Monitoring Harmful Algal Blooms in Small Inland Lakes Utilizing Sentinel-2 Multispectral Imagery

Abstract

Population growth and climate change continue to jeopardize food security. Modern agricultural practices adapt to these changes by increasing the use of chemicals and fertilizers which directly affects our water quality. Harmful Algal Blooms (HABs) is an overgrowth of blue-green algae, in some cases it contains toxic bacteria caused by excess nutrients in water sources. Local governments test water sources to ensure levels of algae remain safe for consumption and water activities, however the cost to test the water remains high. There is remotely sensed imagery currently that can identify and monitor HABs, however the spatial resolution is too low for small inland lakes and rivers to provide accurate data. This project uses Sentinel-2 multispectral imagery to identify HABs using a normalized difference chlorophyll index (NDCI). The results of the project revealed that the application successfully displayed the location and extent of possible algal blooms based on NDCI values and visual interpretations. The in-situ samples of excess chlorophyll did correlate with the increased chlorophyll of the index when there was in-situ sample data available. As a recommendation for use of NDCI, local testing facilities could focus their sample locations to the locations of where there is high chlorophyll content.