Airborne Electromagnetic (AEM) Survey 2023 - Illinois River Basin

The low-flying helicopter will collect and record subsurface geophysical measurements as part of the U.S. Geological Survey Next Generation Water Observing System (NGWOS) project to support studies of groundwater in the Illinois River Basin.

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The helicopter will fly along pre-planned flight paths relatively low to the ground, hundreds of feet above the surface. A sensor that resembles a large hula-hoop will be towed beneath the helicopter to measure tiny electromagnetic signals that can be used to map features below Earth’s surface. Most survey flight lines will be separated by a half mile to five miles, so the helicopter system will only be visible from any particular location for a short period of time. 

The survey will be conducted by SkyTEM, a specialty airborne geophysical company, through a USGS contract with Woolpert. The helicopter will be operated by experienced pilots from LiveWire Aviation who are specially trained for the low-level flying required for geophysical surveys. The company works with the FAA to ensure flights are safe and in accordance with U.S. law. 

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Where will it happen?

This map shows the airborne geophysical survey area and planned flight paths across the Illinois River Basin in Illinois and northwest Indiana. Surveys will not be flown directly over highly populated areas. Planned flight lines and survey progress can be found online. Map of where the helicopter will be flying:

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Why is measuring subsurface geology important for water quality?

Degradation of groundwater quality has been a rising concern as well as the influence of groundwater connections to our streams. Having a better understanding of aquifer properties, as well as connectivity to the surface (depth to bedrock), allows practical guidance for the development of approaches to maintain a healthy groundwater system. Using AEM allows scientists to develop a 3D image of the subsurface geology to better predict how water moves through those layers and how groundwater and surface water are connected.

How does this benefit the public?

This survey supports public health efforts to help protect groundwater and promote water quality. The results of the survey will:

• Create a better understanding of aquifer properties
• Address groundwater quality
• Improves understanding of the influence of surface activities (agriculture, mining, development, etc.) on groundwater quality

This project uses the strength of local, State, and Federal resources to help many citizens in the Illinois River Basin.

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• Flights are expected to take 3 to 4 weeks depending on weather and flight conditions 

• The helicopter is flying a grid pre-determined flight track based on study locations, so it will be seen several times in the same area  

• The helicopter will fly relatively low, hundreds of feet above ground 

• The helicopter will not fly within 500​ ft of buildings according to Federal Aviation Administration (FAA) rules, and will make efforts to fly around people or large equipment on the ground 

• The electromagnetic device will not harm plants, animals, or humans 

• The low flying helicopter may startle wildlife and cattle and the helicopter will make efforts to fly around confined animal areas 

• Local enforcement and conservation contacts are informed of the activity 

• Only depth to bedrock and hydrogeologic properties will be identified through this process.  

Additional Information 

General footage of the surveying equipment: ​https://www.youtube.com/watch?v=qSTddN9njuk 

Example of how to view and use the data: https://www.youtube.com/watch?v=6fbCZLgQPl8 

Contacts