Unraveling Connections: Sankey Charts Reveal the Inner Tides of Complex Systems

In a world brimming with data and information, visualizing complex systems is a crucial skill. Among the lesser-known yet incredibly powerful tools for conveying the intricacies of systems is the Sankey chart. Similar to a stream chart, which is now predominantly used for flow rate data, the Sankey diagram has the unique ability to depict the flow of energy, materials, or information between different elements of a system. This article delves into the nuances of Sankey chart creation and explores their diverse applications across various domains.

What is a Sankey Chart?

Sankey diagrams were first created by a German mechanical engineer named Franz Sankey in the late 19th century to depict the efficiencies of steam engines. Over time, these charts have evolved, extending their reach to other applications.

At their core, Sankey diagrams are stream charts with arrows flowing to represent the mass flow of materials, heat, or electricity passing from one system element (or “sankey channel”) to another. The width of each flowing arrow typically represents the quantity of the flow—more flow results in a wider arrow. The cumulative sum of all the streams in a diagram equates to the same quantity at the start and end points.

Characteristics of a Sankey Chart:

Key characteristics of Sankey diagrams include:

Energy Efficiency: A Sankey chart can show the efficiency of energy conversion through a process, making it a favorite among process engineers and energy analysts.
Arrows Representing Quantity: As mentioned, the width of the arrow is indicative of the flow rate, whether it’s in terms of mass, energy, or currency.
Heat or Loss: Channels that are much narrower than others can indicate loss, inefficiency, or waste within the systems they depict.
Hierarchical Structure: Sankey charts often have a hierarchical structure, with inputs at the top, processes in the middle, and outputs at the bottom.

Creating a Sankey Chart:

Creating a Sankey chart requires careful consideration of the objectives and the data. Here is a high-level guide for the process:

Gather Data: Obtain the flow information from the desired system. This information can be complex and require numerous data points.
Identify Channels: Define the system’s components and the channels between them.
Define the Scale: Determine a consistent scale for the flow rates, ideally by normalizing the information or using a logarithmic scale for large data sets.
Build the Skeleton of the Chart: Establish the shape of the channels and their interconnections.
Populate with Data: Introduce the flow data into the channels.
Add Annotations and Labels: Include labels, annotations, and legends to clarify the chart.
Review and Adjust: Look for inconsistencies or irregularities in the chart and adjust where necessary.

There are several software tools that can assist with the creation of Sankey charts, such as Sankey Lab, Power BI, or custom scripts using D3.js.

Applications of Sankey Charts:

The Sankey chart is versatile and can be applied in many areas:

Energy Systems: Analyzing the energy flows within an organization’s energy systems or in larger infrastructure such as power plants.
Process Engineering: Improving processes by highlighting areas of inefficiency or waste.
Environmental Chemistry: Tracking the flow of chemicals during manufacturing and their conversion into end products and waste.
Transportation: Displaying the energy consumed by different modes of transportation and the resulting carbon emissions.
Economic Analysis: Illustrating the flow of money and investment through an economy.
Information Technology: Tracing data flow through information systems to identify瓶颈 (bottlenecks).

Conclusion:

Sankey charts are a compelling visualization tool for mapping the nuanced complexities of various systems. By distilling complex data into a form that is both intuitive and informative, these diagrams enable us to see the underlying structure and patterns of connections. As computational power increases and software tools become more sophisticated, the potential for Sankey chart usage will only grow, making them an invaluable resource for anyone looking to understand and optimize the interlocked world in which we live.

SankeyMaster

SankeyMaster is your go-to tool for creating complex Sankey charts . Easily enter data and create Sankey charts that accurately reveal intricate data relationships.