For the first time, we are using the latest airborne electromagnetic survey technology— helicopter time-domain electromagnetic— to map the geology of Champaign County, which is a big step forward for our community to better understand our water resources. On November 15, 2022, the Illinois State Geological Survey (ISGS) will begin a helicopter-based geophysical survey of the Mahomet aquifer in Champaign County, Illinois.

A New Map of the Mahomet Aquifer

This survey will help scientists map the extent and characteristics of the Mahomet aquifer sand deposits within Champaign County. This effort will produce the most comprehensive measurements and maps of the Mahomet aquifer in the county to date. Data from this project will help build the most detailed three-dimensional map of the Mahomet aquifer and help address important questions regarding Champaign County’s water supply, water quality, water-supply, recharge, security and sustainability.

Flight Details

The survey will be conducted by a helicopter flying at an altitude of 100-250 feet (30-75 m) and a speed of 20 miles per hour (about 32 km/h). The helicopter will traverse across nearly the entire county, but it will not fly over buildings, developed areas or highly populated areas. The geophysical equipment will be suspended under the helicopter at about 115 ft (35 m) above the ground. The noise from the helicopter at any given location on the ground has been described as the equivalent to a truck traveling past on a highway and lasts for about two to four minutes. The helicopter will fly back and forth across the county in gridlines (flight lines). It will then return about 2,100 ft (650 m) from its initial spot approximately 30 minutes later.

Safety

These geophysical surveys present no risks to humans, animals, or infrastructure. A magnetic field is generated by the process, but the magnetic field exposure is 100 times less than someone riding on an electric train. It’s comparable to standing in front of your house, and it is actually safer than watching an LCD or plasma TV or even blow-drying your hair!

Additional Resource

The Future of Science of the Mahomet Aquifer, 2018 [ISGS Circular 594]. Authors: Steven E. Brown, Jason F. Thomason,and Kisa E. Mwakanyamale. Download free: https://hdl.handle.net/2142/99079

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