PARNAM – is the name of a parameter to be defined. This name can consist of up to 10 characters and is not case sensitive. All parameter names must be unique.

PARTYP – is the parameter type to be defined. For the LVDA capability, the only allowed parameter type is:

•LVDA - defines the angle between the grid axis and the principal direction of horizontal hydraulic conductivity. Angle is positive in a clockwise direction with the positive x direction being zero. The angle can vary between –90 and 90 degrees. Hydraulic conductivity along the principal axis (Kmax of figure 2) is defined in the HUF Package input file by an HK parameter; the hydraulic conductivity along the minor axis (Kmin of figure 2) axis is defined by a HANI parameter in conjunction with the HK parameter. Using the LVDA capability, HANI values need to be less than or equal to 1.

Parval—is the parameter value. This parameter value may be overridden by a value in the PVAL file, the Sensitivity Process (SEN) input file, or by a value generated by the Parameter-Estimation (PES) Process.

NCLU – is the number of clusters required to define the parameter. Each Item-3 record is a cluster (variables Layer, Mltarr, Zonarr, and IZ).

Layer – is the layer to which the direction applies.

Mltarr – is the name of the multiplier array to be used to define array values that are associated with a parameter. The name “NONE” means that there is no multiplier array, and the array values will be set equal to Parval.

Zonarr – is the name of thezone array to be used to define array elements that are associated with a parameter. The name “ALL” means that there is no zone array and that all elements in the layer are part of the parameter.

IZ – is up to 10 zone numbers (separated by spaces) that define the array elements that are associated with a parameter. The first zero or non-numeric value terminates the list. These values are not used if Zonarr is specified as “ALL”.