Valley residents may see something rather unusual in the sky this month.
Beginning Monday, a low-flying helicopter equipped with a large hexagonal frame will survey the sky as part of a project to map out the aquifers and improve the county’s understanding of groundwater in the area. The flights are scheduled to occur for five to seven days, though the flight period may be extended, according to county officials.
The project is being conducted by the county in partnership with the Santa Ynez River Water Conservation District and other local water agencies that comprise the three Groundwater Sustainability Agencies in the Santa Ynez River Valley Groundwater Basin.
During the Aerial Electromagnetic Method survey, instruments suspended approximately 100 feet above the ground use an electromagnetic signal to measure the subsurface. The signal interacts with the geologic materials below the ground, stimulates a response from those materials, and generates another signal that is picked up by receivers, according to Matt Young, water resources program manager for the county Public Works Department.
The technology allows for fast data acquisition from the air. Data are continually acquired while the helicopter makes its 600-mile flight between 50 to 75 mph. This process produces images that reveal the detailed variation in the earth’s electrical properties, down to 1,000 feet below the land surface. When combined with well data and knowledge of the geology, these data will refine understanding — in three dimensions — of the geographic extent of sands, gravels, and clays that make up the aquifers of the regional groundwater system.
A number of protocols are in place to ensure the safety of the project.
The airborne geophysical survey will be conducted by pilots who are specially trained for low-level flying. The helicopter will not fly over businesses, homes, other inhabitable structures, or confined animal feeding operations, officials said.
The intensity of the magnetic field generated by the AEM transmitter is below 1% of the accepted general public exposure level. At 60 hertz, the magnetic field experienced by standing next to the transmitter is the same as standing one foot away from a toaster. Similar AEM surveys have been conducted throughout California with no reported ill effects to humans or animals.
For more information, visit www.santaynezwater.org/aem-survey-ema for up-to-date information.