What can you do in the lab for $100??
What if you don't have big bucks to buy equipment for students to use in a hydrogeology course? The participants at the 2005 workshop Teaching Hydrogeology in the 21st Century assembled ideas for inexpensive but effective demos to use in the lab and class with students.
Using a Carboy to Illustrate a Water Budget
- Purpose: a simple demonstration to illustrate inflow (precipitation), multiple outflows, and change in storage.
- Description: Carboy filled about half way with water with four holes drilled below water level. A tube in each hole has a small valve to control flow rate out of the tube. Water flowing in from the sink represents precipitation, and the tubes represent outflows that can be varied independently. Change in water level in the carboy represents change in storage. Tim Callahan (College of Charleston) and David Boutt (University of Massachusetts, Amherst). Download a diagram. ( PRIVATE FILE 273kB Jul27 05)
- Purpose: an apparatus to illustrate components of hydraulic head.
- Description: Plexiglass cylinder packed with sand with inflow and outflow ports at the ends and a manometer installed at each end in the sand. The manometers are connected to Tygon tubes, which are attached vertically to a board marked with a reference scale. Pressure head and elevation head components are shown by the height of the water level in the two tubes. Tim Callahan (College of Charleston). Download a diagram. ( PRIVATE FILE 265kB Jul26 05)
An Alternative Darcy Column
- Purpose: an apparatus to illustrate Darcy's Law and hydraulic conductivity.
- Description: An alternative construction technique involves three pieces of 1" acrylic tubing, the first piece of tubing arranged under a faucet and acting as the inflow. This is connected by Tygon tubing and rubber stopper to the second tube, which is packed with sand. The second tube is connected to the third in similar fashion and arranged vertically against a ruler. Keeping head constant in tubes one and three, the flow rate is measured by determining the outflow through a hole in the stopper in tube three. Daria Nikitina (California University of Pennsylvania), Martin Helmke (Dickinson College), and Dick Enright (Bridgewater State College).
Lab-scale Advection/Dispersion Demonstration
- Purpose: to measure the Darcy velocity of the water flowing through sand and to demonstrate dispersion of a tracer flowing through the sand.
- Description: Tank (aquarium) filled with sand with a screened well in the middle and reservoirs on each end, one for input and one for outflow. Constant head is maintained by overflow pipes at different levels on the input and outflow sides. A saltwater tracer and conductivity probe are added to the well and monitored over time. Conductivity at the outflow is also measured over time. Todd Rayne (Hamilton College), Vitaly Zlotnik (University of Nebraska, Lincoln), Kamini Sinha (Stanford University), Tom Brikowsky (University of Texas at Dallas), Paul Ryberg (Clarion University), and Kurt Friehauf (Kutztown University). Download a diagram. ( PRIVATE FILE 348kB Jul26 05)
Contaminant Transport Demonstration with Tracer Breakthrough
- Purpose: an apparatus to demonstrate the concept of dispersion of a tracer (in this case salt) as it moves through water-saturated sand.
- Description: Two plastic tanks connected with a sand-filled PVC tube. Adding water to both tanks and maintaining higher head in one tank than the other causes flow through the tube. After adding concentrated salt water to the tank with the higher head and mixing thoroughly, electrical conductivity is measured over time in the second tank. Constant head is maintained by adding fresh water to the first tank and allowing water to drain from the second tank. Jeane Pope (DePauw University), Tim Eaton (Queens College, CUNY), and LeeAnn Munk (University of Alaska, Anchorage). Download a diagram. ( PRIVATE FILE 134kB Jul26 05)
Stream/Groundwater Interaction Model
- Purpose: to demonstrate the interaction between groundwater and surface water in a stream.
- Description: Inclined plexiglass tank with a layer of sand on the bottom. A channel cut in the sand layer is lined with perforated PVC pipe cut in a half cylinder and sandwiched with a fabric layer, which allows demonstration of either a gaining or losing stream. Stan Galicki (Millsaps College), Aaron Johnson (UVA's College at Wise), Laura Rademacher (Cal State, LA), Carl Renshaw (Dartmouth College), Jay Sims (Univ. of Arkansas, Little Rock), and Matt Uliana (Texas State, San Marcos). Download a diagram. ( PRIVATE FILE 499kB Jul27 05)
Analog Model for a Fractured Aquifer
- Purpose: a model to demonstrate the movement of contaminants through networks of fractures.
- Description: A fracture sheet of gypsum wallboard sandwiched between sheets of plexiglass with spot sources of dye (simulated contaminants). Adding water to the model spreads the dye, modeling the spread of contaminants in a fractured aquifer. Horacio Ferriz (Cal State, Stanislaus), Don Siegel (Syracuse University), Solomon Isiorho (Indiana Univ.—Purdue Univ., Ft. Wayne), Tom Lachmar (Utah State Univ.), Joe Yelderman (Baylor Univ.), and Devin Castendyk (SUNY Oneonta). Download a diagram. (Microsoft Word PRIVATE FILE 44kB Jul27 05)
Analog Model of an Earth Dam
- Purpose: a model to demonstrate the geometry of the water table across an earth dam.
- Description: Model of a clay-cored earth dam sandwiched between sheets of plexiglass. Horacio Ferriz (Cal State, Stanislaus), Don Siegel (Syracuse University), Solomon Isiorho (Indiana Univ.—Purdue Univ., Ft. Wayne), Tom Lachmar (Utah State Univ.), Joe Yelderman (Baylor Univ.), and Devin Castendyk (SUNY Oneonta). Download a diagram. (Microsoft Word PRIVATE FILE 41kB Jul27 05)
Tension Saturated Zone (Capillary Fringe) Demonstration
- Purpose: to demonstrate that water held in the capillary fringe fills all the pores but is held at slightly less than atmospheric pressure. Addition of a small amount of water converts this zone to a saturated zone.
- Description: Plexiglass column or clear bucket filled with very fine sand or silt and with an outlet drilled below the top of the sand. With the model filled with water so that the water table lies below the outlet, spraying the surface of the sand with colored water causes clear water to flow out the outlet. Jim Reichard (Georgia Southern University). Download a diagram. ( PRIVATE FILE 333kB Jul26 05)
A Cheap Permeameter
- Purpose: an apparatus to demonstrate Darcy's Law and to determine hydraulic conductivity of sediment samples.
- Description: Clear PVC/acrylic tube packed with sand, a plug on each end, and tubing on each end through the plugs with valves on each tube. Martin Stute (Barnard College) Download a diagram. ( PRIVATE FILE 242kB Jul27 05)
Peanut Butter Jar Porosity
- Purpose: to demonstrate that porosity is a function of grain sorting, not of grain size.
- Description: Three peanut butter jars, one filled with marbles, one filled with to an equal level with BBs, and one filled to an equal level with a mixture of marbles and BBs. The amount of colored water added to each jar allows quantification of porosity. Larry Lemke (Wayne State University). Download a diagram. ( PRIVATE FILE 271kB Jul27 05)
Hydraulic Conductivity and Specific Yield Demonstration
- Purpose: a simple device to determine hydraulic conductivity and specific yield and to do tracer tests.
- Description: Acrylic tube filled with sand and clamped vertically to a ring stand. Two tubes, one as a drain tube and one with a manometer, come out of the bottom and are controlled separately by valves. Hydraulic conductivity is determine by using the tube as a permeameter. Specific yield is determined by adding water and letting it drain out by gravity. A tracer test can be done by adding a tracer, such as salt water, and monitoring electrical conductivity in the catchment container. Anne Veeger (University of Rhode Island) and Maddie Schreiber (Virginia Tech). Download a diagram. ( PRIVATE FILE 209kB Jul27 05)
Measurement of Porosity, Specific Yield, and Specific Retention
- Purpose: a device to measure porosity, specific yield, and specific retention.
- Description: Clear plastic tube filled with "aquifer protolith" (marbles) and connected to Tygon tubing that comes out the bottom and is connected to a burette clamped vertically to a ring stand. Volume of pores can be determined by emptying the burette repeatedly into the tube until the pore spaces are filled. Specific yield and specific retention can then be determined by gravity-draining the tube into a graduated cylinder and calculating yield and retention.