Understanding Groundwater Contamination: Session 9 Introduction to Groundwater Modeling

You will not learn how to do groundwater modeling in this webinar. You may learn something about evaluating groundwater model report.
What is a groundwater model?
It is a simplified representation of a groundwater situation used to explain the past, corroborate the current, and/or predict the future.
A model can answer questions like How did this happen? Who is responsible? What will happen in the future? How long will "it" take?

What is a groundwater model?
1. Simplified representation of a groundwater situation to explain the the past, corroborate the current, and/or predict the future
2. A model can answer questions like: How did that happen? Who is responsible? What will happen if....and How long will it take to...

First step in groundwater modeling First, define the objectives of your model, e.g., with another well, will there be enough groundwater to supply this community. If we add another well will it dry out the stream? Who is responsible for the groundwater contamination? Why is the groundwater level falling? Are there enough to capture the contamination in the groundwater plume? When will the contamination reach the wells? What will contamination level be at the well in 30 years.

Second, develop a conceptual site model (CSM). A CSM is a simplified summary of all information needed to go into the model (geology, hydrogeology, pumping recharge, boundary conditions and more).

Third, select the model code - groundwater flow or chemical transport, dissolved contaminants or chemical phase? unsaturated flow? How do you want to simulate dissolved chemical movement? Advection (particle tracking) or advection and dispersion (plume development / concentrations). How many dimensions are important and why (1D, 2D, 3D)? Steady state or transient? Numerical or analytical model? Which models will serve you best? Use models readily accepted by the court or regulators (models developed by USGS or the USEPA).

Fourth, Model Design Conceptual model and data - numeric model. Discretize - overlay grid on conceptual model. Assign hydraulic conductivity