Processing water-chemistry data, Gulf Coast aquifer systems, south-central United States; with summary of dissolved-solids concentrations and water types

Abstract

Procedures used to process about 95,600 water-chemistry analyses of water samples from the gulf coast aquifer systems are described. The descriptions include the retrieval of data from the original records, the various modifications to the data, the analysis and tabulations of the data, and the plotting and contouring of the data on maps to portray the areal distribution of selected physical properties and chemical constituents in the study area. A statistical summary of dissolved-solids concentrations and the mode of both primary and secondary water types are presented by county in tabular array. Water-chemistry data from the original records for the gulf coast aquifer systems and files of processed data have been stored on computer tape. I ro i EXPLANATION REGIONAL AQUIFER-SYSTEM ANALYSIS (RASA) STUDY AREAS Central Midwest Gulf Coast Southeastern Coastal Plain Floridan aquifer system Edwards-Trinity 500 MILES 500 KILOMETERS Figure 1. Gulf Coast Regional Aquifer-System Analysis study area and adjacent Regional Aquifer-System Analysis study areas. This report can be used as a basic reference for describing dataprocessing procedures (fig. 2) used to obtain water-quality data presented in interpretative reports prepared about the chemistry of water in the gulf coast aquifer systems. PROCESSING WATER-CHEMISTRY DATA Data Storage Water Data Storage and Retrieval System Water-Quality File Chemical-analysis data for 76,184 groundwater samples collected in the gulf coast area were coded and stored in the water-quality file of the WATSTORE System (table 1) of the U.S. Geological Survey in Reston, Virginia. This is the main source of the water-chemistry data for this study. The data were stored in WATSTORE by station identification number. Other identifiers are agency, State, county, site, station name, and geologic unit. Individual analyses are stored by date collected within each station record. Each property and constituent associated with each analysis is identified by a unique five-digit code. In addition to chemical data* the file also contains results of physical, radiochemical and biological analyses of either single or composite water samples (Hutchinson, 1975). However for this study, only the physical properties and chemical constituents were processed and analyzed to provide the information needed for interpretative reports. Brine Computer-Tape File Chemical analyses of 12,388 water samples collected from oil test and production wells in Texas and Louisiana by oil companies is a second source of water-chemistry data in the gulf coast area.