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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Water Management and Systems Research » Research » Research Project #438604

Research Project: Calibration and Evaluation of a Multi-Scale Spatially Distributed Evapotranspiration (ET) Algorithm

Location: Water Management and Systems Research

Project Number: 3012-13000-010-16-N
Project Type: Non-Funded Cooperative Agreement

Start Date: Sep 1, 2020
End Date: Aug 30, 2023

Objective:
Long-term goals of this cooperative research project between USDA-ARS and Cooperator are: 1) to evaluate the effect of different remote sensing (RS) pixel spatial resolutions (scales) on the estimation of different types of data needed for estimating crop evapotranspiration (ETa) on hourly, daily and weekly time frames, 2) to develop a calibration protocol and standards for the (seamless) use of different imagery spatial resolutions (scales) in RS of ETa algorithms, and 3) to determine the accuracy of calibrated/standardized imagery and resulting ETa rates (from selected RS of ETa algorithms) on irrigation decisions in experimental fields.

Approach:
The Cooperator and USDA-ARS scientists will work closely together to design research and conduct field experiments at the USDA-ARS Limited Irrigation Research Farm (LIFR) and CSU Arkansas Valley Research Center (AVRC) lysimeter fields in Rocky Ford. During the first year of the project, existing remote sensing (RS) data will be used to estimate crop biophysical characteristics and ETa rates at different spatial resolutions. Once the optimal RS pixel size has been identified for a given RS of ETa method, we are going to develop a protocol to scale RS imagery acquired at non-optimal pixel size(s) to that pixel spatial resolution (size) optimal to the given ETa method of interest in the second year. During the third year, using remote sensing and ground based data collected at LIRF and AVRC during the project second year, three selected different RS of ETa algorithms will be applied with the optimized pixel scaling procedure (using data from different spatial scales) determined in Objective 2. Crop height, leaf area index, percent cover, transpiration and evapotranspiration products will be evaluated with field measured or derived data. The overall performance of the scaling algorithm(s) and RS of ETa approach will be determined (accuracy/error) using statistical analysis.