Assessment of Landsat-based evapotranspiration using weighing lysimeters in the Texas High Plains

Authors: HASHEM, AHMED - Arkansas State University; ENGEL, BERNARD - Purdue University; BRALTS, VINCENT - Purdue University; Marek, Gary; MOORHEAD, JERRY - Lindsay Corporation; RADWAN, SHERIF - Suez Canal University; Gowda, Prasanna

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2020
Publication Date: 10/30/2020
Citation: Hashem, A.A., Engel, B.A., Bralts, V.F., Marek, G.W., Moorhead, J.E., Radwan, S., Gowda, P.H. 2020. Assessment of Landsat-based evapotranspiration using weighing lysimeters in the Texas High Plains. Agronomy. 10(11). Article 1688. https://doi.org/10.3390/agronomy10111688.
DOI: https://doi.org/10.3390/agronomy10111688

Interpretive Summary: Accurate estimation of evapotranspiration (ET) is paramount for effective irrigation scheduling in semi-arid regions to conserve limited water resources. However, acquiring accurate field measurements of ET can be challenging. Equipment and data processing resources can be considerable for field-scale measurements while lending little insight into the spatial variability of ET. The estimation of ET using satellite remote sensed data aims to alleviate the limitations of field-based ET estimation. However, satellite-based ET estimation software programs and models require measured data for evaluation and validation. Researchers from Arkansas State University, Purdue University, Suez Canal University, and USDA-ARS compared daily, monthly, and seasonal satellite-based estimates of ET with 10 years of measured ET data from large weighing lysimeters at the USDA-ARS Conservation and Production Research Laboratory in Bushland, TX. Results indicated that although satellite-based estimates were deemed acceptable for fully irrigated fields, results for dryland managed crops were considered poor, having overestimated ET.

Technical Abstract: Evapotranspiration (ET) is one of the largest data gaps in water management, due to limited availability of observed evapotranspiration data, and further, spatial variability of ET is difficult to characterize. Satellite-based ET estimation has been shown to have great potential for water resources planning as well as estimating agricultural water use at field, regional, and watershed scales. Satellites with low spatial resolution, such as NASA’s MODIS (Moderate Resolution Imaging Spectroradiometer), and those with higher spatial resolution, such as Landsat (Land Satellite), can be used for irrigation water management purposes and other agricultural applications. This study was performed at the USDA-ARS Conservation and Production Research Laboratory (CPRL) in Bushland, Texas, to assess satellite based-ET estimation accuracy using observed ET using large weighing lysimeters. Daily, 7-day running average, monthly, and seasonal satellite based-ET data were compared with corresponding lysimeter ET data. Hourly comparisons of ET, surface temperature, net radiation and soil heat flux were also performed. The daily Landsat ET estimates were characterized as good for irrigated fields and poor for the dryland managed fields.