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Remote Sensing Techniques to Quantify Dye Dispersal

By Columbia Environmental Research Center

By Brandon Sansom, PhD and Robert Jacobson, PhD

May 19, 2021

The Searcy’s Bend dye experiment was designed to collect data on dye transport and retention at multiple, complementary scales. In addition to data collected on fluorometers at specific points, the experiment included multiple aircraft and multiple sensing techniques to evaluate how dye was transported over scales of centimeters to thousands of meters.

Missouri University of Science and Technology graduate student Paul Manley prepares an unmanned aerial system (UAS) for flight.
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Missouri University of Science and Technology graduate student Paul Manley prepares an unmanned aerial system (UAS) for flight. This UAS was equipped with a hyperspectral camera and collected imagery of the dye moving through the Searcy Bend Interception-Rearing Complex.

Unmanned aerial systems (UAS’s) were flown by scientists from USGS and Missouri University of Science and Technology. Two UAS’s flew at 1200 ft above ground level (AGL) and collected standard color video (4 visible bands) of the dye movement through the Searcy Bend Interception-Rearing Complex, which was designed by the Corps of Engineers to intercept pallid sturgeon larvae to allow them to grow and survive in the Missouri River. A third UAS flew at 400 ft AGL and collected hyperspectral imagery. The hyperspectral imagery consists of several hundred spectral bands that provide much more information about transported constituents in the water compared to the visible bands.

USGS scientist Matthew Burgess operates an unmanned aerial system (UAS) during the dye trace experiment.
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USGS scientist Matthew Burgess operates an unmanned aerial system (UAS) during the dye trace experiment. This UAS collected standard 4-band color imagery of the dye moving through the Searcy Bend Interception-Rearing Complex.

Simultaneously, a fixed-wing aircraft flew at 5600 ft AGL and collected multi-spectral (three visible bands plus infrared) data by flying 20-minute continuous loops 8 times over the 7-mile study reach. The imagery from the fixed-wing aircraft is lower resolution compared to the UAS data but provides the comprehensive spatial view that includes all the complexity of this reach, including the main channel, slow areas behind wing dikes, shallow areas along sand bars, and secondary channels.

A composite image created from the 4-band multi-spectral image captured from the fixed-wing aircraft of the entire 7-mile study
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A composite image created from the 4-band multi-spectral image captured from the fixed-wing aircraft of the entire 7-mile study reach. The four insets (A-D) are of the area highlighted by the red outline and depict four subsequent 20-minute loops of the dye plume moving through the Searcy Bend Interception-Rearing Complex.