4.1 Groundwater flow models are tools frequently applied for the analysis of hydrogeologic systems. Due to the significance of many decisions based upon modeling results, quality assurance measures need to be applied to model applications. Complete model documentation is a mechanism to ensure the quality of the effort.

4.2 Several federal and state agencies have developed policies regarding model documentation. This guide provides consistency amongst current policies, and should be used as a framework for model documentation.

1.1 This guide covers suggested components to be included in documenting and archival of numerical groundwater flow model applications. Model documentation includes a written and graphical presentation of model assumptions and objectives, the conceptual model, code description, model construction, model calibration, predictive simulations, and conclusions. Model archival refers to a file or set of files (in both written and digital format) that contains logs of significant model simulations (that is, calibration, sensitivity and prediction simulations), supplemental calculations, model documentation, a copy of the model source code(s) or executable file(s) used, or both, and input and output data sets for significant model simulations.

1.2 This guide presents the major steps in preparing the documentation and archival for a groundwater flow model application. Additional information on groundwater model documentation can be found in EPA-500-B-92-006. ²

1.3 This guide is specifically written for saturated, uniform density, groundwater flow model applications. The elements presented for documentation and archival are relevant and applicable to a wide range of modeled processes (in and out of the realm of groundwater flow) and can be tailored for those applications.

1.4 This guide is not intended to be all inclusive. Each model application is unique and may require supplementary documentation and archival.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

1.6 This guide offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project's many unique aspects. The word Standard in the title of this document means only that the document has been approved through the ASTM consensus process.