Creating Piper Diagrams

( The Hydrochemistry / Piper Diagram Program )

This RockWorks Geological Utilities tool is used to read a listing of ion concentrations from the datasheet and create a Piper diagram for groundwater ion concentration analysis.

Below is a summary of all of the parts of a Piper diagram.

Piper diagrams consist of three parts: Two trilinear diagrams along the bottom and one diamond-shaped diagram in the middle.

The trilinear diagrams illustrate the relative concentrations of cations (left diagram) and anions (right diagram) in each sample. For the purposes of a Piper diagram, the cations are grouped into three major divisions: Sodium (Na+) plus Potassium (K+), Calcium (Ca++), and Magnesium (Mg++). The Anions are similarly grouped into three major categories: Bicarbonate (HCO3-) plus Carbonate (CO3--), Sulfate (SO4--), and Chloride (Cl-). Each sample will be represented by a point in each trilinear diagram; unique symbols may be selected for each sample and can be referenced in a symbol index at the top of the diagram. Symbols may be accompanied by labels if desired.

Concentrations entered in the source data file in units of milligrams per liter are converted to milli-equivalents per liter for display on the diagram. (See Conversion Factors.)

The diamond field is designed to show both anion and cation groups. For each sample, a line is projected from its point in the cation and anion trilinear diagrams into the upper region; where the lines intersect, the symbol is plotted. Circles may be plotted around each point to illustrate total dissolved solids ("TDS") for the sample. The total dissolved solid computation will include all components listed in the data file ("standard" ions and additional ions).

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