STELLA Systems Modeling

Jonathan Levy and Larry Mayer


from esselearnmod.html STELLA-based modeling can be used to teach about equilibrium versus kinetic reactions and thus allows one to examine the implications of nonequilibrium systems. In this exercise, students use STELLA to model an aquifer/ground-water-contaminant system. They conceptualize the sorption system, build a diagram to represent their conceptualization, and convert their diagram to a quantitative and executable model. The system is initially out of equilibrium and the students must run it to equilibrium. Throughout the process, students explore the system and discover connections among model parameters, initial conditions, and resulting changes in concentrations.

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Learning Goals

  • Use computer programs to allow students with minimal calculus skills to explore the nature and implications of Earth systems and their mathematical relationships.
  • Test hypotheses and make predictions.
  • Strengthen students mathematical skills.
  • Gain a greater understanding of Earth systems and chemical equilibria.

Context for Use

This activity is appropriate for upper-level undergraduate and graduate-level hydrogeology and geochemistry courses.

Description and Teaching Materials

The following materials are required:
  • STELLA II, a computer modeling application available in both Macintosh and IBM formats.

Teaching Notes and Tips

This activity can be adapted to model various chemical and biological reactions and systems in lower and upper-level undergraduate and gradtuate-level geoscience courses.


STELLA adds an active, demanding, and rewarding component to teaching and learning various Earth system concepts.

References and Resources

Levy, J. and Mayer, L., 1999, Systems Modeling of Nonequilibrium Chemical Reactions Using STELLA, Journal of Geoscience Education, v. 47, p. 413