Department of Earth Science |Northeastern Illinois University

Review Sheet for Exam #1 (October 4, 2007)                                        Dr. Sanders

Exam #1 is open-note, open-book.  You may bring any printed materials you like.  You should be able to do the following:

v Write the full names of at least two of your classmates.

v Making Hydrogeologic Calculations:
• Describe the purpose and function of a rain barrel, and make quantitative calculations to estimate how a rain barrel is involved in the water budget of a residential property in Chicago.   The information you need is on this PowerPoint presentation (5.2MB).  Make all the calculations required to answer questions on the slides with white backgrounds.
• Use concepts of length, area, volume, and flow rate to quantify hydrologic variables.
• Solve a hydrologic problem in a sequence of logical steps, using reasonable units and dimensional analysis.
v Wells and Ground Water Systems:
• Measure depth to water in a well and the total depth of the well.   Extract water from the well and describe the effect of that extraction on the water level over time.  Sketch a diagram illustrating the components of a well.  Develop a test protocol for evaluating how a well responds to pumping.  Information on what we are doing outdoors appears at this link.
v Water Flow:
• Using the ground water flow model, inject dye into the model and track its flow through time.  Sketch a diagram showing the following features:
q surface water

q    ground water
q boundaries of the flow system
q flow directions (use arrows)
q flow velocities (show areas of fast/medium/slow flow) (Note: we did not debrief this item, and the data were inconsistent; we'll come back to this activity in a few weeks.)
• Describe in words what makes water flow.  Using simple sketches, show how water would flow from one container (like a rain barrel) into another if they were connected by hoses.
v Water Flow--Lab Explorations: Investigate, discover, and articulate the general principles that describe the movement of water and the factors that drive it.  Use simple lab set-ups to investigate the movement of water through open conduits and through porous media.

Activities
• Bucket-to-Bucket Transfer
• Holey Water Bottle
• Draining Work
• Capillary Action
• Infiltration Observation
• Darcy Discovery
Follow-up questions (these were assigned  for Homework #2):
• What is the effect of tube diameter on flow velocity in Bucket-to-Bucket transfer?
• What is the effect of grain sorting on how much water drains out of sediment in Draining Work?
• What is the effect of volume of water in the upper bucket on flow rate in Bucket-to-Bucket transfer?
• What makes the water flow in Bucket-to-Bucket transfer?
v Properties of Porous Materials:
• Define the following terms, using appropriate units of measurement:
• porosity
• effective porosity
• specific yield
• specific retention
• hydraulic conductivity
• permeability
• Write formulas defining each of the properties.  Write a formula that relates specific retention and specific yield to porosity.
• Explain the difference between hydraulic conductivity and permeability.
• Characterize rocks and sediments in terms of their porosity, effective porosity, specific yield, and specific retention, giving typical ranges of values of these properties for each type of rock and sediment.
• Define the terms aquifer and aquitard.
• Define the term hydraulic head and describe its two components.
• Explain the effect hydraulic head has on the flow of water.
• Discuss what makes water flow and how that relates to the concept of hydraulic head.  Determine the hydraulic head at various points in a cross section illustrating a shallow ground water system.   (Click here to get the worksheet.)
• Determine the hydraulic head within a bucket of water.  (Hint: you will need to start by setting an arbitrary datum.)
• <>If two buckets are connected by a tube (see a simple worksheet here), find the total hydraulic head at each end of the tube.  What does this tell you about direction of flow?  What if the end of the tube is higher than water level in the lower bucket?  What happens if the tube is made longer?  Looped?  Made shorter?  Packed with sand?
• <>Given a system of two water buckets with a tube between them (see the worksheet here), say whether water will flow from one bucket to the other (and if so, which way).  Come up with a general rule that tells whether water will flow or not and if so, which way.
• Return to the system of two buckets connected by a long tube, the tube packed with sand.  Find the hydraulic head at a point exactly halfway between the two ends of the tube, and at points exactly one-fourth of the way from each end.   Then, consider a shorter tube packed with sand, but starting and ending at the same places as the longer one.  Find the hydraulic head at the 1/4, 1/2, and 3/4 points.  How is this system like/unlike the system with the longer tube?  Explain the term hydraulic gradient.
v Water Table:  Discuss the meaning of the following terms:
• water table
• saturated (phreatic) zone
• capillary zone (capillary fringe)
Explain how each of the above relates to atmospheric pressure and pressure of water in pores (pore water pressure), and describe saturation conditions in each of the zones.  Tell what the hydraulic head is at a point directly on the water table.

v Measuring Hydraulic Conductivity and Permeability:
• Devise a new protocol for measuring hydraulic conductivity (see Homework #3).  Using that protocol, measure the hydraulic conductivity of two samples of sediments, and write a lab report as per the instructions  given on the homework page.
• Draw a sketch of your experimental set-up.  Determine the hydraulic head at these two points: as water enters the sediment sample, and as it exits the sediment sample.  Find the hydraulic gradient within the sample.  How could you have increased discharge (Q) through the sample by altering your experimental set-up?
v Darcy's Law:
• Formulate a way to combine hydraulic conductivity, cross sectional area, and hydraulic gradient to give the discharge of water flowing through a tube packed with sand.  Check to be sure the units of measurement work out!  Find a statement of Darcy's Law in your textbook, and tell how it compares with what you just formulated.

Department of Earth Science | Northeastern Illinois University

© 2007 Laura L. Sanders.  Last updated October 2, 2007.