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EVALUATING REGIONAL REFERENCE EVAPOTRANSPIRATION WITH ATMOMETERS AND MODELED VALUES UNA EVALUACION DE LA EVAPOTRANSPIRACION DE REFERENCIA CON ATMOMETROS Y VALORES DE MODELOS
BATTANY, Mark University of California Cooperative Extension; 2156 Sierra Way, Suite C; San Luis Obispo, California, 93401 USA Corresponding author: mcbattany@ucanr.edu
Abstract: The irrigated vineyards of the Paso Robles region of California depend upon groundwater for irrigation; this groundwater supply is currently impacted by excessive withdrawals. More detailed information on regional reference evapotranspiration (ETo) will be important to improve irrigation management the region. The ETo data generated by the Spatial CIMIS program of the California Department of Water Resources has the potential to be a useful ETo source for this region. The purpose of this study was to evaluate regional ETo during the summer irrigation season using evaporating atmometers, and to compare these values to the values produced by the Spatial CIMIS program. Atmometers were installed at 18 irrigated vineyard locations over the groundwater basin east of Paso Robles during the 2013 and 2014 growing seasons. The daily total ETo produced by the atmometers was compared to the daily ETo values produced by the Spatial CIMIS program. The two entirely independent methods produced similar overall results; in 2013, the daily average atmometer ETo was 6.1 mm-d-1, while the Spatial CIMIS ETo was 6.3 mm-1. In 2014 the values were 5.6 mm-d-1 and 6.1 mm-d-1 respectively. These results support the use of the Spatial CIMIS ETo values in this region as a component of climate-based irrigation scheduling.
Keywords: Reference evapotranspiration, ETo, atmometer, CIMIS
Abstract: The irrigated vineyards of the Paso Robles region of California depend upon groundwater for irrigation; this groundwater supply is currently impacted by excessive withdrawals. More detailed information on regional reference evapotranspiration (ETo) will be important to improve irrigation management the region. The ETo data generated by the Spatial CIMIS program of the California Department of Water Resources has the potential to be a useful ETo source for this region. The purpose of this study was to evaluate regional ETo during the summer irrigation season using evaporating atmometers, and to compare these values to the values produced by the Spatial CIMIS program. Atmometers were installed at 18 irrigated vineyard locations over the groundwater basin east of Paso Robles during the 2013 and 2014 growing seasons. The daily total ETo produced by the atmometers was compared to the daily ETo values produced by the Spatial CIMIS program. The two entirely independent methods produced similar overall results; in 2013, the daily average atmometer ETo was 6.1 mm-d-1, while the Spatial CIMIS ETo was 6.3 mm-1. In 2014 the values were 5.6 mm-d-1 and 6.1 mm-d-1 respectively. These results support the use of the Spatial CIMIS ETo values in this region as a component of climate-based irrigation scheduling.
Keywords: Reference evapotranspiration, ETo, atmometer, CIMIS