HydroGeoSphere/Specified Head

This is also known as a first-type, Dirichlet, or constant head boundary condition. It is a nodal property so you should first define the subset of nodes for which you want to apply the condition and write them to a nodal data set.

The following instructions can be used as input to the Type instruction inside the Boundary condition...End instruction group to assign various specified head boundary conditions:

Head
Sets the input type to be a general specified head boundary condition.
 * &bull; &bull; &bull;

For example:

would define a specified head of 100.0 from time zero for the duration of the simulation for all of the nodes contained in the node set inflow.

These heads can be interpolated or turned on and off as discussed in Section 5.7.

Head equals elevation
Sets the input type to be a special form of the specified head boundary condition where head is set equal to the elevation of the node. This is normally the z-coordinate, unless the instruction y vertical has been issued, in which case the y-coordinate is used instead.
 * &bull; &bull; &bull;

For example:

This example shows that a time-value table is not required, since heads are derived from the nodal elevation. However, if you wish to turn the boundary condition on or off, then this can be accomplished by including a time value table instruction:

The value 1.0 at time zero is ignored, but the NODATA value -99999 at time 10.0 causes the boundary condition to be turned off and the nodes become unconstrained.

Head equals initial
Sets the input type to be a special form of the specified head boundary condition where head is set equal to the initial head at the node.
 * &bull; &bull; &bull;

For example:

This condition can be turned on and off as discussed above for Head equals elevation.