Combining chemometric and graphical methods as tools in hydrogeologic characterization

A chemometric method (principal component analysis) was used in combination with two graphical methods (mapping a ratio of major cation concentrations [as percent milliequivalents per liter (meq/L)] and plotting Piper trilinear diagrams [Piper, 1944]) to assess groundwater movement in a key region of a site affected by volatile organic compounds (VOC) and perchlorate. All three methods of interpretation showed a likely relationship between groundwater discharging from a spring and from two other sampling points, and suggested that mixing of water of at least two hydrochemical types was occurring in the area. These results were used to develop the conceptual model for groundwater flow at the site and to assist planning for subsequent additional characterization and groundwater management activities.