Aerial Research for Geology and Groundwater in Southwest Michigan

Information provided by Lon Nordeen, MLSA Secretary

​A major scientific investigation is currently underway in southwest Michigan focused on improving understanding of groundwater resources and subsurface geology using advanced airborne geophysical technology. The study is a collaborative effort between the U.S. Geological Survey and the Michigan Department of Environment, Great Lakes, and Energy, in partnership with the airborne survey company SkyTEM.
This initiative is part of the broader Hydrologic Enhancement for Michigan (HEMI) project, which is designed to improve statewide understanding of both groundwater and surface water systems.

Purpose of the study

Michigan’s water resources are extensive and heavily relied upon for drinking water, agriculture, industry, and ecosystem health. More than 40% of residents depend on groundwater as their primary water source.
However, groundwater systems are complex and not fully mapped at high resolution in many areas. This study was developed to address those gaps by combining traditional monitoring networks with modern airborne imaging technology.
The primary objectives include:

• Improving understanding of subsurface geology and aquifer systems
• Identifying how groundwater moves through underground formations
• Evaluating connections between groundwater and surface water
• Supporting long-term water resource planning and management
• Providing scientific data for sustainable water use decisions

Airborne electromagnetic surveying

At the core of the project is an airborne electromagnetic (AEM) survey system mounted on a helicopter. The system is operated by SkyTEM and is designed to measure variations in the Earth’s subsurface electrical properties.
The helicopter typically flies at low altitude—about 200 feet above ground—while towing a large hoop-shaped sensor system beneath it. This system transmits rapid electromagnetic pulses into the ground and records how those signals respond as they pass through different materials.
Different subsurface materials respond in distinct ways:

• Sand and gravel tend to resist electrical current
• Clay and water conduct electrical signals more easily
• Bedrock formations produce unique signatures

By analyzing these responses, scientists can generate detailed three-dimensional models of what lies beneath the surface—sometimes extending to depths of more than 1,000 feet.

What the data provides

Once processed, the collected data is used to build high-resolution 3D maps of underground conditions. These models can identify:

• Depth to bedrock
• Aquifer locations and thickness
• Distribution of sand, gravel, and clay
• Potential groundwater flow pathways
• Areas of high or low groundwater availability

This level of detail helps fill critical data gaps in regions where drilling and well data alone are not sufficient.

Broader HEMI monitoring effort

The airborne survey is one component of the larger HEMI initiative, which also includes enhancements to Michigan’s water monitoring systems.
Surface water monitoring improvements

• Evaluation and expansion of streamflow gaging stations across rivers and streams
• Enhanced monitoring during low-water conditions when impacts are most significant
• Upgrades to stream gages, including temperature sensors where needed

Groundwater monitoring improvements

• Review of existing groundwater monitoring well networks
• Installation of additional wells in data-limited areas
• Long-term tracking of groundwater levels and trends statewide

Together, these efforts create a more complete picture of how water moves through Michigan’s interconnected hydrologic systems.

Why this work matters

The data generated through this study will help answer key questions, including:

• How are groundwater resources changing over time?
• Where are additional monitoring sites needed?
• How does groundwater pumping affect rivers, lakes, and wetlands?
• Where are the most sustainable aquifers located?
• How can future water use be managed responsibly?

These insights are especially important in southwest Michigan, where population growth, agricultural irrigation demands, and known groundwater stress areas require careful resource planning.

Expanding use of airborne geophysics

Airborne electromagnetic surveying is not unique to Michigan. Similar studies have been conducted across multiple states, including California, Colorado, Florida, Mississippi, and Wisconsin, as well as internationally. These projects have proven valuable in improving groundwater mapping, environmental assessment, and resource management.

Acknowledgment

This article is based on information provided by Lon Nordeen, MLSA Secretary, summarizing the ongoing Hydrologic Enhancement for Michigan (HEMI) airborne geophysical and groundwater research program led by USGS and EGLE.