Date of Award

Spring 5-11-2022

Document Type

Thesis

First Advisor

Caroline Solomon

Second Advisor

Susan Natali

Abstract

The Yukon Kuskokwim Delta region of Alaska consists of over 100,000 small lakes; it is one of the largest lake-dense regions of Alaska. These small lakes are critical aquatic ecosystems that provide habitats for wildlife and play an important role in carbon and nutrient cycling. Lakes in the Yukon Kuskokwim Delta have a wide range of visible and near-infrared satellite spectra, which can vary over small spatial scales. These spectral differences may provide insight into the environmental properties of these small shallow lakes. Therefore, we want to investigate the relationship between the spectral data and environmental differences in these lakes. To better understand variability in properties of lakes across the Yukon Kuskokwim Delta region, we sampled 32 lakes across three sample regions (each region〜70km apart) described as the Plateau, Southern, and Western regions. At each lake, we measured temperature, dissolved oxygen, specific conductivity, and pH, and collected surface water for analysis of chlorophyll, dissolved organic matter (DOM), chromophoric dissolved organic matter (CDOM), total dissolved nitrogen, and inorganic nutrients such as nitrate, ammonium, and phosphate. This study was supported by lake depth and surficial deposit mapping data from literature. Based on the four Sentinel bands used in this study, lake color can be correlated to different environmental lake properties as well as environmental regions. Lakes of the same coloration generally cluster together based on environmental properties; however multiple different colors may cluster together based on region. We also found that individual bands can be correlated to various environmental factors. For our lakes, the red and NVIR spectral wavelengths may be a good indicator for CDOM concentrations. Understanding associations between satellite imagery of shallow lakes in the Yukon-Kuskokwim Delta can further inform the region's lake ecology, geomorphology, and hydrology, which is critical due to rapid landscape changes that are occurring across this region that impacts our understanding of the consequences of human-induced climate change. This kind of remote sensing could transform the capacity to understand current and historical satellite imagery, future monitoring of lakes, and potential changes in the YK Delta by taking environmental parameters into account.

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