Piper diagram


In 1944, Arthur M. Piper proposed an effective graphic procedure for presenting water chemistry data to help in understanding the sources of the dissolved constituents in water. This procedure is based on the premise that cations and anions in water are generally in chemical equilibrium.
, Zimbabwe. Data source:
A piper diagram is a graphical representation of the chemistry of a water sample or samples.
The cations and anions are shown by separate ternary plots. The apexes of the cation plot are calcium, magnesium and sodium plus potassium cations. The apexes of the anion plot are sulfate, chloride and carbonate plus hydrogen carbonate anions. The two ternary plots are then projected onto a diamond. The diamond is a matrix transformation of a graph of the anions and cations.
The required matrix transformation of the anion/cation graph is:
The piper diagram is suitable for comparing the ionic composition of a set of water samples, but does not lend itself to spatial comparisons. For geographical applications, the Stiff diagram and Maucha diagram are more applicable, because they can be used as markers on a map. Colour coding of the background of the Piper diagram allows linking Piper Diagrams and maps
Water samples shown on the Piper diagram can be grouped in hydrochemical facies. The cation and anion triangles can be separated in regions based on the dominant cation or anion and their combination creates regions in the diamond shaped part of the diagram.