Types of Models

The U.S. Geological Survey Toxics Substances Hydrology Program uses and develops the following types of models.

Simulation Models

Simulation models represent the physical, chemical, and biological processes that control the movement and fate of toxic substances in the hydrologic cycle. These models are used as tools to quantify process rates; determine persistence of environmental contamination and feasibility of natural cleanup alternatives; and design containment and remediation strategies, monitoring networks, and waste-disposal facilities. Examples include models that simulate:

(1) the movement of dissolved contaminants in ground water,
(2) the movement of contaminants as vapor in the subsurface, and
(3) geochemical and biological reactions involving multiple contaminants.

The models are tested at the field sites to confirm their validity and applicability.

Statistical Models

Statistical models are developed to relate information regarding contamination occurrence and variables related to factors that may influence occurrence. Although these models imply no cause-and-effect relationship, they provide valuable insights into the circumstances under which contamination is found.

Additional Information

• Information on Models and Applications

Bibliographies

• Modeling Tools and Modeling Applications