Comparison of Eddy Covariance Evapotranspiration Measurements to DSSAT and Remote Sensing Based Simulations in Dryland Cotton in East-Central Texas

Accurate simulations of evapotranspiration (ET) are important in quantifying the contributions of agroecosystems to global hydrologic cycles. The objective of this study is to model ET using the Decision Support System for Agrotechnology Transfer (DSSAT) crop growth model and a Satellite remote sensing based model. Eddy Covariance was used to make measurements of ET in a dryland cotton (Gossypium hirstum L.) field in Burleson County, TX in the 2017 and 2018 growing seasons. These measurements were made using an open-path eddy covariance system consisting of a CSAT-3A sonic anemometer (Campbell Scientific Inc., Logan, UT, USA) and LI-7500A infrared gas analyzer (LI-COR Biosciences, Lincoln, NE, USA). Using the eddy covariance method, half-hourly flux of latent heat (LE) was calculated and then converted to ET in millimeters. Supporting meteorological and plant phenological data were also collected. The DSSAT- Cropping System Models (CSM) for cotton (CROPGRO plant growth module) was calibrated using plant phenological data. After calibration, model simulations of ET were compared with actual field measurements. The remote sensing model was constructed using satellite images from Planetscope, a high resolution imaging satellite network, and collected LAI and PAR data. Statistical analysis and graphing was performed using Sigma Plot 13.0. Results from this project will be presented at the meeting.