The grape remote sensing atmospheric profile and evapotranspiration experiment

Authors: Kustas, William - Bill; Anderson, Martha; Alfieri, Joseph; Knipper, Kyle; TORRES, A. - Utah State University; Parry, Christopher; NIETO, H. - Institute De Recerca I Tecnologia Agroalimentaries (IRTA); AGAM, N. - Ben Gurion University Of Negev; White, William - Alex; Gao, Feng; McKee, Lynn; Prueger, John; McElrone, Andrew; LOS, S. - Utah State University; ALSINA, M. - E & J Gallo Winery; SANCHEZ, L. - E & J Gallo Winery; SAM, B. - E & J Gallo Winery; DOKOOZLIAN, N. - E & J Gallo Winery; MCKEE, M. - Utah State University; JONES, S. - Utah State University; HIPPS, L.E. - Utah State University; HEITMAN, J. - North Carolina State University; HOWARD, A. - North Carolina State University; POST, K. - California State University; MELTON, F. - Collaborator

Submitted to: Bulletin of the American Meteorological Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2018
Publication Date: 9/18/2018
Citation: Kustas, W.P., Anderson, M.C., Alfieri, J.G., Knipper, K.R., Torres, A., Parry, C.K., Nieto, H., Agam, N., White, W.A., Gao, F.N., McKee, L.G., Prueger, J.H., McElrone, A.J., Los, S., Alsina, M., Sanchez, L., Sam, B., Dokoozlian, N., McKee, M., Jones, S., Hipps, L., Heitman, J., Howard, A., Post, K., Melton, F. 2018. An overview of the Grape Remote sensing Atmospheric Profile and Evapotranspiration eXperiment (GRAPEX). Bulletin of the American Meterological Society. 99(9):1791-1812. https://doi.org/10.1175/BAMS-D-16-0244.1.
DOI: https://doi.org/10.1175/BAMS-D-16-0244.1

Interpretive Summary: As is the case in many parts of the world, agricultural production in California faces the dual challenge of growing demand for limited water resources and increasing interannual variability in rainfall and water availability. As a result, both the state and its agricultural community recognize the need to develop sustainable long-term water management strategies. Currently, the irrigation management decisions for many California crops are based on a combination of in-situ observations of soil moisture, and remote sensing-based methods using crop coefficients that have been tuned for specific crops. Unfortunately, these methods are not sufficiently robust, particularly for high value and uniquely structured canopies such as vineyards and tree orchards. As a result, significant errors in the timing and amount of irrigation relative to crop water needs have led to an over-prescription of irrigation applications. Accurate maps of evapotranspiration (ET) at daily to weekly increments and sub-field spatial resolutions would help both reduce water use and enhance crop quality. This led to a collaboration with the wine industry on a research project called GRAPEX (Grape Remote sensing Atmospheric Profile and Evapotranspiration eXperiment), and has expanded to include personnel from other USDA-ARS labs, NASA, universities, and industry. The ultimate goal of the project is to provide wine grape producers and, in the longer term, fruit and nut orchard growers with the tools to generate high-resolution ET data needed to guide water management decisions. These tools will have the advantage over the current “business as usual” approach to determine water needs by being applicable year-round and by providing water use information with higher spatial and temporal detail. The tools will also differentiate between the water used by the grass cover crop, active early in the growing season, with water uptake by the grapevines themselves. In addition, the project will demonstrate the utility of using very-high resolution imagery collected via Unmanned Aerial Vehicles (UAVs) at critical times during the growing season to assess in-field variability in vine condition and facilitate precision management.

Technical Abstract: Particularly in light of California’s recent multi-year drought, there is a critical need for accurate and timely evapotranspiration (ET) and crop stress information to ensure long-term sustainability of high-value crops. Providing this information requires the development of tools applicable across the continuum from sub-field scales, to improve water management within individual fields, up to watershed and regional scales for assessment of state and county level water resources. High value perennial crops (vineyards and orchards) are major water users and growers will need better tools to improve water use efficiency to remain economically viable and sustainable during periods of prolonged drought. In order to develop these tools, government, university, and industry partners are evaluating a multi-scale remote sensing-based modeling system for application over vineyards. For the 2013 to 2016 growing seasons, the GRAPEX (Grape Remote sensing Atmospheric Profile and Evapotranspiration eXperiment) project has collected micrometeorological and biophysical data within adjacent Pinot noir vineyards in the Central Valley of California. Additionally, each year ground, airborne and satellite remote sensing data were collected during Intensive Observation Periods (IOPs) representing different vine phenological stages. An overview of the measurements and some initial results on the impact of vine canopy architecture on modeling ET and plant stress are presented here. Refinements to the ET modeling system based on GRAPEX are being implemented initially at the field scale for validation and then will be integrated into the regional modeling toolkit for large area assessment.