New USU Study Highlights Channel Response in Upper Colorado Basin

A new USU study has shed light on how mountain streams in the Upper Colorado Basin respond to the compounded disturbances of wildfire, extreme precipitation and debris flows.

The study, led by Utah Water Research Laboratory graduate student Paxton Ridgway, USU Professor Belize Lane, and a team of researchers from USU, Simon Fraser University, and the U.S. Geological Survey, explored the intricate dynamics that govern river morphology following wildfire, extreme precipitation and debris flows. The team utilized an array of methodologies including repeat field surveys, time-lapse photography, and remote sensing data.

“We were thrilled to perform a multi-year field-intensive study in a fascinating system that has experienced the implications of shifting wildfire and hydrologic regimes in the western US,” Ridgeway said. “This research examines real-world consequences for downstream environments and human infrastructure from the headwaters to the outlet of the Colorado River.”

UWRL doctoral candidate Haley Canham established the hydrologic monitoring equipment following the 2020 Grizzly Creek Fire wildfire, the focal point of the research in a steep mountain stream affected by wildfire, monsoon storms and debris flows throughout Glenwood Canyon, Colorado.

Wildfires, a growing concern due to climate change, increase the likelihood of runoff-generated debris flows. These events can drastically alter river systems, affecting everything from water resources to the structural integrity of bridges and roads. Understanding how rivers process these episodic sediment inputs is vital for effective watershed management and restoration efforts.

The Grizzly Creek Fire, which burned a significant area along the Colorado River, caused notable disruptions including multiple closures of Interstate 70 and impacts on municipal water supplies. The study's findings are particularly relevant for areas like Glenwood Canyon, where critical infrastructure is at risk.

The researchers identified several types of channel changes following post-fire debris flows, ranging from channelized and braided incision into deposits to bank erosion and no change. These variations were correlated with pre-fire channel width, valley width and unit stream power. Interestingly, the study found that channels often showed rapid recovery and narrowing post-disturbance, although sediment deposits remained along the margins.

The study underscores the significant impact of both spring snowmelt and summer monsoon events on channel morphology. It highlights the importance of understanding these dynamics for better prediction and management of downstream effects, which are crucial for infrastructure, water security and aquatic habitats.

The study received funding from the Utah Water Research Laboratory, a USU SEED grant, and the National Science Foundation. With continued collaboration from the Colorado Department of Transportation, USGS Landslides Hazard Group, and other partners in the region, this research highlights the benefits of interdisciplinary effort needed to address these complex environmental challenges.

For more detailed information, the full study is available in the latest issue of Earth Surface Processes and Landforms and can be accessed here.