Piper diagram

A Piper diagram is a graphic procedure proposed by Arthur M. Piper in 1944 for presenting water chemistry data to help in understanding the sources of the dissolved constituent salts in water.

This procedure is based on the premise that cations and anions in water are in such amounts to assure the electroneutrality of the dissolved salts, in other words the algebraic sum of the electric charges of cations and anions is zero.

The cations and anions are shown by separate ternary plots.

[4] The Piper diagram is suitable for comparing the ionic composition of a set of water samples, but does not lend itself to spatial comparisons.

[7] The cation and anion triangles can be separated in regions based on the dominant cation(s) or anion(s) and their combination creates regions in the diamond shaped part of the diagram.

A piper diagram and two ternary diagrams on the composition of intrusive volcanic rocks; see QAPF diagram
Piper diagram of water samples from the Mtshabezi River , Zimbabwe . Data source: [ 2 ]
The Piper diagram can be separated in hydrochemical facies. Legend: A: Calcium type; B: No dominant type; C: Magnesium type; D: Sodium and potassium type; E: Bicarbonate type; F: Sulphate type; G: Chloride type; 1: Alkaline earths exceed alkalies; 2: Alkalies exceed alkaline earths; 3: Weak acids exceed strong acids; 4: Strong acids exceed weak acids; 5: Magnesium bicarbonate type; 6: Calcium chloride type; 7: Sodium chloride type; 8: Sodium bicarbonate type; 9: Mixed type