The Colorado River system is a crucial water source for 40 million people in the United States and Mexico, but it is now facing a severe crisis due to prolonged drought and overuse.
The demand for water far exceeds the available supply, putting immense pressure on this vital resource.
Almost all of the water in the 1,450-mile-long river originates from snowmelt in the Upper Colorado River Basin.
This region, adjacent to arid landscapes, is susceptible to dust storms that can significantly affect the river’s snowpack.
Dust deposition on mountain snowpacks darkens the snow surface, leading to increased absorption of sunlight, which accelerates melting and depletes snowpacks earlier than expected.
As a result, downstream communities face an increased risk of running dry.
Currently, no snowmelt models account for the impact of dust, which presents a major challenge for water managers who depend on accurate estimates for water allocation.
In response to this critical issue, a team led by the University of Utah has released a groundbreaking remote-sensing dataset that provides insights into the timing and magnitude of snow darkening and its effects on melt rates across the Colorado Basin.
This research marks the first comprehensive evaluation of how dust impacts the extensive headwaters contributing to the Colorado River system.
The authors undertook an extensive analysis of 23 years of daily satellite images to identify patterns of snow darkened by dust during the melt season of April and May from 2001 to 2023.
The findings revealed that dust-driven melting peaks earlier and is most intense in the central and southern Rocky Mountains at mid-alpine elevations.
The study found that dust consistently accelerated snowmelt each spring, even during less dusty years.
Spring melt rates, typically measured at observation sites, average around 10 to 15 millimeters per day.
However, this new research discovered that dust deposition can enhance snowmelt by up to 1 millimeter water-equivalent per hour at peak sunlight.
In high-dust years, this phenomenon can result in an additional 10 millimeters of melt per day attributed directly to the darkening effect.
Patrick Naple, a Ph.D. candidate at the University of Utah and the lead author of the study, emphasized the importance of both the amount and timing of dust deposition.
“Dust is very effective at speeding up melt because it’s most frequently deposited in the spring, when days are getting longer and the sun more intense,” said Naple.
“Even an extra millimeter per hour can make the snowpack disappear several weeks earlier than without dust deposition.”
As the most thorough assessment of dust-driven snowmelt to date, the study’s findings hold the potential to improve the understanding of dust impacts across the entire Colorado River Basin.
This enhanced knowledge could ultimately lead to better forecasting and more informed water allocation strategies in a region grappling with the pressures of changing climate patterns and growing populations.
“The degree of darkening caused by dust has been related to water forecasting errors,” noted McKenzie Skiles, associate professor at the University of Utah and co-lead author of the study.
“Water can arrive earlier than expected, impacting actual use.
For instance, if the ground is still frozen, farmers may not already be able to utilize the water.
Reservoir managers can store early snowmelt, but they need the right information to plan accordingly.”
The research aims to incorporate dust factors into snowmelt forecast models, enabling more informed decisions for water management.
The study, published in Geophysical Research Letters on March 9, 2025, highlights the environmental processes contributing to the current water crisis in the Colorado River Basin.
Seasonal spring storms deposit rich, red dust from the Colorado Plateau, transporting it miles away before it lands on mountain slopes and snowpack.
The dust darkens the usual bright surface of the snow, which leads to rapid melting.
Previous studies have documented dust-driven melting at specific locations, but none have assessed its wide-ranging effects across the expansive headwaters of the Colorado River that span multiple states.
To elevate their research, the authors built upon a concept developed by Skiles and her colleagues in 2012, which utilized satellites to remotely quantify snow darkening.
They relied on the Moderate Resolution Imaging Spectrometer (MODIS) instrument on the Terra satellite, which captures multiple wavelengths of solar radiation reflected from the Earth’s surface on a daily basis.
This technology allowed them to create detailed maps illustrating land-surface characteristics.
The researchers focused on assessing the amount of sunlight energy reflected by various surfaces, a property known as albedo.
A brighter surface has a higher albedo and reflects more energy, while a darker surface has a lower albedo and absorbs more energy.
Out of all land cover types, snow naturally has the highest albedo, rendering it particularly susceptible to dust deposition effects.
The authors devised algorithms that quantified the manner in which dust reduces albedo at every pixel of satellite imagery, and calculated how this change in energy absorption influenced melt rates.
The data provided some unexpected outcomes.
During the latter part of the study period from 2014 to 2021, there were slightly lower levels of dust-driven melting than in the earlier period from 2001 to 2013.
This was surprising to researchers, especially given that the western U.S. has been experiencing a persistent drought, making the region increasingly arid over the past few decades.
“Intuitively, you’d think that if the soil is drier, there’s going to be more dust emissions, but that’s not what we saw,” said Naple.
The occurrences of consequential dust-on-snow events depend on a variety of factors such as wind speed, soil moisture, vegetation, surface disturbance, and precipitation timing, all of which collectively determine how much dust is picked up and transported.
While the results are not definitive, the authors suspect that increased vegetation and lower wind speeds in dust-source regions may influence the levels of dust observed, based on research conducted by their colleagues.
The factors contributing to diminished dust impacts might be linked to climate variability, but the short 20-year timescale is likely insufficient to capture broader climate patterns.
Skiles noted, “We can use remote sensing data to get a real-time estimate of how any specific dust event is impacting snow cover, but it doesn’t provide much lead time because we don’t know ahead of time when a significant dust event will occur.
If we can understand the drivers of dust emission better, we could potentially predict how that will affect snow for the rest of the season.”
Further research is essential in linking land-use changes, climate-scale variability, and other major factors that influence dust emissions and their transport.
Skiles pointed out that evidence from sediment core records indicates that dust deposition in this region surged dramatically following the settlement of the West, which confirms that contemporary levels of dust are directly connected to human activity.
“By tracking ongoing land-use changes and surface disturbances in the area, we might ultimately improve our ability to predict large dust episodes,” Skiles remarked in conclusion.
image source from：https://attheu.utah.edu/facultystaff/major-dust-up-for-water-in-the-colorado-river/
