This video illustrates the process of drawing a groundwater flow net. The flow net represents groundwater flow below a dam from a headwater reservoir on the left to a tailwater reservoir on the right. A cutoff wall protruding below the base of the dam increases the flow path below the dam, decreasing the flow velocity, thus reducing the potential for the groundwater flow to erode the porous material at the toe of the dam.

The video is part of the supplemental material to the book Graphical Construction of Groundwater Flow Nets by Eileen Poeter and Paul Hsieh. This book is published by The Groundwater Project and can be downloaded at no cost by visiting https://gw-project.org.

The mission of The Groundwater Project is to provide accessible, engaging, high-quality, educational materials, free-of-charge online in many languages, to all who want to learn about groundwater and understand how groundwater relates to and sustains ecological systems and humanity. Learn more about the Project at https://gw-project.org.