Date of Graduation

5-2020

Document Type

Thesis

Degree Name

Bachelor of Science in Civil Engineering

Degree Level

Undergraduate

Department

Civil Engineering

Advisor/Mentor

Coffman, Richard A.

Committee Member/Reader

Barry, Michelle L.

Abstract

Soil moisture content provides information about the strength, permeability, and compressibility of the soil under investigation. In the research described herein, the relationship between moisture content and reflectance values obtained from spectroscopy was developed to investigate whether in-situ moisture content can be determined in a faster and more efficient way than the current methods. The soil under investigation was laboratory-compacted kaolinite clay mixed with pyranine dye. These specimens were placed beneath an ultraviolet light and a halogen illuminator where reflectance values were collected over a 24-hour period. Correlations were developed from the following methods: 1) spectral indices, 2) continuum analyses through the 1450nm, 1900nm, and 1940nm wavebands, 3) linear regressions between moisture contents and normalized reflectance (initial spectra divided by final spectra), and 4) analytical models of the time dependent moisture content at 1450nm and 1900nm. The 1450nm waveband was found to have the highest correlation between the reflectance values and the moisture contents with coefficients of determination (R2) values greater than 0.922 in all cases. Other wavebands of interest included 1900nm, 1940nm, and 2200nm; however, these bands consistently had lower correlation values. With further study of the 1450nm waveband, in-situ moisture contents can be accurately predicted in a non-intrusive way in the laboratory and in the field.

Keywords

Water Content; Remote Sensing; Near-Infrared Spectroscopy; Wavelength; Spectral Signature; Reflectance Spectroradiometry

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