WEBVTT

00:00:00.000 --> 00:00:05.000
The letters "USGS" and the words "Science for a Changing World" appear in green then fade to black.

00:00:05.000 --> 00:00:10.533
If you are familiar with MODFLOW, you may be wondering about the IBOUND array.

00:00:10.533 --> 00:00:15.933
In MODFLOW, the IBOUND array tells whether a cell is active or inactive 

00:00:15.933 --> 00:00:19.433
or whether it is a specified-head cell.

00:00:19.433 --> 00:00:22.866
If IBOUND is positive, the cell is active.

00:00:22.866 --> 00:00:26.332
If IBOUND is zero, the cell is inactive.

00:00:26.333 --> 00:00:30.466
If IBOUND is negative, the cell is a specified-head cell 

00:00:30.466 --> 00:00:34.499
and the specified head at that cell is the initial head.

00:00:34.500 --> 00:00:41.033
In ModelMuse, the “Active” data set indicates whether a cell is active or inactive 

00:00:41.033 --> 00:00:48.033
but there is no way in ModelMuse to specify a negative value of the IBOUND array.

00:00:48.033 --> 00:00:51.699
That’s because the Time-Variant Specified Head package 

00:00:51.700 --> 00:00:59.733
is a better way to set up a specified head boundaries.

00:00:59.733 --> 00:01:06.099
The Time-Variant Specified Head package allows you to use parameters to specify heads.

00:01:06.100 --> 00:01:12.133
That makes it easier to calibrate your model with automated calibration methods.

00:01:12.133 --> 00:01:13.999
The Time-Variant Specified Head package 

00:01:14.000 --> 00:01:17.733
also allows the specified heads to vary with time.

00:01:17.733 --> 00:01:21.999
If you are used to using the IBOUND array to set up specified heads, 

00:01:22.000 --> 00:01:26.466
try using the Time-Variant Specified Head package instead.

00:01:26.466 --> 00:01:32.799
To find out more about the IBOUND array and other details of the MODFLOW input files, 

00:01:32.800 --> 00:01:38.933
check the Online Guide to MODFLOW that is part of the ModelMuse Help.

00:01:38.933 --> 00:01:48.333
You can see that by selecting “Help|MODFLOW Reference”.

00:01:48.333 --> 00:01:53.299
The letters "USGS" and the words "Science for a Changing World" appear in green.