meaningful, the scientists said.

“Our approach is basically looking at possible future impacts and then saying, ‘For this stakeholder, this is the storyline that matters most. And for other stakeholders, here’s another storyline that they should be worried about,'” Hajimichael says. “It adds a bit more plurality and nuance to how we set up planning scenarios.”

In the Colorado River Basin, decision-makers face a complex set of factors, including how to provide enough water for a growing population and farmers while also ensuring the state doesn’t use more than its permitted allocation of river flows, Hajimichael said.

“The problem is there’s no single measure that captures everyone and what they care about,” she said. “Your farm may be very big, my farm may be very small, and we may grow different things. It’s hard to use any single factor to find a scenario that will make us all happy or make us all unhappy.”

The storylines developed by FRNSIC can be used for future work in the Colorado River Basin, for example, how drought events might be affected if the population adapts and changes.

“This allows policymakers to look at different situations around the world and consider how different interventions would affect the basin under each scenario,” Hajimichael said. “These drought scenarios can be used to highlight potential outcomes and therefore can be used when negotiating and consulting with stakeholders.”

Also contributing to the study were Cornell University professor Patrick Reed, University of Virginia assistant professor Julian Quinn, geospatial scientist Chris Vernon and software engineer Travis Thurber of the Pacific Northwest National Laboratory.