Boundary conditions can be turned on and off by assigning special NODATA values instead of normal input in the time-value, time-raster and time-file tables. For example, the default NODATA value is -99999., and the following table:
boundary condition type head ... etc time value table 0.0 100.0 1000.0 -99999. 2000.0 100.0 end end ! new specified head
would apply the specified head of 100 from time 0.0 to time 1000.0 and then allow the node to revert to an unconstrained condition until time 2000.0, when a specified head of 100.0 would again be applied for the duration of the simulation.
For rasters and files, the default NODATA value is the string 'none'.
If for some reason you need to change the default NODATA value you can use:
- nodata_value The value that indicates there is no data.
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The following instructions are used to change the NODATA values used for rasters and files :
- nodata raster
- nodata file