University of California Cooperative Extension (UCCE) scientists want to put concrete numbers to estimates of how much water vineyards use.

Currently, local entities created under the Sustainable Groundwater Management Act estimate the total volume applied to vines by looking at models, say University of California advisors in Sonoma County.

However, the models don’t consider site variability and the deficit irrigation practices put in place by many growers.

So the university is looking for growers in the northern San Francisco Bay area to help measure actual water volume applied in individual blocks with the use of a pressure switch plumbed into a single irrigation drip line, the researchers explain in a news release.

In the so-called “hands-off” study, a data logger records the irrigation run time and will be downloaded at the end of four years and information about each property will be destroyed, thus insuring the anonymity of participants, the release assures.

A similar survey was done on 84 blocks in Paso Robles, which informed the vineyard irrigation component of the Paso Robles Groundwater Basin model. The project is discussed in the journal California Agriculture.

“Accurate information on irrigation water usage does not exist in many areas where groundwater is the primary water source,” scientists Mark Battany and Gwen Tindula wrote. “This lack of information will hinder efforts to manage these groundwater basins sustainably according to current and future water regulations and policies.”

Battany is a water management and biometeorology advisor for San Luis Obispo and Santa Barbara counties. He and Rhonda Smith, a viticulture advisor in Sonoma County, received funding for the project from the American Vineyard Foundation.

The next study area

Specifically, Smith would like to hear from growers inside the three mapped groundwater basins in Sonoma County that are designated as medium priority by the California Department of Water Resources. They are Santa Rosa Plain, Petaluma Valley and Sonoma Valley.

The UCCE would also like to study the Alexander Valley groundwater basin, which is not currently designated as medium priority, according to the release.

Ideally, Smith would like to see 30 sites identified in each basin as committed to participating, she said in her release. The office planned on purchasing equipment this month and installing it over the winter.

Participants will have a single sensor-logger unit installed by UCCE. The units will be removed after the 2023 season.

“The methodology also could be utilized in other regions to estimate regional irrigation usage while maintaining anonymity for participants,” Battany and Tindula wrote.

To participate in the Sonoma County study, email a map of blocks in your vineyard that receive applied water through a drip system to Smith at [email protected]. For information, call (707) 565-2621.

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