Handheld Thermal Imaging Cameras for Groundwater/Surface-Water Interaction Studies

Overview

Figure 1. Example of portable, handheld thermal imaging camera used in USGS groundwater studies.

Although airborne and satellite thermal imaging for water-resources studies is common, the availability of robust handheld thermal imaging tools in support of USGS groundwater studies is relatively new. The cameras allow hydrologists to rapidly image real-time variations in temperature at high resolution in the field at scales from a few centimeters to tens of meters. The information can be used to:

• localize groundwater discharge,
• help characterize local hydrogeologic conditions, and
• optimize sampling and monitoring locations.

The small size of the cameras makes them convenient tools for studies in dense urban settings as well as remote field sites (fig. 1). Potential field applications are being explored within the USGS Water Resources Mission Area and in interdisciplinary work across the USGS.

Heat as a Tracer of Water Movement Near Streams

Temperature has long been recognized as an important water-quality parameter. Differences between temperatures in a stream and surrounding sediments can be analyzed to trace the movement of groundwater to and from streams, and to better understand the magnitudes and mechanisms of stream/groundwater (hyporheic zone) exchanges. Figures 2 and 3 show how thermal imaging can be used to rapidly identify, visualize, and quantify differences in water temperature that may indicate groundwater discharging to the surface. To learn more about use of heat as a tracer, see "Heat as a tool for studying studying the movement of ground water near streams."

Figure 2. Thermal image displayed as an inset of the true-color photograph taken in the field. Thermal image indicates water temperature, where warmer temperatures are represented as red and cooler temperatures as blue. The image presents an area where cooler groundwater (blue) may be discharging along a warm stream bank in mid-summer. The photo spans an area about 3 meters across. The temperature scale is in degrees Celsius. (Credit: USGS/Martin Briggs. Public domain.)

Figure 3. Thermal image indicates water temperature, where warmer temperatures are represented as red and cooler temperatures as blue. The image presents an area where warmer groundwater (red) may be discharging into a cooler (blue) stream in late fall at Tidmarsh Farms, Massachusetts. The image spans an area about 6 meters across. Temperature is in degrees Celsius.  (Credit: USGS/Martin Briggs. Public domain.)

Thermal Imaging Camera Use Examples

The USGS Water Resources Mission Area has sponsored handheld thermal imaging camera technology demonstration and evaluation projects by USGS researchers in around the Nation.

Additional Resources

• Fiber-optic distributed temperature sensing for groundwater/surface-water studies