In Reply Refer To: March 22, 2005
Mail Stop 411
OFFICE OF GROUND WATER TECHNICAL MEMORANDUM NO. 2005.02
Subject: PUBLICATIONS--Policy on documenting the results of new simulations using previously published ground-water models
The Office of Ground Water has received numerous inquiries about the appropriate level of documentation required for additional numerical simulations made using a previously published ground-water model (a flow or transport model). The existing policy on documenting the development of a ground-water model in project reports is stated in Office of Ground Water Technical Memorandum No. 96.04 (http://water.usgs.gov/admin/memo/GW/gw96.04.html). However, if a ground-water flow or transport model has already been developed and documented in a published report to aid in solving a previous problem, that model may be useful in addressing new questions raised by our cooperators in managing their resources. The documentation required for additional numerical simulations made using a previously published ground-water model follows the intent of the original policy but can be condensed. In this memorandum, “original model” refers to a model that was previously developed and documented in a published report, and “scenario model” refers to new model simulations using a previously developed, documented, and published ground-water model. As used here, scenario model results are based on new stresses, such as the simulation of additional wells, pumping rates, or chemical sources that differ from the original model. A scenario model does not involve major changes to the structure of the original model (such as changing the grid, boundary conditions, transmitting properties, or transport properties used in the model), which would require substantial documentation and recalibration of the original model.
Scenario model simulations must be documented in a published report to ensure
that the simulations are appropriate for the model, the stresses applied in
the simulations are fully described, and the results are available to the public
on an equal basis. Models always involve simplifications and are developed
to answer specific questions. The appropriateness of the model to address new
questions must be evaluated and described in the report. In addition, as stated
in Water Resources Division Memorandum No. 94.19, “Longstanding USGS
policy requires that information be released to all interested parties (the
public) on an equal basis, and that no interpretive information be released
to the public without prior approval of the Director.” This requirement
to publish new findings is reiterated in the U.S. Geological Survey Manual
(http://www.usgs.gov/usgs-manual/500/500-14.html) and in Office of Water Information
Technical Memorandum No. 2002.11 on “Reemphasizing the importance of
public release of investigation results”
(http://water.usgs.gov/usgs/publishing/Memos/memo2002_11.html).
In documenting scenario model results, only the aspects of the original model that are changing or are particularly relevant to the discussion of the adequacy of the model to simulate the new stresses need be described in the report. A complete re-documentation of the original model construction is not necessary. The original model can simply be referenced in the scenario model report. All the details of the construction and calibration of the original model need not be reproduced in the new report documenting the scenario model results. The main components of a scenario model report are:
In addition, the scenario model must be archived in accordance with Office of Ground Water Technical Memorandum No. 00.02 on the archiving of models (http://water.usgs.gov/admin/memo/GW/gw00.02.html).
In many cases, reports documenting scenario models can be relatively short and concise, and can be released online-only, if desired. These reports, whether online-only or printed, must address the critical elements listed above, and they must go through the complete USGS report review and approval process.
William M. Alley /s/
Chief, Office of Ground Water
Distribution: A, B, S, FO, PO,
Regional and District Ground Water Specialists, NR, CR, SR, and WR