USGS Groundwater Information: Branch of Geophysics
Handheld Thermal Imaging Cameras > Example: Fish-Population Dynamics Study
USGS Leetown Science Center recently used a handheld thermal imaging camera in a stream-flow and temperature study to inform the development of local fish-population dynamics models. The thermal imaging camera was used to visualize groundwater discharging into a stream as well as the mixing of tributary stream waters flowing into a main trout stream.
Sample videos and photo (fig. 1) taken during the Leetown Science Center study and show examples of output from the camera. In these images, water temperature is indicated by color: warmer water is represented in yellow and cooler water in purple.
Figure 1. Thermal image indicates water temperature, where warmer temperatures are represented as yellow and cooler temperatures as purple. The image presents a groundwater seep at the edge of a stream, where groundwater discharge (yellow) is flowing over rocky/sand substrate and mixing with the colder (purple) stream. Temperature is in degrees Celsius. Image is of an area about one-half meter wide. Image courtesy USGS Leetown Science Center.
In the video below, the thermal image is displayed as an inset of the real-color video taken in the field where a tributary flows into the main channel of a stream. In the thermal image, relatively cooler water (purple) on the left from the tributary mixes with the warmer stream water (orange) on the right. By displaying the thermal image as an inset of the larger real-color image, the user can easily identify where certain heat signatures correspond to visible objects; in other areas, such as where waters of different temperatures mix, the camera visualizes water temperature differences that are not otherwise visible to the naked eye.
[Or view the video on YouTube : http://www.youtube.com/watch?v=Z3uvONj582w&feature=relmfu ](Video courtesy USGS Leetown Science Center.)
The second video demonstrates how the camera can be used to identify thermal anomalies interpreted to represent groundwater/surface-water interactions in the field. In this video, warmer groundwater (yellow) is discharging from a stream bank at the top of the image and mixing into cooler stream water toward the bottom of the image (purple).
[Or view the video on YouTube : http://www.youtube.com/watch?feature=player_embedded&v=e60P2vFQauU ](Video courtesy USGS Leetown Science Center.)
For more information, refer to the USGS Leetown stream-flow and temperature study.
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