• Erik Sauer

Lower Henry’s Fork Drone Campaign

Since 2019, my mentor Christina Morrisett has been researching the hydrology of the lower Henry’s Fork along with several summer interns, and each has contributed to a different aspect of her PhD research. In 2019, HFF intern Ashly Loibman identified and photographed groundwater seeps along the lower Henry’s using a handheld thermal camera. A seep in this case means that water is flowing from underground through small openings in dirt and gravel and entering the river. Having a better idea of the location, frequency, and temperature of the seeps of course led to more questions about their impact on the river. Primarily, we wanted to see if the temperature effect of the seeps was visible at a greater scale.

Here enter drones, which can photograph acres of river and the surrounding terrain in a single flight. Dr. Sarah Null, a professor at Utah State University and advisor to my mentor Christina Morrisett, has used drones for research in the past and back in June, Christina and Dr. Null flew eight neighboring sections of the Henry’s Fork just south of St. Anthony to gather thermal imagery. As the Geospatial Groundwater and Stream Temperature Intern here at the Henry’s Fork Foundation, one of my primary projects for the summer has been preparing for and leading another series of drone flights on the lower Henry’s Fork, taking place July 2124. Each flight takes somewhere between 15 and 25 minutes and uses a preprogrammed flight path set by Dr. Null. While flying, we keep the drone within view to ensure it stays on course (and make sure hawks aren’t getting too curious). The drone uses GPS coordinates to track its location and land in the proper spot when it has finished its flight. Using a software called Pix4DMapper, I overlap the collected thermal images to create a single map of the several hundred images taken per flight.

Having now completed these flights, we hope to see the relative thermal impact that groundwater has on the lower Henry’s at higher-flow (1000 cfs in June) and lower-flow (350 cfs in July). At lower river levels, seeps should be more visible as they must travel further across the exposed riverbank to reach the water than they did in June. This section of the Henry’s Fork is near several canals used for irrigating crops, and this could be the source of a good deal of the groundwater that is flowing into the river. Capturing thermal information at this scale can help us understand how to meet irrigation demand while providing cooler refuges for cold-water fish like trout are located. Over the next few weeks I will be working on analyzing the data from the most recent flights, and on August 10th I will be giving a presentation on this work. Anyone interested is welcome to join!

Dr. Sarah Null and Amber Roseberry recording the temperature, pressure, humidity and wind before flight 2

Dr. Null and her husband Dr. Curtis Gray readying the thermal camera at flight point 3

The drone is lifting into the air to start flight 6. The drone typically flies at 100-400 feet to capture the thermal imagery. The drone uses GPS to determine its location and follow a consistent flight path.

A thermal infrared image taken in flight 1 showing a darker section of riverbank which may indicate the presence of a groundwater seep


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