SANTA CRUZ – It’s a bird! It’s a plane! This is actually an electromagnetic survey of an aquifer from the air.
From Sunday through Nov. 17, the California Department of Water Resources announced it will conduct several surveys of groundwater basins along the state’s coast — including regions in Santa Cruz County — using innovative, helicopter-based technology.
The effort will create a map of coastal groundwater aquifers, many of which are critically overstressed, meaning groundwater is being withdrawn from the basin at a faster rate than it is being replenished through natural precipitation. This can lead to a variety of water problems, including seawater intrusion, which can seep into freshwater wells and contaminate them when water levels are low.
The studies are part of the Sustainable Groundwater Management Act, a 2014 bill aimed at setting a statewide framework for protecting groundwater resources over the long term in the face of continued drought conditions.
“The data collected during these studies will provide a better understanding of California’s groundwater systems and, in turn, support more informed and sustainable groundwater management and drought preparedness and response approaches,” said Stephen Springhorn, the Department of Water Resources’ technical assistance manager for the draft bill.
The helicopters will tow a large hoop about 100 feet in the air, which is equipped with electronic equipment that sends signals to the ground, according to the release. The signals, which can penetrate to a depth of approximately 1,000 feet below the surface, are beamed back to the devices, creating an image of the pools and their condition—a process similar to an MRI.
The San Lorenzo Valley, Pajaro Valley and Mid-County regions are among the state’s priority mapping areas because they have significant populations that rely on groundwater basins threatened by seawater intrusion.
“This (seawater intrusion) is an ongoing problem that occurs in the Pajaro Valley and other coastal basins,” Pajaro Valley Water Management Agency Associate Hydrologist Casey Meusel told the Sentinel.
Meusel said that while the South County agency can monitor water data through individual wells, mapping from the state survey will help put the pieces of the puzzle together for a more complete picture.
“With these continuous flight lines and the depths that can be detected, it will give us a more comprehensive estimate in a short amount of time of where seawater intrusion is occurring,” Meusel said. “These studies will provide more permanent information.”
Ron Duncan is the general manager of the Soquel Creek Water District and said he previously led airborne electromagnetic surveys in offshore regions to get a broad picture of the extent of penetration. He said he’s glad to see the state use such tactics.
“I think the state is so smart to take this innovative approach with the helicopter,” Duncan said. “It can map all the aquifers, and they can tell where the water is, how deep it is, and where there’s good geology to store water.”
Duncan said aerial photography is extremely cost-effective and land mapping in particular will help supplement the data for his area.
“We’ve drilled wells in areas and you’re logging the geology as you go down,” Duncan said, “but this will see it in a more three-dimensional model.”
According to the state agency’s release, the airborne electromagnetic method is safe and has been used successfully previously in regions throughout California.
Surveys will only be conducted during daylight hours and the helicopter will not fly over businesses, homes, other inhabited structures or closed animal feeding operations. Meusel and Duncan told the Sentinel the effort is state-funded and no local contributions are required.