Robert Allen Bean
Katherine Walton-Day
M. Alisa Mast
Evan J. Gohring
Rachel G. Gidley
Natalie K. Day
Nicole D. Gibney
Tyler V. King
2025
<p><span>We present methods to reconstruct historical chlorophyll </span><i>a</i><span> and surface water temperatures from satellite-based remote sensing products for Blue Mesa Reservoir, Colorado, to support algal bloom monitoring. A machine learning model was trained to construct chlorophyll </span><i>a</i><span> concentrations from Sentinel-2 satellite imagery and in situ measurements of chlorophyll </span><i>a</i><span> concentrations (out of bag RMSE = 1.9 μg/L, </span><i>R</i><sup>2</sup><span> = 0.63) and reconstruct summertime chlorophyll </span><i>a</i><span> concentrations over the entire reservoir from 2016 through 2023. Concurrently, we developed an approach to retrieve remotely sensed water temperatures from the Landsat collection 2 provisional surface temperature product (MAE = 0.6°C) and reconstructed summertime surface water temperature records from 2000 through 2023. Finally, we demonstrate how the reconstructed chlorophyll </span><i>a</i><span> and temperature records can yield insight on reservoir dynamics. The chlorophyll </span><i>a</i><span> records indicate that algal blooms have a consistent spatial pattern across multiple years, initiating in the eastern end of the reservoir and spreading to the west over time. Water temperatures increased at a linearized rate of 0.3°C per decade from 2000 through 2023 and were inversely proportional to reservoir water surface elevation. Finally, mean summer remotely sensed chlorophyll </span><i>a</i><span> concentration had a moderately positive correlation with mean summer remotely sensed water temperature.</span></p>
application/pdf
10.1111/1752-1688.70038
en
Wiley
Remote sensing of chlorophyll a and temperature to support algal bloom monitoring in Blue Mesa Reservoir, Colorado
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