Low-Flying Helicopters Will Map Southwest Michigan's Groundwater Using Advanced Geophysical Technology

Southwest Michigan residents may soon notice helicopters carrying large sensor hoops flying overhead as part of a groundbreaking collaboration between the U.S. Geological Survey and the Michigan Department of Environment, Great Lakes, and Energy (EGLE) to study groundwater resources across the region.

The four-month electromagnetic survey will create detailed 3-D maps of Southwest Michigan's groundwater reserves to depths of more than 1,000 feet underground, according to EGLE officials. The study will cover Berrien, Cass, and Van Buren counties, with broader plans to include additional counties in the Southwest Michigan region.

How the Technology Works

The helicopters will be towing large hexagonal sensor hoops that hang about 100 to 200 feet below the aircraft. As the helicopters fly at relatively low altitudes—several hundred feet above ground—electromagnetic sensors attached to the hoop measure the electrical resistivity of the subsurface.

"The helicopter tows a large—it looks like a hula hoop, but it's really large and it has these electromagnetic sensors attached to the hoop," said Sydney Ruhala, EGLE Groundwater Data Unit Supervisor. "And the helicopter will fly at relatively low altitudes, several hundreds of feet above the ground surface."

As the helicopters pass over, electronic signals bounce back to the choppers, allowing researchers to see what lies beneath the ground. The technology measures electrical resistivity to determine what types of materials exist below ground surface—including sands, gravels, clays, and bedrock.

"Essentially what it does is it's measuring what's called the electrical resistivity of the subsurface. So it can tell us, when you look at the resistivity, it can tell us about the types of materials beneath the ground surface," Ruhala explained. "So whether you have sands and gravels, or if you have clays. It can also tell you about the bedrock, so the consolidated rock material that you have underground."

The resulting data will create a three-dimensional map of the subsurface that researchers will use to study groundwater resources across the region.

Why This Matters for Michiganders

Michigan residents—approximately 40% of the state's population—rely on groundwater for drinking water, according to Ruhala. Groundwater is also critical for numerous industries, including irrigation for agriculture and non-contact cooling water for industrial applications.

"Groundwater is also important in the water cycle. It connects to our surface water bodies so it's important for our ecosystems," Ruhala said.

Southwest Michigan was specifically chosen for this survey due to several factors: large-quantity water withdrawals, rapid population growth, and existing groundwater availability issues. The area also includes the Dowagiac River watershed and tribal lands of the Pokagon Band of Potawatomi and the Match-E-Be-Nash-She-Wish Band of Potawatomi.

"Denser data will be collected over the Dowagiac River watershed and around the tribal lands of the Pokagon Band of Potawatomi and the Match-E-Be-Nash-She-Wish Band of Potawatomi, along with the river corridors of the Kalamazoo, Thornapple, St. Joseph, Paw Paw, and Rocky rivers," according to WZZM-TV.

Safety and Public Impact

The flights will avoid densely populated areas and will not pass over buildings at low altitude. The equipment is safe for plants, animals, and humans, according to EGLE officials.

"You'll probably see them overhead flying in their path. They won't make large circles or anything like that. They're pretty much straight lines that they follow. They'll do their best to avoid flying over people, areas with lots of animals, things like that," Ruhala said. "The technology is safe. It does not cause any harm to plants or animals or humans. It's safe technology."

The helicopters will fly in a grid pattern, covering areas systematically while avoiding residential zones.

Previous Surveys and Future Plans

This isn't the first time the U.S. Geological Survey has conducted this type of surveying in Michigan. Ruhala noted that the USGS recently completed similar surveys in Kalamazoo and the Upper Peninsula.

The Southwest Michigan surveys will begin around the second week of April and continue for several months. Once the data is processed, the U.S. Geological Survey will release it publicly through their science base. EGLE officials stated they will continue to use the data to make interpretations and inform resource management decisions.

Broader Implications

Having a better understanding of groundwater resources can lead to improved resource management and protection of Michigan's water supplies. Much of Michigan's drinking water comes from groundwater systems, which EGLE describes as "comparable to a sixth Great Lake: huge, but not limitless."

The survey represents a significant investment in understanding Michigan's critical water resources and ensuring sustainable management for future generations. The data will help inform decisions about water withdrawals, conservation efforts, and protection of groundwater-dependent ecosystems throughout the state.

Residents who see low-flying helicopters with large sensor equipment overhead in Southwest Michigan during the coming months will be witnessing the cutting-edge technology used to protect Michigan's groundwater for years to come.