Author

Sae Young Lee

Date of Award

5-2024

Document Type

Independent Study

Degree Name

Master of Science (MS)

Department

Geography & Geographic Information Science

First Advisor

Dr. Gregory Vandeberg

Abstract

The water quality of recreational lakes degrades with Harmful Algal Blooms (HABs). HABs can block sunlight, lower oxygen levels, and may produce toxins. Industrial and domestic waste and fertilizer runoffs can enrich nutrients for HABs. Chlorophyll-a (Chl-a) is a significant indicator for tracking HABs and has been monitored increasingly using remote sensing techniques. In search for significant trends in hotspots of Chl-a concentrations in small and medium lakes of northeastern North Dakota, Chl-a water samples were collected in summer and fall of 2023. The study lakes include: Fordville Dam Recreation Area, Larimore Dam RecreationArea, Homme Dam Recreation Area, and South and North Golden Lakes. Six multi-bandcombination indexes of Sentinel-2 and Landsat 8 remote sensing satellite imagery were compared with in-situ water sampling for Chl-a concentration. The Chl-a concentration trends and patterns were discovered through Hotspot Analysis using the Getis-Ord Gi* method.

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