WATER COLOR OF MINNESOTA’S SENTINEL LAKES (SLICE) BY SATELLITE REMOTE SENSING

Surface waters are preciously vital resources requiring costly time and labor to monitor for effective water quality management. New applications of water color analysis by satellite remote sensing are a promising approach to water quality monitoring for scientific, industrial, recreational, and cultural benefit. This research expands previous applications of lake water color analysis and pioneers water color patterns using chromaticity diagrams for midcontinent lakes in Minnesota, USA. The results of this project will be the first accounts of lake water color, variability of water color by ecoregion, and annual water color temporal consistency within major ecoregions of Minnesota. NASA’s Landsat 8 OLI satellite provides an active historical record of visible light reflectance of the Earth’s surface since 2013. Chromaticity analysis quantifies unbiased interpretation of dominant visible wavelength as water color from tristimulus reflectance samples. The Sustaining Lakes In a Changing Environment (SLICE) program, ordains “Sentinel Lakes” representative of lake populations within major ecoregions of Minnesota. Visible light reflectance will be extracted annually from the deepest area within Sentinel Lakes in late summer, when peak insolation bolsters trophic activity, and plotted to chromaticity diagrams. To aid future investigation of water color variability by ecoregions, cartographic representation of Sentinel Lake modal water color will be created. Graphical displays of modal dominant visible wavelength will yield a quantifiable water color for comparing ecoregions to one another. Ecoregions are anticipated to possess distinguishable water colors. However, Sentinel Lakes within the same ecoregion are expected to share consistent water color. Additionally, individual Sentinel Lakes are hypothesized to change color incrementally with time, evaluated with annual chromaticity plot and graphic trend comparisons. Cost reduction, historical backlogs, and improving temporal and spectral resolutions are some of the major benefits for further developing satellite remote sensing water color methodology for water quality monitoring.