Significance and Use
Each year, many thousands of water samples are collected, and the chemical components are determined from natural and human-influenced groundwater sources.
An understanding of the relationship between the similarities and differences of these water analyses is simplified by use of data analytical methods and the display of the results of these methods as pictorial diagrams.
This guide presents a compilation of the diagrams used for illustrating the results of these methods.
This type of diagram summarizes data from a number of analyses to allow for an objective comparison between the chemical and related parameters.
The diagrams based on data analytical calculations described in this guide display the following; time and areal trends; maximums, minimums, and means; relationships between chemical and associated parameters; significant outliers; distributions; and a summary of a number of data parameters.
The objective interpretations of the origin, composition, and interrelationships of groundwater are common uses of the diagrams based on data analytical calculations.
The origin of the water may be postulated by the amount and the relationship of the chemical constituents in a sample of water analyses summarized on the diagrams.
The chemical composition of the water can be scrutinized for distinct characteristics and anomalies by use of the diagrams.
A graphical comparison of distinct data sets of chemical analyses allows the investigator to evaluate the interrelationships of the groundwater from separate locations.
This is not a guide for the selection of a diagram for a distinct purpose. That choice is program or project specific.
Note 5—For many hydrochemical research problems involving the scientific interpretation of groundwater, the ′analytical water-analysis diagram' is only one segment of several methods needed to interpret the data.
Scope
1.1 This guide covers methods that graphically display chemical analyses of multiple groundwater samples, discrete values and also those reduced to comprehensive summaries or parameters. Details required by the investigator to fully use the methods are found in the listed references. The methods included in this guide are many of the graphical procedures that were not discussed in two previous guides, Guides D5738 and D5754.
Note 1—The graphic methods in this guide apply to both raw and transformed data, for example, unaltered medians, maximums, and minimums and transformed means, square-roots, frequency distributions, and so forth. The methods are often computational intensive, requiring the use of a digital computer. Some graphical methods illustrate the results of the statistical analysis of a sample data set. For example, box plots are graphical portrayals of the maximum, minimum, median, 25th percentile, and 75th percentile of one variable, such as the chloride ion from a group of chemical analyses.
Besides chemical components, other variables that may be plotted to show an interdependence with water chemistry include time, distance, and temperature.
1.2 This guide on diagrams based on data analytical calculations is the third of several documents to inform the hydrologists and geochemists about traditional graphical methods for displaying groundwater chemical data.
Note 2—The initial guide described the category of water-analysis diagrams that use two-dimensional trilinear graphs to display, on a single diagram, the common chemical components from two or more analyses of natural groundwater.
1.2.1 The second guide described the category of water-analysis diagrams that use pattern and pictorial methods as a basis for displaying each of the individual chemical components determined from the analysis of a single sample of natural groundwater.
1.3 This guide presents a compilation of diagrams that allows for transformation of numerical data into visual, usable forms. It is not a guide to selection or use. That choice is program or project specific.
1.4 Many graphic techniques have been developed by investigators to illustrate the results of the data analytical computations to assist in summarizing and interpreting related data sets. In this guide, selected graphical methods are illustrated using groundwater chemistry data.
1.5 The basic or original format of each of the graphical techniques given in this guide has been modified in several ways, largely depending upon the data analytical techniques used by the investigators. Several minor modifications are mentioned, some significant revisions are discussed in more detail.
1.6 Notations have been incorporated within many diagrams illustrated in this guide to assist the reader in understanding how the diagrams are constructed. These notations would not be required on a diagram designed for inclusion in a project document.
Note 3—Use of trade names in this guide is for identification purposes only and does not constitute endorsement by ASTM.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.8 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.
