To download the following support documentation, check the box of the desired documents and then click the "Download Selected" button. An e-mail will be sent to you with the download links. These documents are available in Adobe Acrobat PDF version 4.0 format.

**UserÂ’s Documentation for MODFLOW-96 (PDF File)**

File Size: 140555 bytes

File Date: Tue Mar 14 05:34:57 2006 This PDF document contains the userÂ’s documentation for MODFLOW-96, an update to the U.S. Geological Survey Modular Finite-Difference Ground-Water Flow Model.

**ProgrammerÂ’s Documentation for MODFLOW-96 (PDF File)**

File Size: 426831 bytes

File Date: Tue Mar 14 05:35:04 2006 This PDF document contains the programmerÂ’s documentation for MODFLOW-96, an update to the U.S. Geological Survey Modular Finite-Difference Ground-Water Flow Model.

**A Modular Three-Dimensional Finite-Difference Ground Water Flow Model (PDF File)**

File Size: 9385088 bytes

File Date: Tue Mar 14 05:30:03 2006 This PDF document contains information about modular three-dimensional finite-difference ground water flow model.

**Download Finite-Difference Ground Water Flow Model Documentation (PDF File)**

File Size: 16851634 bytes

File Date: Tue Mar 14 05:34:54 2006 This PDF document contains the following articles:

- Preconditioned Conjugate-Gradient 2 (PCG2)
- A Method of Converting No-Flow Cells to Variable-Head Cells for the U.S. Geological Survey Modular Finite-Difference Ground-Water Flow Model (BCF2)
- Finite-Difference Interblock Transmissivity for Unconfined Aquifers and for Aquirfers Having Smoothly Varying Transmissivity (BCF4)
- Documentation of a Computer Program to Stimulate Stream-Aquifer Relations Using a Modular, Finite-Difference, Ground-Water Flow Model (STR1)
- Documentation of a Computer Program to Stimulate Aquifer-System Compaction Using the Modular Finite-Difference Ground-Water Flow Model (CHD1)
- Documentation of a Computer Program to Stimulate Horizontal-Flow Barriers Using the U.S. Geological Survey's Modular Three-Dimensional Finite-Difference Ground-Water Flow Model (HFB1)

**MODFLOW 2000 - User Guide to Modularization Concepts and the Groundwater Flow Process**

File Size: 671065 bytes

File Date: Tue Mar 14 05:25:02 2006 This PDF technical document describes a MODFLOW 2000 which is designed to accommodate the solution of equations in addition to the ground-water flow equation. It contains an overview of the old and added design concepts, documents one new package, and contains input instructions for using the model to solve the ground-water flow equation.

**MODFLOW 2000 - Methods and Guidelines for Effective Model Calibration**

File Size: 518307 bytes

File Date: Tue Mar 14 05:24:46 2006 This PDF technical document describes methods and guidelines for model calibration using inverse modeling. The inverse modeling and statistical methods discussed are broadly applicable, but are presented as implemented in the computer programs UCODE and MODFLOWP. UCODE and MODFLOWP perform inverse modeling by calculating parameter values that minimize a weighted least-squares objective function using nonlinear regression. Minimization is accomplished using a modified Gauss-Newton method, and prior or direct information on estimated parameters can be included in the regression. Inverse modeling in many fields is plagued by problems of instability and nonuniqueness, and obtaining useful results depends on:

- defining a tractable inverse problem using simplifications appropriate to the system under investigation and
- wise use of statistics generated using calculated sensitivities and the match between observed and simulated values, and associated graphical analyses

Fourteen guidelines presented in this work suggest ways of constructing and calibrating models of complex systems such that the resulting model is as accurate and useful as possible.

**MODFLOW 2000 - User Guide to Observation, Sensitivity, Parameter-Estimation Processes, and Three Post-Processing Programs**

File Size: 591726 bytes

File Date: Tue Mar 14 05:27:15 2006 This PDF technical document describes the Observation, Sensitivity, and Parameter-Estimation Processes of the groundwater modeling computer program MODFLOW 2000. The Observation Process generates model-calculated values for comparison with measured, or observed, quantities. A variety of statistics is calculated to quantify this comparison, including a weighted least-squares objective function. In addition, a number of files are produced that can be used to compare the values graphically. The Sensitivity Process calculates the sensitivity of hydraulic heads throughout the model with respect to specified parameters using the accurate sensitivity-equation method. These are called grid sensitivities. If the Observation Process is active, it uses the grid sensitivities to calculate sensitivities for the simulated values associated with the observations. These are called observation sensitivities. Observation sensitivities are used to calculate a number of statistics that can be used to diagnose inadequate data, to identify parameters that probably cannot be estimated by regression using the available observations, and to evaluate the utility of proposed new data.

**MODFLOW 2000 - Documentation of the Hydrogeologic-Unit Flow Package**

File Size: 555149 bytes

File Date: Tue Mar 14 05:25:17 2006 This PDF technical document describes the Hydrogeologic-Unit Flow (HUF) Package for the groundwater modeling computer program MODFLOW 2000. The HUF Package is an alternative internal flow package that allows the vertical geometry of the system hydrogeology to be defined explicitly within the model using hydrogeologic units that can be different than the definition of the model layers. The HUF Package works with all the processes of MODFLOW 2000. For the Groundwater Flow Process, the HUF Package calculates effective hydraulic properties for the model layers based on the hydraulic properties of the hydrogeologic units, which are defined by the user using parameters. The hydraulic properties are used to calculate the conductance coefficients and other terms needed to solve the groundwater flow equation. The sensitivity of the model to the parameters defined within the HUF Package input file can be calculated using the Sensitivity Process, using observations defined with the Observation Process. Optimal values of the parameters can be estimated by using the Parameter-Estimation Process. The HUF Package is nearly identical to the Layer-Property Flow (LPF) Package, the major difference being the definition of the vertical geometry of the system hydrogeology. Use of the HUF Package is illustrated in two test cases, which also serve to verify the performance of the package by showing that the Parameter-Estimation Process produces the true parameter values when exact observations are used.

**MODFLOW 2000 - User Guide to the Link - AMG (LMG) Package for Solving Matrix Equations Using an Algebraic Multigrid Solver**

File Size: 806362 bytes

File Date: Tue Mar 14 05:25:37 2006 This PDF technical document describes the Link-AMG (LMG) Package that links MODFLOW 2000 to an algebraic multigrid (AMG) solver for matrix equations. The LMG Package has some distinct advantages over other solvers available with MODFLOW 2000 for problems with large grids (more than about 40,000 cells) and (or) a highly variable hydraulic-conductivity field. Experience has indicated that, in such problems, execution times using the AMG solver are typically about 2 to 25 times faster than execution times using MODFLOWÂ’s PCG2 Package with the modified incomplete Cholesky preconditioner. The drawback to the AMG method used in LMG is the relatively large amount of computer memory required. In problems simulated for this work, the AMG solver used typically required 3 to 8 times more memory than PCG2. For one 465,600-node problem, for example, 151 megabytes (MB) of memory were required when the LMG package was used, whereas PCG2 required 47 MB of memory. The execution time, however, decreased from 942 seconds to 50 seconds, so there is a clear trade-off between execution time and memory requirements. On modern computers, such memory requirements are becoming increasingly attainable.

**MODFLOW 2000 - User Guide to the LMT6 Package, The Linkage with MT3DMS for Multi-Species Mass Transport Modeling**

File Size: 3711908 bytes

File Date: Tue Mar 14 05:27:01 2006 MODFLOW 2000 is a computer program that numerically solves the three-dimensional ground-water flow equation for a porous medium using a finite-difference method. MT3DMS is a computer program for modeling multi-species solute transport in three-dimensional groundwater systems using multiple solution techniques, including the finite-difference method, the method of characteristics (MOC), and the total-variation-diminishing (TVD) method. This PDF technical document describes a new version of the Link-MT3DMS Package, which enables MODFLOW 2000 to produce the information needed by MT3DMS, and also discusses new visualization software for MT3DMS. Unlike the Link-MT3D Package that coordinated previous versions of MODFLOW and MT3D, the new Link-MT3DMS Package requires an input file that, among other things, provides enhanced support for additional MODFLOW sink/source packages and allows list-directed format for the flow model produced flow-transport link file.

This PDF technical document contains four parts:

- documentation of the Link-MT3DMS Package Version 6 for MODFLOW 2000
- discussion of several issues related to simulation setup and input data preparation for running MT3DMS with MODFLOW 2000
- description of two test example problems, with comparison to results obtained using another MODFLOW-based transport program
- overview of post-simulation visualization and animation using the U.S. Geological SurveyÂ’s Model Viewer.

**User's Guide for MODPATH/MODPATH-PLOT, Version 3**

File Size: 817156 bytes

File Date: Tue Mar 14 05:35:19 2006 This PDF technical document describes MODPATH/MODPATH-PLOT. MODPATH is intended for general use and may have to be modified by the user for specific applications. The methods used by MODPATH are based on specific assumptions that result in limitations that must be thoroughly understood to obtain meaningful results.

MODPATH is a particle tracking post-processing package that was developed to compute three dimensional flow paths using output from steady-state or transient groundwater flow simulations by MODFLOW. The particle tracking package consists of two FORTRAN computer codes:

- MODPATH, which calculates particle paths
- MODPATH-PLOT, which displays results graphically

**Download Documentation and User's Guide for MT3DMS (PDF File)**

File Size: 2077777 bytes

File Date: Mon Mar 5 07:57:58 2007 This PDF file contains documentation and a user's guide for MT3DMS: a modular three-dimensional multispecies transport model for simulation of advection, dispersion, and chemical reactions of contaminants in groundwater systems.

**Download RT3D User Manual (PDF File)**

This report describes the mathematical details of the RT3D computer model and its input/output data structure.

**Download RT3D Version 2.5 Update Document (PDF File)**

This report describes what's new in RT3D version 2.5.

**SEAM3D v3.0 - Documentation and User's Guide**

This PDF technical document provides documentation on SEAM3D. The focus of this document is two new modules to the SEAM3D code: the Chlorinated Ethene, and Cometabolism Packages. Included in this document are model and code verification exercises for the new modules and an application of the code to a field problem.

This PDF technical document describes UTCHEM, a 3-D, multicomponent, multiphase, compositional model of chemical flooding processes which accounts for complex phase behavior, chemical and physical transformations and heterogeneous porous media properties, and uses advanced concepts in high-order numerical accuracy and dispersion control and vector and parallel processing.