A SIMPLE DEVICE FOR LABORATORY EXPERIMENTS WITH WATER TABLE CONFIGURATIONS

Experimental laboratory exercises with water table and ground water studies are difficult to conduct. The author has developed a relatively simple device to simulate water table/ground water experiments in the laboratory. The box-like device is constructed of 3/8 inch plywood and measures 36 inches by 36 inches by 18 inches high. The top has an evenly spaced 9 X 9 gridwork of 1.25 inch holes with corresponding holes in a third piece of plywood attached to the inside of the bottom. A set of 81 pieces of ½ inch PVC pipe 20 inches long, with a cap cemented to one end, make up the rest of the equipment.

The experiments are set-up by filling the pipes that have been inserted into the 81 pairs of holes with water to predetermined levels. Water depth in the pipes is measured by inserting a square balsawood stick into the pipe until it floats, then it is removed and the length of wood that was down the pipe is measured. Depths to water are plotted on a 9 X 9 grid of convenient scale and then contoured. After contouring the surface of the water, or other fluid ingredients, an interpretation is made.

A few possible configurations that are easily produced are: a single large cone of depression centered at one corner, a cone of depression centered in the field, a uniformly sloping water table, an injection well. By making pipe lengths longer than 20 inches topography can be simulated to demonstrate the relationship of lakes and streams to a water table. Colors, salts, and “pollutants” may be added to pipes to demonstrate saltwater incursions, “pollutant” plumes, etc. Imagination is the limiting factor with this device.

Students seem to be able to visualize the water table configurations with reasonable accuracy.