Department of Earth Science |Northeastern Illinois University
Daily Objectives #13 (October 11, 2007)                                        Dr. Sanders

 By the end of today's class, you should be able to do the following: v Flow Nets Read hydraulic head values in piezometers and use them to construct a flow net. Tell what the angular relationship is between flow lines and equipotential lines (hydraulic head contours). Identify boundaries to a flow system: no-flow (impermeable) boundaries water table boundary constant head boundaries constant flow boundaries (rarely used in modeling natural systems). For the first three types of boundary listed above, tell the relationship of flow lines to that boundary.  Then tell the relationship of equipotential lines (hydraulic head contours) to that boundary. List the steps to follow in drawing a flow net, and demonstrate that you know how to follow them. Use a flow net to calculate discharge through a segment of earth material such as an aquifer or aquitard. v Darcy's Law Use Darcy's Law to calculate flow through an area illustrated on a cross sectional flow net. v  Properties of Porous Materials Explain what the specific yield tells us about how much water can drain from a volume of rock or sediment. Apply the definition of specific yield to a given area to calculate water quantities that can be drained.

Today's Agenda:

v Flow Nets and Darcy's Law
• On your flow net, be sure to include flow lines and hydraulic head contours (equipotential lines).  Label the contour lines with their hydraulic head value.  Use a consistent contour interval!  Put arrows on the flow lines to show direction of flow.
• Construct a flow net on Figure 4.20 from your textbook, and identify any boundaries that appear on it.  Use it to solve Problem 17 in that chapter.
• Construct a map-view flow net on Figure 3.32 from your textbook, and identify any boundaries that appear on it.  Use it to solve "Analysis b" on p. 109 of your textbook.
v  Properties of Porous Materials
• Solve the final problem on the exam, using specific yield to calculate volume of water that would be drained from a given area to a given depth.

© 2007 Laura L. Sanders.  Last updated October 11, 2007.