This webinar excerpt explores how contaminants move through groundwater and provides a mental framework for understanding subsurface pollution. Since groundwater contamination is hidden beneath the surface, visualizing it is often challenging. This presentation enhances conceptual understanding by using a water-saturated sand tank experiment to demonstrate the flow and transport mechanisms of contaminants in groundwater.

The experiment illustrates key hydrogeological concepts, including:

• Groundwater Flow Direction – Determined by water table gradients.
• Aquifers and Aquitards – Differentiating between confined and unconfined groundwater zones.
• Contaminant Transport Processes – Including advection (movement with groundwater flow) and dispersion (spreading laterally and vertically).
• Dye Injection as a Contaminant Analog – Showing how pollutants enter and migrate through the subsurface over time.
• Visualization Methods – How contamination is typically represented using concentration contours, color gradients, and plume mapping techniques.

Through this hands-on demonstration, viewers will gain a clearer mental model of groundwater pollution, an essential skill for environmental scientists, engineers, and professionals working in groundwater contamination analysis.

This video is an excerpt from the seminar “Introduction to Groundwater Contamination”, presented to the UC Berkeley Department of Civil and Environmental Engineering in September 2021.

Citation: Source of laboratory experiment screenshots: “https://www.youtube.com/channel/UCiOt82uaRA7E5QRsL27cVFA”

Subsequent images of lab experiment are adapted screenshots of the same YouTube video.