MODFLOW-96 Data Requirements
Date requirements for visualizing MODFLOW-96 results are as follows:
- The user must create a text file that specifies the elevation of layers
in the MODFLOW-96 model grid. This file is not need for running MODFLOW-96, but is
needed by Model Viewer. How to make the layer elevation file.
- The input parameters
HNOFLO and
HDRY must be
assigned values that are different
from simulated heads at active cells. (See note 1 below.)
- Simulated heads (for all
model layers) must be saved to file at one or more stress periods/time steps. The
head file may be formatted or unformatted. (See note 2 below.) For a formatted file, the input parameter
CHEDFM
in the output control (OC) file should include the word LABEL.
- To view drawdown results,
drawdown (for all model layers) must be saved to file at the
same stress periods/time steps as the saved heads. The drawdown file may be formatted
or unformatted. (See note 2 below.) For a formatted file, the input parameter
CDDNFM
in the output control (OC) file should include the word LABEL.
- To view compaction simulated by the Interbed Storage (IBS) package, compaction must be saved to file
at the same stress periods/time steps as the saved heads. Note that the compaction file
generated by MODFLOW-96 is unformatted.
- To view critical heads simulated by the IBS package, critical head must be saved to file
at the same stress periods/time steps as the saved heads. Note that the critical head
generated by MODFLOW-96 is unformatted.
- To view specific discharge vectors, cell-by-cell flow
terms for the Block-Centered Flow (BCF) Package must be saved to file at the same stress
periods/time steps as the saved heads. The cell-by-cell flow data may be
in compact or noncompact form. Cell-by-cell flow terms for other packages may
be saved to the same file. Model Viewer will ignore these data. Note that the
cell-by-cell flow file generated by MODFLOW-96 is unformatted.
Notes:
- If the simulated head at a cell is equal to either
HNOFLO or HDRY, Model Viewer assumes that the cell is inactive and will not
display it. Therefore, the common practice of setting HNOFLO or HDRY to
zero should be avoided if heads at active cells might also be zero. Another
consideration is to avoid truncation error. For example, setting HNOFLO
to 99.999 should be avoided because the output might not be written with
adequate precision. Instead, it is recommended that HNOFLO and HDRY be set
to large negative integer values such as -1.0E10 and -2.0E10.
- Model Viewer reads unformatted files much more
quickly than formatted files. Therefore, for a faster animation, the head file
(and drawdown file, if saved) should be unformatted.