Monitoring Daily Evapotranspiration in California Vineyards Using Landsat 8

Wednesday, 17 December 2014: 5:45 PM
Kathryn A Semmens1, Martha C. Anderson1,2, William P Kustas1, Feng Gao1, Joseph G Alfieri1,3, Lynn McKee1, John H Prueger4, Christopher Hain5 and Carmelo Cammalleri6, (1)Agricultural Research Service Beltsville, Beltsville, MD, United States, (2)USDA ARS, Pendleton, OR, United States, (3)Organization Not Listed, Washington, DC, United States, (4)Natl Soil Tilth Lab, Ames, IA, United States, (5)Earth System Science Interdisciplinary Center, COLLEGE PARK, MD, United States, (6)JRC - IES, Climate Risk Management Unit, Ispra, Italy
In California’s Central Valley, due to competing demands for limited water resources, it is critical to monitor evaporative water loss and crop conditions at both individual field scales and over larger areas in support of water management decisions. This is particularly important for viticulture because grape vines must be maintained under highly controlled conditions in order to maximize production of quality fruit. Thus, regular high resolution temporal monitoring of hundreds of acres is required, a task only efficiently achieved with satellite remote sensing, combining multiple earth observations. In this research, we evaluate the utility of a multi-scale system for monitoring evapotranspiration (ET) and crop water stress applied over two vineyard sites near Lodi, California during the 2013 growing season.

The system employs a data fusion methodology (STARFM: Spatial and Temporal Adaptive Reflective Fusion Model) combined with multi-scale ET modeling (ALEXI: Atmosphere Land Exchange Inverse Model) to compute daily 30 m resolution ET. ALEXI ET fluxes (4 km resolution, daily) are integrated with ET fluxes from Landsat 8 thermal data (30 m resolution, ~16 day) and Moderate Resolution Imaging Spectroradiometer (MODIS) data (1 km resolution, daily). The high spatial resolution Landsat retrievals are then fused with high temporal frequency MODIS data using STARFM to produce daily estimates of crop water use that resolve within field variation in ET for individual vineyards.

Estimates of daily ET generated in two fields of Pinot Noir vines of different maturity agreed well with ground-based flux measurements collected within each field with relative errors of about 15%. Spatial patterns of cumulative ET correspond to yield estimates and indicate areas of variable crop moisture, condition, and yield within the vineyards that could require additional management strategies due to variation in soil type/texture, nutrient conditions and other environmental factors.