At a Glance
- The Colorado River and its tributaries are vital for hydropower, irrigation, and drinking water across seven U.S. states and Mexico. Much of the water supply is dependent on melting snow.
- Since 2000, water flow predictions based on snowpack data have consistently fallen short, with actual water flow being lower than forecasted.
- New research attributes nearly 70% of the discrepancy between predicted and actual water flow to reduced spring rainfall, which decreases water reaching streams.
- Reduced rainfall leads to increased plant growth and water evaporation, with sublimation (snow turning directly into vapor) accounting for only 10% of the missing water.
- The study underscores the importance of accurate spring precipitation forecasts for better water management in the Colorado River Basin, especially amid the ongoing Millennium drought.
The Colorado River and its tributaries provide essential water for hydropower, irrigation, and drinking in seven U.S. states and Mexico. Much of this water comes from melting snow, which is crucial for predicting water availability yearly. However, since 2000, predictions based on snowpack data have been consistently inaccurate, with actual water flow falling short of forecasts. Researchers have identified a key factor contributing to this discrepancy: reduced spring rainfall.
New research from the University of Washington reveals that drier springs are primarily to blame for the lower water flow. The study found that decreased rainfall during spring accounts for almost 70% of the gap between predicted and actual water flow. Without sufficient rain, plants in the region rely more heavily on snowmelt, reducing the amount of water that reaches streams. Additionally, less rain leads to sunnier conditions, increasing plant growth and water evaporation from the soil.
The researchers, including doctoral student Daniel Hogan and professor Jessica Lundquist, published their findings on August 16 in Geophysical Research Letters. They discovered that while some of the missing water could be attributed to a process called sublimation—where snow turns directly into water vapor—this only accounted for 10% of the deficit. The remaining water loss is mainly due to reduced spring precipitation and increased evaporation rates.
The study emphasizes the need for more accurate spring precipitation forecasts to improve water predictions. As the Millennium drought continues, understanding how spring rainfall affects water availability is crucial for managing resources in the Colorado River Basin. Future research will explore whether snow patches act as mini-reservoirs to provide a steady water supply to plants, potentially helping to mitigate the impacts of ongoing drought conditions.
References
- Hogan, D., & Lundquist, J. D. (2024). Recent Upper Colorado River Streamflow Declines Driven by Loss of Spring Precipitation. Geophysical Research Letters, 51(16), e2024GL109826. https://doi.org/10.1029/2024GL109826
- University of Washington. (2024, August 16). Why isn’t Colorado’s snowpack ending up in the Colorado River? Research suggests it might be the lack of spring rainfall. Phys.Org; University of Washington. https://phys.org/news/2024-08-isnt-colorado-snowpack-river-lack.html
