of Earth Science |Northeastern
Daily Objectives #14 (October
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 Based on hydraulic head measurements from the
piezometers in the ground water flow model, draw a "map" showing flow
through the model. Include the following features:
flow lines showing the direction of flow (put an arrow on the end of
each flow line to tell the direction), contour lines that connect
points of equal hydraulic head, and boundaries to the ground water flow
system. There are three
different types of boundaries to this flow system! Show where
they are, and pay particular attention to how your flow lines relate to
each specific type of boundary.
v From memory, state Darcy's Law.
v Use the results from your Darcy
tube experiment to
estimate the hydraulic conductivity of the sediment in the tube, and
tell whether or not the value is reasonable.
v Demonstrate your understanding of each of the following:
head: Write a definition of hydraulic head, and
tell how it is measured in the lab or field.
piezometer: Point to a piezometer on the Darcy tube,
point to a piezometer on the ground water flow model, find a water
level on a piezometer in the ground water flow model, explain to a
classmate what the purpose of a piezometer is, and use a piezometer on
the ground water flow model to measure hydraulic head at a given point
in the system as you explain to a classmate what you are doing.
Use hydraulic head measurements that you took last class period from
two piezometers to determine the hydraulic gradient in the Darcy tube,
explain how the hydraulic gradient is represented in the Darcy's Law
equation, point out an area of relatively high gradient on your flow
map from the ground water flow model, and point out an area of
relatively low gradient. Tell how your Darcy tube experimental
results would have been different if the hydraulic gradient had been
higher, and give two ways that you could set up the Darcy tube in such
a way as to increase the gradient.
conductivity (K): Explain the meaning of hydraulic
conductivity. Tell how your Darcy tube experimental results would
have been different if the tube had been packed with sediment having a
lower hydraulic conductivity.
head: Explain what is meant by the term constant
head. Explain how head in the Darcy tube experiment was kept
constant during the test. Point to a boundary on your map from
the ground water flow model along which the hydraulic head is constant.
Explain what is meant by the term discharge, and tell how discharge is
represented in the Darcy's Law equation. Give three ways you
could have reduced the discharge in your Darcy tube experiment without altering the construction of the
tube itself. Give two ways you
could have reduced the
discharge in your Darcy tube experiment by altering the construction of the tube
v Sketch a cross sectional view of three piezometers that
tap an aquifer at different depths, butwith 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.
v Determine how you would
flow paths, find hydraulic gradients, and estimate travel times if you had only data from the piezometers
to work with.
v Next up: Using data from
draw a ground water flow map, showing where the water table is.
of Earth Science | Northeastern
© 2005 Laura L.
Last updated October 19, 2005.