Overeem

Desert reservoirs capture and store organic carbon, according to new research

Gabe Allen — Thu, 03 Apr 2025 19:00:00 +0000

Desert reservoirs capture and store organic carbon, according to new research Gabe Allen Thu, 04/03/2025 - 13:00

Gabe Allen

A new investigation from Abby Eckland, Irina Overeem and collaborators reveals a surprising climate benefit of damming in the desert.

In 2021, while revelers across America celebrated the fourth of July, three researchers waded through a shallow river delta in the New Mexican desert. Abby Eckland, Irina Overeem and Brandee Carlson stood in what remained of the Rio Grande—years of drought had shrunk the river to a few small channels. Just downstream, the channels entered the Elephant Butte Reservoir—New Mexico’s largest.

Then, all of the sudden, the water started rising. First, to the scientists' calves. Then above their knees.

“Wow, it’s really coming up,” Overeem remarked.

The river became muddy and turbid. Debris—tamarisk leaves, pine needles and trash—floated down the widening channel. Dead fish rose to the surface and came to rest in the weeds on the riverbank. It was a flash flood.

At this point, a normal sightseer would probably head for the hills, but the scientists, instead, responded with excitement. This was an opportunity for inquiry into an ephemeral natural phenomenon. Eckland bottled up water samples while Overeem and Carlson checked on the sensing equipment they had placed in the river that morning.

A carbon sink in the desert

Abby Eckland (left) and Irina Overeem back at the motel after a muddy day of field work on July 5, 2021. Photo by Brandee Carlson.

This month, the team published a new study, led by Eckland, in Water Resources Research. The analysis draws on their 2021 field season and parses information about sediment and organic carbon in river water for a surprising result. Reservoirs like Elephant Butte may sequester organic carbon within layers of sediment, especially during periods of drought and flash floods. Essentially, the reservoir acts as a carbon sink—trapping organic material that would otherwise emit carbon dioxide through natural decay.

A sonar system mounted to the front of Eckland’s packraft measures underwater river geometry on the Rio Grande near Elephant Butte Reservoir. Photo by Abby Eckland.

The explanation lies in physics. Normally, when water flows into a reservoir, it spreads out over the surface. But, if the river picks up enough sediment, the process flips upside down. Instead of the river water fanning out on top, an underwater current plunges it downward. Scientists call this a “hyperpycnal plume.”

“We saw this plume developing based on the data from instruments we casted near the mouth of the Rio Grande,” Eckland said. “That means that it’s likely that whatever sediment, carbon and other materials are being carried will flow to the bottom of the reservoir and get deposited.”

Armed with this evidence, the researchers next turned their attention to the samples they had gathered in the field. It was time to, literally, dig through the muck.

Droughts and floods

In the laboratory, an array of tests characterized the contents of samples from the river water, reservoir water, and underlying delta and reservoir beds. Once they had these values mapped out, the researchers compared their results to a repository of historical data from the U.S. Bureau of Reclamation—a process aided by Eckland’s familiarity with the system after years of interning with the Bureau. This allowed them to extrapolate their findings back in time.

“Abby had a lot of connections to the scientists there and knew what to look for,” Overeem said. “It was really good that we had this, sort of, liaison to the federal government system. It led to a unique partnership.”

Finally, the team had all of the information they needed to compare carbon sequestration in the river delta and reservoir over seasons, years and even decades.

This second set of analysis provided the study's most striking result. Not only was organic carbon getting buried beneath layers of sediment, but this process was actually amplified during drought. Because the overall footprint of the reservoir was smaller during these periods, sediment piled on faster.

“There’s less of a footprint when the water level is low,”Eckland said. “There’s just less space for it to go, so you get more carbon buried per area.”

The serendipitous timing of their field excursion produced another insight—carbon burial rates are also elevated during flash floods. It makes sense, of course. Flash floods tear through the landscape picking up loose soil, leaves and whatever else is lying around. By the time they reach the reservoir, they are full of sediment, which creates a hyperpycnal plume, and full of organic material, which is subsequently buried.

Though carbon burial in reservoir sediment has been observed in the past, the new paper is the first to identify exactly how it happens.

“The key link is the role of the hyperpycnal plume in delivering carbon to the bottom of the reservoir,” Eckland said.

Next steps

As with any novel scientific finding, the next step is to confirm the discovery and gather more information. This is already underway. Overeem recently returned to the site with former INSTAAR postdoc and current University of New Mexico assistant professor Marisa Repasch to gather samples from the reservoir bed. Repasch is an expert in organic carbon storage in the landscape, and her lab is hard at work digging deeper into the chemical characteristics of the sediment. So far, the preliminary results are promising.

“We found even higher numbers than what Abby estimated,” Overeem said.

The researchers are hopeful that these results might help water managers make more informed decisions in the future. Essentially, they have highlighted a unique benefit of dryland reservoirs—that they might capture and store the source material of Earth’s most ubiquitous greenhouse gas. This insight could become important in weighing potential costs and benefits of infrastructure on the landscape.

“There is renewed interest in carbon sequestration, especially because there might be a market for stored carbon at some point in the future,” Overeem said. “It’s a futuristic vision, but we will need this kind of information to get there.”

If you have questions about this story, or would like to reach out to INSTAAR for further comment, you can contact INSTAAR Communications Specialist Gabe Allen at gabriel.allen@colorado.edu.

Abby Eckland, Irina Overeem and collaborators investigate how a reservoir on the Rio Grande buries organic carbon beneath layers of sediment. The researchers found that the process is amplified during drought and flash floods.

Off

Traditional

The Elephant Butte Dam in 2022. Photo by Abby Eckland.

White

The Elephant Butte Dam in 2022. Photo by Abby Eckland.

CSDMS Spring School supports programming, modeling skills for Earth surface process research

Anonymous — Sun, 22 May 2022 06:00:00 +0000

CSDMS Spring School supports programming, modeling skills for Earth surface process research Anonymous (not verified) Sun, 05/22/2022 - 00:00

Shelly Sommer , INSTAAR

Twenty-five students from diverse backgrounds are in SEEC completing the CSDMS Spring School, a week-long coding camp designed to build students’ cyberinfrastructure skills needed in Earth science careers.

The Spring School is part of the annual meeting of the Community Surface Dynamics Modeling System (CSDMS) and is designed to allow participants to make advances on critical earth surface processes research questions by teaching cyberinfrastructure skills.

While field work and lab work get a lot of the glory in portrayals of Earth scientists, it can be programming and modeling that drive forward many Earth surface process research questions. “Earth sciences are a career that can be highly mathematical or computer intensive,” says Spring School founder and CSDMS deputy director Irina Overeem.

“Earth sciences as a discipline relies a lot on numerical modeling, so grad students will encounter some kind of data science problems and they need to foster skills in that area,” says Overeem. “We’re teaching a lot of the programming skills to deal with those types of problems.”

Students were immersed in hands-on training in numerical modeling, programming, open source software development, collaborative coding, version control, high-performance computing, and model uncertainty quantification.

While the CSDMS Spring School is in its third year, this is the first time it has been conducted in person. The first two years occurred online in response to the pandemic.

The cohort of students includes mostly graduate students with some postdoctoral fellows and early career faculty. They are from a number of universities and programs across the United States, with a few from international programs.

A central goal of the Spring School is professional networking: knitting together a cohort of people at the start of their careers who are all interested in Earth surface processes. Team exercises, mixers, and poster sessions are designed to build trust and collaboration between participants.

The students will attend the CSDMS annual meeting following the Spring School, to help them form more ties with the earth surface process modeling community.

“when I am at AGU, I will see a person from the University of Washington talking with a person from Colorado, and they seek each other out because of the connection they made during the workshop,” says Overeem.

25 students from diverse backgrounds are in SEEC completing the CSDMS Spring School, a week-long coding camp designed to build students’ cyberinfrastructure skills needed in Earth science careers.

Off

Traditional

White

CU �鶹ӰԺ team granted $2.56M to transform Earth surface science (CIRES)

Anonymous — Tue, 07 Dec 2021 07:00:00 +0000

CU �鶹ӰԺ team granted $2.56M to transform Earth surface science (CIRES) Anonymous (not verified) Tue, 12/07/2021 - 00:00

The National Science Foundation has awarded a highly competitive grant to a team of scientists building OpenEarthScape, a set of models and simulations to help anticipate changes in river flow, beach erosion, landslides and more. The $2.56M grant will support five years of work by earth surface scientists, including modelers, who are determined to better understand the forces that re-shape our landscapes over hours to epochs. Eric Hutton, Albert Kettner, Irina Overeem, Mark Piper are co-PIs on the grant.

Off

Traditional

White

Humans want stable landscapes; but rivers need to move (Univ. of Texas at Austin)

Anonymous — Fri, 23 Jul 2021 06:00:00 +0000

Humans want stable landscapes; but rivers need to move (Univ. of Texas at Austin) Anonymous (not verified) Fri, 07/23/2021 - 00:00

River deltas change over time, and the freedom to shift river location is important to maintaining a healthy ecosystem. However, humans are used to the stability of fixed infrastructure, so they struggle dealing with dynamic landforms like river deltas. But rivers changing course and evolving over time is a good sign for the delta and the environment around it. In a new commentary published in Earth’s Future, a national team of experts including Irina Overeem examines the ongoing conflict between stability and sustainability in heavily populated river deltas, such as the Ganges-Brahmaputra-Meghna in India/Bangladesh and Mississippi in the U.S.

Off

Traditional

White