A Durov diagram is a composite plot consisting of 2 ternary diagrams used by hydrogeologists to visualize and compare the chemical composition of multiple water samples.

Durov diagram comparing multiple monitoring well water samples created in Grapher

How to read a Durov Diagram:

A Durov diagram displays the relative concentration of the 6 major ion groups in a group of samples with two ternary plots. The ternary diagram on the left represents the cations. The ternary diagram on the top represents the anions. The sum of ions in each of these two groups is forced to be 100% for each sample element.

The square plot in between the two ternary diagrams is a projection of the cation and anion ternary diagrams. Samples that are grouped closely in the Durov projection square are assumed to have similar compositions of anions and cations. 

In the plot above MW-8 and MW-11 would be an example of 2 similar samples that have a higher concentration of cations than the rest of the samples.

Extended Durov Diagram:

One can also use an Extended Durov diagram which contains a PH plot at the bottom and a TDS (Total Dissolved Solids) plot to the right. By including the plots in an Extended Durov diagram hydrogeologists can make further geochemical comparisons.

The Extended Durov diagram below shows that MW-8 and MW-11 both have a similarly high amount of Total Dissolved Solids on the right rectangle. But, MW-8 has a higher PH in the bottom plot.

Why is a Durov Diagram Used?

By clustering water samples of similar chemical composition hydrogeologists can reveal relationships and properties for entire sample groups. Grouped samples can then be sorted into hydrochemical facies.  Facies provide insight into the geochemical processes occurring within an aquifer, such as origin, mineral dissolution, ion exchange, and mixing between different types of groundwater. 

Knowledge of these processes help hydrogeologists to track changes in the groundwater chemistry over time. Identifying potential sources of contamination and evaluating the effectiveness of remediation efforts. Ultimately, guiding stakeholder decisions related to water resource management, land use planning, and environmental protection.

To learn how to create your own Durov Diagram click here: Create a Durov Plot in Grapher