Date of Award

2018

Document Type

Open Access Thesis

Department

Geography

Sub-Department

College of Arts and Sciences

First Advisor

Kirstin Dow

Abstract

This study presents the first comparison of Landsat 8 OLI and Sentinel-2A MSI imagery in identifying soil salinity using soil physiochemical, spectral, statistical, and image analysis techniques. By the end of the century, intermediate sea level rise scenarios project approximately 1.3 meters (4.2 feet) of sea level rise along the coast of the southeastern United States. One of the most vulnerable areas is Hyde County, North Carolina, where 440 square miles of agricultural lands are being salinized, endangering 4,200 people and 40 million dollars of property. To determine the best multispectral sensor to map the extent of salinization, this study compared Landsat 8 OLI and Sentinel-2’s identification of electrical conductivity (EC). The EC of field samples were correlated with handheld spectrometer spectra resampled into multispectral sensor bands. Using an iterative ordinary least squares regression, it was found that EC was sensitive to Landsat 8 OLI bands 2 and 4 and Sentinel-2A bands 2 and 6. Respectively, the R2 and RSME of 0.04-0.54 and 0.90-1.90 for the OLI, and 0.04-0.69 and 0.73-2.83 for Sentinel-2, suggests that the increased spatial resolution of Sentinel-2 provides a more precise measurement of salinity location. Image analysis using band math estimates that salt crusts make up approximately 1.4% (Sentinel-2) to 2.57% (OLI) of bare soil indicating that surrounding land is saline though not currently identifiable through multispectral analysis. As sea levels rise, accurately monitoring soil salinization will be critical to protecting coastal agricultural lands. Sentinel-2’s superior spatial and temporal resolution make it a superior sensor for salinity tracking.

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