The Focus Area Study examined factors affecting snowpack distribution, snowmelt, and losses of snowpack water due to sublimation in the Upper Colorado River Basin. Also, as part of the FAS, the USGS has developed methods to make physical measurements of snowpack sublimation.
National Water Census • Colorado River Basin • Evapotranspiration • Snowpack • Water Use • Groundwater Discharge
Understanding the spatial distribution of snowpack water content is essential for forecasting annual runoff in the Upper Colorado River Basin (UCRB). As part of the Colorado River Basin Focus Area Study (CRB FAS), the USGS conducted studies of factors affecting snowpack distribution, snowmelt, and losses of snowpack water due to sublimation in the UCRB.
The USGS has compared the output from the National Weather Service’s Snow Data Assimilation (SNODAS) program (National Operational Hydrologic Remote Sensing Center, 2004) to field-based measurements at multiple locations in the UCRB. Additionally, the USGS installed stations for making physical measurements of snow sublimation and developed spatially distributed estimates of sublimation using a physically-based snow model. Lastly, long-term trends of dust deposition in the Rocky Mountains were evaluated using USGS snow chemistry network observations and were used to evaluate the drivers of changing snowmelt timing.
Results of these studies and ongoing work will help improve runoff forecast models used by water managers in the Western United States.
Key Findings and Results
- Peak snow water equivalent (SWE) in Colorado is occurring 2–3 weeks earlier than it did during the late 1970s, and snowmelt timing has accelerated 7–18 days from 1993 - 2014 primarily due to changes in snowfall and dust deposition.
- Continuous measurements of snow sublimation at multiple sites were developed and indicate a seasonal loss of 2–30 percent of annual SWE, depending on a variety of conditions including land cover, elevation, aspect, temperature, and wind speed.
- A spatially distributed snow model simulated sublimation losses to the atmosphere equivalent to 28% of winter precipitation and highlighted that the highest relative sublimation fluxes occurred during the lowest snow years.
National Water Census • Colorado River Basin • Evapotranspiration • Snowpack • Water Use • Groundwater Discharge
Below are related science components of the Colorado River Basin Focus Area Study.
Colorado River Basin Focus Area Study
Colorado River Basin Focus Area Study: Evapotranspiration
Colorado River Basin Focus Area Study: Water Use
Colorado River Basin Focus Area Study: Groundwater discharge to streams
- Overview
The Focus Area Study examined factors affecting snowpack distribution, snowmelt, and losses of snowpack water due to sublimation in the Upper Colorado River Basin. Also, as part of the FAS, the USGS has developed methods to make physical measurements of snowpack sublimation.
National Water Census • Colorado River Basin • Evapotranspiration • Snowpack • Water Use • Groundwater Discharge
Sources/Usage: Public Domain.Meteorological and continuous sublimation monitoring station, Upper Colorado River Basin (Credit: David Clow, USGS) Understanding the spatial distribution of snowpack water content is essential for forecasting annual runoff in the Upper Colorado River Basin (UCRB). As part of the Colorado River Basin Focus Area Study (CRB FAS), the USGS conducted studies of factors affecting snowpack distribution, snowmelt, and losses of snowpack water due to sublimation in the UCRB.
The USGS has compared the output from the National Weather Service’s Snow Data Assimilation (SNODAS) program (National Operational Hydrologic Remote Sensing Center, 2004) to field-based measurements at multiple locations in the UCRB. Additionally, the USGS installed stations for making physical measurements of snow sublimation and developed spatially distributed estimates of sublimation using a physically-based snow model. Lastly, long-term trends of dust deposition in the Rocky Mountains were evaluated using USGS snow chemistry network observations and were used to evaluate the drivers of changing snowmelt timing.
Results of these studies and ongoing work will help improve runoff forecast models used by water managers in the Western United States.
Key Findings and Results
- Peak snow water equivalent (SWE) in Colorado is occurring 2–3 weeks earlier than it did during the late 1970s, and snowmelt timing has accelerated 7–18 days from 1993 - 2014 primarily due to changes in snowfall and dust deposition.
- Continuous measurements of snow sublimation at multiple sites were developed and indicate a seasonal loss of 2–30 percent of annual SWE, depending on a variety of conditions including land cover, elevation, aspect, temperature, and wind speed.
- A spatially distributed snow model simulated sublimation losses to the atmosphere equivalent to 28% of winter precipitation and highlighted that the highest relative sublimation fluxes occurred during the lowest snow years.
National Water Census • Colorado River Basin • Evapotranspiration • Snowpack • Water Use • Groundwater Discharge
- Science
Below are related science components of the Colorado River Basin Focus Area Study.
Colorado River Basin Focus Area Study
As one of several Focus Area Studies within the USGS National Water Census (NWC), the USGS has completed a 3-year study of water availability and use in the Colorado River Basin.Colorado River Basin Focus Area Study: Evapotranspiration
New USGS-developed, remote-sensing based approaches were used to quantify agricultural irrigation water consumption on a field-by-field scale. The work produced the first ever Colorado River Basin-wide, 100-m scale actual ET estimate (2010) using Landsat imagery.Colorado River Basin Focus Area Study: Water Use
Water-use data were compiled as annual total withdrawals by source and aggregated to 8-digit Hydrologic Unit Code watersheds from 1985 to 2010 in five year intervals. The new compilation allows for an evaluation of water-use trends in the Colorado River Basin and the effect of use on the water budget.Colorado River Basin Focus Area Study: Groundwater discharge to streams
Methods were developed in the CRB FAS to estimate groundwater discharge to streams in the upper Colorado River Basin (UCBR) using in-stream water-quality data. Results indicate groundwater discharge to streams contributes an average of 48 percent of total streamflow in the UCRB. - Publications