Ground-Water-Simulation Apparatus for Introductory and Advanced Courses in Environmental Geology

We have developed a new advanced hydrogeology pollutant-transport simulation apparatus that is widely adaptable and can be used for quantitative experiments. It allows students to readily observe processes that are otherwise unobservable because of temporal and spatial constraints and because they take place in the subsurface. The simulator is a gently inclined, 61 cm × 122 cm terrarium with input and outflow ports on either side. The terrarium is filled with layers of sand and clay to simulate stratigraphy. “Wells” are simulated by clear plastic tubes with screened ports that are spaced at regular intervals and depths. In one experiment, water-based dye is injected as a plume in the top center of the terrarium, creating a slug that moves down the gradient towards the wells. Groups of students pipette samples from the wells at regular intervals and qualitatively estimate dye concentrations using a color-tone calibration set. Flow models and time-integrated displays of plume concentrations can be constructed. A second experiment involves measuring water height in the wells and constructing a flow net for the system using a computer program.