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.
National Water Census • Colorado River Basin • Evapotranspiration • Snowpack • Water Use • Groundwater Discharge
Evapotranspiration (ET)—the combination of water transpired from plants and water that evaporates from soil or open water bodies—is an important component of the CRB water budget. The USGS National Water Census program has advanced new methods of remote-sensing-based actual ET (ETa) estimation through the development of the Operational Simplified Surface Energy Balance (SSEBop) model (Senay and others, 2013).
The SSEBop ETa model uses land surface temperature (LST) derived from satellite imagery and integrates these data with local weather datasets (for example, net radiation, air temperature, humidity, wind speed, and air pressure) to produce estimates of ETa at the time of each satellite overpass. Time periods between satellite overpasses are interpolated using potential ET data derived from the land-based weather datasets.
Evapotranspiration (ET) mapping at the Landsat spatial resolution (100 m) is essential to fully understand water use and water availability at the field scale. Water use estimates derived in the CRB FAS will be helpful to water planners and managers. These estimates also provide valuable input to water supply prediction models and water-resource management decision support systems.
Key Findings and Results
- First ever basin-wide, 100-m scale ETa estimate was completed for 2010 using Landsat 5 and 7 imagery.
- 528 Landsat 8 images were used to estimate wall-to-wall ET in the Colorado River Basin.
- Estimated 100-m resolution ETa were used to quantify agricultural irrigation consumptive water use at a field-scale and incorporated into a basin-wide water-use compilation.
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: Snowpack Hydrodynamics
Colorado River Basin Focus Area Study: Water Use
Colorado River Basin Focus Area Study: Groundwater discharge to streams
- Overview
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.
National Water Census • Colorado River Basin • Evapotranspiration • Snowpack • Water Use • Groundwater Discharge
Evapotranspiration (ET)—the combination of water transpired from plants and water that evaporates from soil or open water bodies—is an important component of the CRB water budget. The USGS National Water Census program has advanced new methods of remote-sensing-based actual ET (ETa) estimation through the development of the Operational Simplified Surface Energy Balance (SSEBop) model (Senay and others, 2013).
The SSEBop ETa model uses land surface temperature (LST) derived from satellite imagery and integrates these data with local weather datasets (for example, net radiation, air temperature, humidity, wind speed, and air pressure) to produce estimates of ETa at the time of each satellite overpass. Time periods between satellite overpasses are interpolated using potential ET data derived from the land-based weather datasets.
Sources/Usage: Public Domain.Example of SSEBop Eta product: Spatial distribution of (A ) annual evapotranspiration (millimeters per year) and (B ) evapotranspiration (millimeters per day) on the day of satellite overpass (July 6, 2013) in a selected part of the southern Willcox irrigation district in Arizona. Modified from G.B. Senay, USGS, written commun., Oct. 26, 2015. [ETa, actual evapotranspiration; mm, millimeter] Evapotranspiration (ET) mapping at the Landsat spatial resolution (100 m) is essential to fully understand water use and water availability at the field scale. Water use estimates derived in the CRB FAS will be helpful to water planners and managers. These estimates also provide valuable input to water supply prediction models and water-resource management decision support systems.
Key Findings and Results
- First ever basin-wide, 100-m scale ETa estimate was completed for 2010 using Landsat 5 and 7 imagery.
- 528 Landsat 8 images were used to estimate wall-to-wall ET in the Colorado River Basin.
- Estimated 100-m resolution ETa were used to quantify agricultural irrigation consumptive water use at a field-scale and incorporated into a basin-wide water-use compilation.
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: Snowpack Hydrodynamics
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.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