NASA project helps water managers in a warming world

New NASA project helps water managers in a warming world
Elizabeth Goldbaum, July 2019, elizabeth.f.goldbaum@nasa.gov

 

How does global climate change play out locally in your community? A new NASA tool charts out what rising world temperatures will mean for local water resources.

U.S. Geological Survey Streamgage on Fourmile Creek in Colorado during 2013 flood. Credit: USGS.

Drab, murky water recently inundated a town in Iowa, leaving only the very tops of sloped roofs and skinny trees visible from the air.

Areas around the country, particularly in the upper Mississippi and Missouri River basins, have experienced record flooding this year. The Mississippi River basin spans 31 states and provides drinking water for 20 million people.

In other parts of the country, too little water is a primary concern. Droughts in the Upper Colorado River Basin have been getting more widespread and severe over the past 50 to 90 years as less rain and snow fall over the region. The basin provides drinking water, agriculture and recreation for nearly 40 million people.

To help water managers prepare for these climate change-related impacts to water systems, a NASA-funded team led by researchers at the National Center for Atmospheric Research in Boulder, Colorado are creating tools to make global climate change predictions local.

The effort aims to help water managers at the local, state and federal level more easily understand how climate change compromises water security for communities, said Andy Wood, a scientist at NCAR leading the effort. Wood took over the project from Martyn Clark, now a collaborator and professor at the University of Saskatchewan in Canada.

Climate change can increase water demand while limiting its availability, according to the National Climate Assessment. As winter precipitation that once fell as snow changes to rain, water flows into reservoirs, lakes and rivers at different times of the year than it has historically, said Jeff Arnold, a co-investigator on the project and a scientist with the U.S. Army Corps of Engineers (USACE). The USACE wants to know how much change to expect across the U.S. in the next 50 to 100 years, Arnold said, since that can impact how the agency operates its infrastructure, like dams and hydropower plants, on water systems.

The tools developed by the project will enable water managers to create strategies to modernize and maintain their infrastructure, Wood said, in order to address water security at the local level. “Water security is having the right amount of water at the right time and at the right place,” Arnold said.

From global to local perspectives

To bring water managers localized information, Wood’s team is creating and sharing software, maps and datasets that localize global projections.

“We have changes coming out of global climate models that tell us really big picture patterns,” said Ethan Gutmann, a co-lead and scientist at NCAR. The global view may reveal how the atmosphere is likely to change, but it doesn’t necessarily get down to how a specific basin is going to change, Gutmann said, because the global models run at a low spatial resolution. For instance, the global approach often doesn’t capture the mountains that created a particular river basin, Gutmann said.

To overcome this issue, Gutmann downscaled the global model climate projections, which means that instead of looking at an area that measures 100 by 100 miles, or approximately the size of the state of Maryland, he zoomed in on an area that’s 5 by 5 miles, which is roughly the size of Disney World in Orlando, Florida.

The team then connected Gutmann’s model outputs to the NASA Land Information System (LIS) to help characterize the downscaled climate change impacts on water resources on a watershed-by-watershed basis, since water managers often have jurisdictions based on watersheds, Wood said.

Wood is also developing predictions to determine when water flows into reservoirs to help federal water managers ensure water is available to both rural and densely populated areas.

“We are supporting the infrastructure to make the climate simulations and climate downscaling work much easier to set up for new groups interested in this kind of analysis,” Guttmann said.

Cracked brown soil. (Credit: Charl Van Rooy)

From global to local perspectives

To make the work more meaningful and assessible to water managers, the team included and reached out to them from the start of the project.

“What matters to water managers is understanding the range of possibilities that could result from different localized climate projections,” said Christa Peters-Lidard, a co-lead and Deputy Director for Hydrosphere, Biosphere, and Geophysics in the Earth Sciences Division at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “For instance, for each climate projection, you get different outcomes for streamflow, runoff and evapotranspiration,” Peters-Lidard said

“We really need to resonate with people so they don’t just see the uncertainty and say, this is just too much, I’m not going to use this information,” said Julie Vano, a scientist and team member at NCAR.

To help users navigate the uncertainties, Vano has shared the team’s work with public municipal utilities like Denver Water, which serves over one million people. A simple assessment projects a seven percent loss in water supply if their region experiences a two-degree Fahrenheit average temperature increase, primarily due to accelerated evaporation. The utility is preparing for this and other possible futures to be more resilient amid climate uncertainty.

Vano also gathered feedback from water managers to understand their needs. For instance, in the Pacific Northwest, water managers have to decide how much water to release for hydropower generation and other uses based on how much snowmelt will feed the system. Since they make this decision every year at the same time, they need to know whether potential long term changes in the seasonality of water supply could lead to changes in the best way to manage river flows.

We’re putting together “dos and don’ts” guidance for how to use climate information in water planning and management, Vano said, and building relationships with decision makers.

Our hope is that the new tools and data sets that come out of this project will allow us to characterize the uncertainties for smaller regions, Arnold said, so that water managers can make more informed decisions for the uncertain future.