Date of Award
Master of Science - Environmental Sciences
Dr. Kenneth Farrish
Dr. David Creech
Dr. I-Kuai Hung
Dr. Frantisek Majs
Galveston Island, Texas, is frequently affected by hurricanes. In 2008, Hurricane Ike inundated much of the island with seawater, causing elevated soil salinity levels that killed much of the vegetation on the island, including tens of thousands of trees. Residual salinity in soils and groundwater has hampered vegetation re-establishment in some areas.
This project aims to create a map product that displays the current soil salinity and sodicity levels on Galveston and Pelican Islands. The existing USDA Natural Resource Conservation Service (NRCS) Galveston County Soil Survey map units were used as a base for the project. ArcGIS Desktop software was used to establish a sampling design with randomly located sampling points within each soil survey map unit. Samples were taken at 200 different soil sampling plots across Pelican and Galveston Island. A total of 328 samples were collected, composed of 129 subsurface and 199 surface samples. The soil samples were tested in the laboratory for pH, macro-and micronutrients, and saturated paste properties such as sodium adsorption ratio (SAR) and electrical conductivity (EC). The data was entered into ArcGIS for analyses, and an interpolated surface using inverse distance weighted (IDW) was created.
The average salinity for the soil samples in this study varied from the predicted values produced by the NRCS Web Soil Survey. Surface samples had a higher average EC but a lower average SAR than subsurface samples. There was a significant difference between surface and subsurface EC levels, while there was no significant difference in SAR values. There is a positive correlation between EC and SAR levels. About half the samples are not salt impaired. The other half were classified as saline, sodic, or saline sodic. The areas with higher salinity and sodicity included the dredge material on Pelican Island, the tidal flats on the Galveston Bay coast, and the industrial areas close to the coastline. The large suburban and downtown area of Galveston Island had the lowest salinity and sodicity.
Murray, Rachel, "SOIL SALINITY AND SODICITY OF GALVESTON AND PELICAN ISLANDS, TEXAS" (2022). Electronic Theses and Dissertations. 466.
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