If you travel up stream to the tip-top of the headwaters in the San Juan Range of the Colorado Rockies, you'll reach the very beginning of the Rio Grande River, and what happens at the very top helps determine the quality and quantity of water that we use every single day. Those beginnings are what researchers refer to as headwater stream networks, making up nearly 80 percent of river miles on earth. However, they are also some of the most overlooked areas in research within the academy.
Now, with the help of a $2.5M grant awarded by the Department of Energy, The University of New Mexico (UNM) will lead a group of researchers who will concentrate on five very different headwater stream networks spread across the U.S. continental precipitation gradient.
"Headwater stream networks are vital to downstream ecosystems," said Alex Webster, UNM assistant professor and principal investigator on the project.
The proposal, Integrating catchment expansion-contraction intro cross-continental hydrybiogeochemical prediction, was submitted through UNM's Center for the Advancement of Spatial Informatics Research and Education and investigators will begin their work next month.
"Historically, we treated these headwater watersheds like black boxes. We tend to care about how much water comes out of them and the quality of that water but not so much about the reasons why," Webster said. "There is a lot going on in them, they are changing very quickly because they are very sensitive to climate change, including to changes in snowpack, and because that's where streams tend to dry up first."
Researchers are planning to study five headwater watersheds, which include:
- Upper Santa Fe River Watershed in New Mexico | Drains into the Santa Fe River
- Dog Creek Watershed in Nevada | Drains into the Truckee River
- South Sandy Creek in Alabama | Drains into the Black Warrior River
- Richland Creek in Arkansas | Drains into the White River Basin
- Lamprey River in New Hampshire | Drains into the Great Bay Estuary
Webster, who was originally hired through UNM's Sustainable Water Resources Grand Challenge team as a research professor, says the two-year project will happen in three stages. With the help from a group of researchers at The University of Oklahoma, the first stage will include hydrologic modeling – where researchers will simulate processes and help predict what entire watershed stream networks are doing based on observations of waterflow, precipitation and other factors. The second stage includes understanding the spatial structure of each watershed in terms of how it influences water quality and quantity. The third and final part of the project will look at how all this changes throughout time in response to changing patterns of precipitation and drought.
Headwater watersheds are complex systems that are still poorly understood. When it rains, headwater stream networks expand, and when more water is flowing the overall network gets larger. When the climate changes and it's dry outside, headwater stream networks contract as streams dry up. According to Webster and her team of researchers from the University of Alabama, University of Arkansas, University of Nevada – Reno, University of Oklahoma, and the University of New Hampshire, this process is incredibly important in determining the amount of water and quality of water that ends up downstream.
"As the stream network dries up, we get less water downstream, but the important question is if something happens in one part of the watershed, is that going to have a bigger impact compared to if it happened in other parts of the watershed? That sort of understanding will be incredibly helpful for water management," Webster said.
The group of researchers will also work in collaboration with Oak Ridge National Laboratory to compare and contrast watershed findings to one being studied in Tennessee. Researchers say this study will impact future research and will provide essential infrastructure investment that will enable states to better monitor and manage the water quality and quantity that headwater streams export to downstream waters.
"When we're done, I think we'll have a better understanding of these headwater streams and how they work in these different locations," Webster said. "A lot of states, like New Mexico, rely on the Clean Water Act to enforce issues related to water quality. Because they don't all flow year around, headwater streams are especially vulnerable to changes in what the Clean Water Act protects, which lately has changed with every administration. Therefore, we need to continue to make the argument regarding the importance of headwater stream networks and keep that conversation going on a federal and state level."
** Co-investigators on the project include Arial J. Shogren, Joanna Blaszczak, Yang Hong, Shannon L. Speir, and Adam Wymore.
