A stiff plot is a visualization that displays the ionic composition of water samples. It visualizes cations and anions—typically the four major ones on each side of a central axis—as polygonal shapes, offering a “chemical fingerprint” of the sample.

To create one, you need to plot concentrations of cations on the left and anions on the right. Each ion’s concentration will be represented by its horizontal distance from a central vertical zero-axis, and connecting these points will form a closed polygon. The shape of that polygon will ultimately reflect the water’s chemistry.

Once you’ve created a stiff plot, it will show how one sample compares to another by illustrating the shape and size of the different diagrams. No lengthy data tables or guesswork are required to get key insights across to stakeholders. With a stiff plot, you just have a great data visualization that you can easily explain to viewers who want to understand the ionic compositions of water samples.

When it comes to visualizing water chemistry, few plots offer the same clarity and efficiency as a stiff plot. That’s why scientists across disciplines rely on them. But to put the benefits of this visualization into perspective, here are five key advantages of creating a stiff plot.

Stiff plots let you compare the ionic makeup of different water samples at a glance. Similar shapes mean similar chemistry. Distinct shapes suggest variation and possibly contamination or changes in the water source.

Why it matters: Instead of scrolling through rows of cation and anion data, you can spot similarities or differences visually. This is essential when comparing samples from multiple wells, aquifers, or time periods.

Whether you’re tracking groundwater chemistry over time at a single location or comparing samples from various sites on a map, stiff plots let you spot trends fast.

Why it matters: When you plot stiff diagrams across space or time, patterns become obvious, like seasonal shifts or growing contamination plumes.

Each stiff diagram packs the relative concentrations of up to eight major ions into one tidy shape. That means you don’t need to provide lengthy chemical breakdowns every time you present results.

Why it matters: A stiff plot communicates complex chemical data clearly and concisely, making it perfect for reports, regulatory documents, or on-field decision-making.

Different water sources have different chemical signatures. When two sources mix—like fresh groundwater blending with seawater—it will show up in the stiff plot as a shape that reflects both sources.

Why it matters: Spotting these mixing zones is critical in environmental investigations, especially when evaluating the health of drinking water supplies or assessing aquifer sustainability.

Because the plots are visual, compact, and quick to interpret, they’re especially useful in the field. You can include stiff plots in well logs or overlay them on maps for instant insight.

Why it matters: Instead of waiting to crunch the numbers back at the office, you can assess site conditions in real time, saving time and improving responsiveness.

Given their benefits, it’s no wonder stiff plots aren’t one-and-done visuals. You often need to recreate them with fresh data. In fact, here are just a few situations when you might find yourself doing that very thing (if you haven’t already).

You’re a hydrogeologist monitoring wells near a coastline where over-pumping threatens to draw seawater into freshwater aquifers. Initial stiff plots show a normal ionic balance. But after a few months of heavy pumping, new data suggest rising sodium and chloride levels. By recreating the original stiff plot with updated data, you can confirm the intrusion and document the shift clearly.

You’re an environmental consultant assessing whether a factory is impacting river chemistry. Samples are taken upstream, beside the facility, and downstream. You plot each sample using stiff diagrams to compare chemical signatures. Later, additional samples are collected, requiring you to recreate the same plots with new data for a clear before-and-after comparison.

You’re a remediation engineer collecting water samples from several monitoring wells before starting a cleanup project. The results are plotted using stiff diagrams. Months later, after treatment is complete, another round of samples is collected. You recreate the stiff plots to evaluate the change in water chemistry, helping determine whether the remediation reduced contaminants and altered the chemical balance as expected.

Whether you’re making a stiff plot for the first time or recreating one with fresh data, there’s no reason it needs to be a hassle. The easiest way to create and recreate this visualization is to use the Stiff Frame Template or Stacked Stiff Plots for Water Sample Analysis Template in the Golden Gallery, a curated library of templates that you can enjoy in Grapher Beta. 

This library offers dozens of publication-ready visuals that are clean, customizable, and easy to use. Each template also gives you a pre-configured layout, so you don’t have to do anything but plug in your data and make any final adjustments. 

To get started, use the Stiff Frame Template to visualize the major ion composition, concentrations, or contaminant levels in water samples. On the other hand, if you want to not only display the major ion chemistry of groundwater samples but also have a shape that acts like a “fingerprint” of that water sample’s chemical signature to compare multiple wells, depths, or time intervals, use the Stacked Stiff Plots for Water Analysis Template.

Explore the Stiff Frame Template →

Stacked Stiff Plots for Water Analysis Template →

Discover whether you have access to Grapher Beta  →