Department of Earth Science |Northeastern Illinois University

ESCI 337
Fall, 2005

Daily Objectives #16 (October 31, 2005)                                        Dr. Sanders

Lab #7: Flow nets.

By the end of today's class, you should be able to do the following:

v  Tell what causes ground water to flow in an aquifer.

v  Given piezometer data, determine the total hydraulic head, the elevation head, and the pressure head at a point.

  Use piezometers to determine flow directions in a Darcy tube, and use flow directions to determine relative water levels in piezometers.

  Sketch a cross sectional view of three piezometers that tap an aquifer at different depths, but with their openings in a vertical line.  Sketch the relative positions of water levels in the three piezometers in four situations: Water in the aquifer at that location is  A) flowing downward,  B) flowing upward,  C) flowing laterally (horizontally),  and D) not flowing.

  Define the meaning of the term water table.

v  Sketch flow system maps (flow nets), including the following features in proper relationship to each other.  Explain what each term means.

            a) Flow lines

            b) Equipotential (contour) lines        

            c) Boundaries:  constant head, impermeable (no flow), water table

  Using data from piezometers, draw a flow net in cross section, showing where the water table is.

v  Use a flow net to determine hydraulic gradient, flow velocity, and discharge through an aquifer.

Department of Earth Science | Northeastern Illinois University

© 2005 Laura L. Sanders.  Last updated October 31, 2005.