7. Environmental Modeling

Environmental models are often used to describe the transport of contaminants when measurements are not possible—for example, in predicting future events. Models can be computer simulations or napkin-back equations. Using either requires an understanding of the simplifications made to the governing equations and to the many required input-, boundary-, and initial-condition parameter values. Model calibration involves setting realistic parameter values until the model output matches reasonably well with a set of measurement data. Model validation involves matching the model output to a second set of data using the calibrated parameter values. Packaged models exist for many environmental settings, including surface water, groundwater, river sediments, air, soil vapor, and indoor air.