Dreaming of a White Christmas
Increasing Temperatures, Changing Precipitation Patterns in Colorado River Basin Mean Less Water Downstream
Increased temperatures in the Colorado River Basin have affected the basin’s streamflow — further evidence that climate change is impacting water resources in our region, a new UNLV study shows.
The ability to forecast water flow into the Colorado River is important to water resource managers, who need accurate forecasts to plan both annual and long-term system operations.
More frequent rainfall and less frequent snowfall over the last 55 years has led to less snowpack and snowmelt in the region.
"Snowfall, particularly in the upper part of the basin, is important as it replenishes mountain storage and is a key runoff source during the spring," said Tom Piechota, UNLV director of sustainability and multidisciplinary research and professor in civil and environmental engineering. "When rain occurs in place of snow, streamflow peaks earlier in the year and can make it challenging for water managers to assess resource availability."
Decreased River Flows
Using historical temperature and precipitation data and records of natural runoff, researchers identified a consistent increase in temperatures in the basin, increased river flows in the late fall and winter months, and decreased river flows during the peak runoff season (April through July).
The study does not explicitly compare trends in snowpack with streamflow trends. Researchers, believe, however, that rising temperatures have resulted in increased rainfall frequency and earlier snowmelt.
The Colorado River Basin includes portions of seven states — Colorado, Wyoming, Utah, New Mexico, California, Nevada, and Arizona — and encompasses approximately 242,900 square miles. Runoff from snowmelt in the high mountains in the upper part of the basin is the primary water supply source for the Colorado River.
Researchers and Funding
The study appeared in the October 2008 issue of Journal of Hydrometeorology. Piechota conducted the study with W. Paul Miller, a UNLV graduate student and hydrologic engineer student trainee with the federal Bureau of Reclamation in Boulder City, Nev.
Funding came from:
- Bureau of Reclamation
- National Science Foundation
- National Oceanic and Atmospheric Administration
Related Information
Tom Piechota
UNLV Urban Sustainability Initiative
Civil and Environmental Engineering
Journal of Hydrometerology
