Department of Earth Science |Northeastern Illinois University

ESCI 337
Fall, 2007

Daily Objectives #21 (November 8, 2007)                                        Dr. Sanders

By the end of today's class, you should be able to do the following:
v Ground Water Modeling: Practice
  • Explain what the results of your model are (i.e. tell what the direction of flow is, and how pumping affects the flow system).  Review
  • Explain/defend the results of your model, telling if/why it is a reasonable representation of the flow system.  Review
  • Explore what happens to the modeled flow systems when you change values for variables.  Review
  • Perform a "sensitivity analysis" for your model.

Today's Agenda:

v Ground Water Modeling: Evaluating the Model

(Continued from last time) How good is your model?  First, apply the "Is this reasonable?" test.  Does it show water flowing in what appears to be a reasonable direction?  Are there good reasons for the gradients to be as indicated on the map?  Does the five-year recharge area look reasonable?

Second, try changing some variables and see what happens to the five-year recharge area. 
Consider how good your estimates are.  How reliable is your estimate of, for example, hydraulic conductivity?  Could the actual value reasonably be higher?  Lower?  By how much?  Change the values and re-run the model; see how the results differ.  Here are some suggested approaches: Finally, do a "sensitivity analysis": Now that you know the effect of changing each variable, rate its effect as "strong", "moderate", or "minimal".   You may wish to use the document attached here as an aid to organizing your results

Department of Earth Science | Northeastern Illinois University

© 2007 Laura L. Sanders.  Last updated November 8, 2007.