Open-File Report 2006–1104

U.S. GEOLOGICAL SURVEY
Open-File Report 2006–1104

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Model Output

For DVRFS model simulations, MODFLOW-2000 generates two listing output files (as specified in the name file). Most of the output from the GWF and SEN Processes is written to the LIST file, while output that applies to the overall model simulation is written to the GLOBAL file. The LIST file includes allocation information, values used by the GWF Process for layers and individual cells to solve the flow equation, and calculated model results such as hydraulic head, drawdown, and the water budget. When the OBS Process is active, the LIST file also contains the model-calculated equivalents to the observations and the related statistics. When the PES Process is active and a new iteration begins, the LIST file is erased and regenerated. As a result, most of the GWF and SEN Process output is limited to that produced during the most recently executed parameter-estimation iteration.

The GLOBAL file contains information that applies to the model simulation as a whole. This output includes the names and types of all input files. Input for the GLO Process is echoed in the GLOBAL file. The GLOBAL file includes spatial and temporal discretization, and solver information. The GLOBAL file also contains parameter definitions read from the various packages that define boundary conditions and stresses for the GWF Process. Input from active OBS, SEN, and PES Processes is echoed to the GLOBAL file. If the OBS, SEN, and PES Processes are all active, the GLOBAL output file contains:

  1. Information about the array storage needed by the OBS, SEN, and PES Processes.
  2. Information about the definition of parameters and observations.
  3. Observation-sensitivity tables produced using the starting parameter values. Observation sensitivities include dimensionless scaled sensitivities and composite scaled sensitivities, and (or) one-percent scaled sensitivities.
  4. Parameter values and other information from each parameter-estimation iteration.
  5. Observation sensitivity tables produced using the final parameter values.
  6. Parameter variance-covariance and correlation matrices.
  7. Parameter confidence intervals.
  8. A comparison of the parameter values and user-defined reasonable upper and lower limits of the parameter value.
  9. Summary statistics about the model fit to the observations.

The LIST output file contains:

  1. Information about the array storage needed by each GWF Process Package.
  2. Printed arrays of heads for the entire model grid. The printed arrays depend on the contents of the GWF Process, BAS6 Package, and OC Option.
  3. Tables that list observed and simulated values from the latest set of parameter values.
  4. Observation-sensitivity tables calculated using the most recently calculated grid sensitivities. Possibilities include dimensionless scaled sensitivities, composite scaled sensitivities, and (or) one-percent scaled sensitivities.

Additional output files are produced by the OBS Process (table 5). These files are designed for use by plotting routines and other programs (Harbaugh, 1990; Hanson and Leake, 1999; Winston, 2000). Output files are named using a file name base, defined by the user in the OBS Process variable OUTNAM. Files are named as OUTNAM followed by a period and an extension that begins with an underscore. For example, if OUTNAM is “dvr”, the output file names are “dvr._os” and so on. These files are collectively referred to as the “underscore” output files.

In all “underscore” output files (dvr._* files) produced when the OBS Process is active (table 5), the plot symbol variable (PLOT-SYMBOL) is used to identify an observation as either a head observation (PLOT-SYMBOL is 0 or 1), a head-change observation (PLOT-SYMBOL is 2, 3, or 4), a discharge observation (PLOT-SYMBOL is 3), or a constant-head flow observation (PLOT-SYMBOL is 3) (table 6). Although the PLOT-SYMBOL value of 3 is used for head change, discharge, and constant head flow observations, the observation type can be easily identified from the observation name (variable OBSNAM). Numeric OBSNAMs indicate head change observations; alphabetic OBSNAMs indicate constant-head boundary flows and discharge observations. Furthermore, for constant-head flow observations, the OBSNAM begins with “C_”. For discharge observations, the OBSNAM begins with “OBS” for steady-state observations, “OB” for observations in the stress period representing 1960, and “O” for observations in the stress period representing 1998.

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