ANALYSES OF SALINITY INTRUSION MECHANISMS IN THE SOUTH TEXAS COASTAL AQUIFERS USING MULTIPLE STATISTICAL TECHNIQUES

Cenozoic sediments that underlie the coastal plain of Texas are tens of thousands of feet thick at the coastline. Subsidence of the deposition basin and rising of the land surface caused the stratigraphic units to thicken gulfward. Growth faults greatly increased the thickness of some stratigraphic units within short distances. Water chemistry data collected for a few selected years between 1950 and 2010 will be analyzed to determine the depth variation and spatial differences of groundwater chemistry in the Evangeline and Chicot aquifers located along the South Texas coastal area. Several statistical procedures such as Tukey lines, correlation analysis, simple linear regression and Principal Component Analysis (PCA) will be applied using the statistical software R and SAS. Assuming that the Total Dissolved Solids (TDS) concentration is a good indicator of salinity distribution, a multiple regression model will be run to determine the relative influences of major ions on the observed TDS values. A graphical and quantitative comparison between the observed TDS and the model predicted TDS values will be conducted to determine the spatial variation of the relative proportion of major ion concentration in groundwater. Major ion hydrogeochemistry evolution analyses will be conducted by comparing observed and model predicted TDS values. Finally, understanding the approximate location of salinity affected area will be helpful to interpret the basic mechanisms of salinity intrusion in the study area.