ITRC uses a modified Mapping of EvapoTranspiration with Internal Calibration (METRICTM) procedure to compute actual evapotranspiration using LandSAT Thematic Mapper data. The original METRIC procedure was developed by Dr. Richard Allen (University of Idaho). ITRC has made a number of modifications to the original procedures including using a grass reference evapotranspiration instead of alfalfa, a semi-automated calibration procedure, spatially interpolated ETo, modifications to the aerodynamic resistance and albedo computations for certain crops, etc.
The ITRC-METRIC process is based on a surface energy balance and includes corrections for aerodynamic resistance. It depends upon both accurate and frequent LandSAT satellite thermal images and understanding of the cropping systems within a region. The METRIC programs have gradually evolved from research in the US and other countries with the objective of being able to directly estimate actual ET over large areas with limited data availability (such as crop type, irrigation method, irrigation practices, etc.).
Click on the image to the right for a visual summary of the technique.
- ITRC Report No. R 04-001: Integrating Remote Sensing of Evapotranspiration with Applied Water to Target Potential Water Conservation Projects in Watersheds
- ITRC Paper No. P 15-002: Evapotranspiration from Natural Vegetation in the Central Valley of California: Monthly Grass Reference-Based Vegetation Coefficients and the Dual Crop Coefficient Approach
- ITRC Paper No. P 15-001: Center Pivot Sprinkler Distribution Uniformity Impacts on the Spatial Variability of Evapotranspiration
- ITRC Paper No. P 14-005: Evaluating Net Groundwater Use from Remotely Sensed Evapotranspiration and Water Delivery Information
- ITRC Paper No. P 14-003: Grass Referenced Based Vegetation Coefficients for Estimating Evapotranspiration for a Variety of Natural Vegetation
- ITRC Paper No. P 12-003: Comparison of Field Level and Regional Actual ETc Values Developed from Remote Sensing and Dual Crop Coefficient Procedure
- ITRC Paper No. P 12-002: Basin-Wide Remote Sensing of Actual Evapotranspiration and its Influence on Regional Water Resources Planning
- ITRC Paper No. P 12-001: Spatial Variability in Evapotranspiration Related to Irrigation System Distribution Uniformity