Pilot points > Implementation

programs

When pilot points were first introduced, they were supported by members of the PEST groundwater utility suite. Functionality provided by most of these programs is now provided in more flexible ways by PLPROC. However some of these older utilities are still supported by some graphical user interfaces. Furthermore, they may be useful in certain situations. So they are worth mentioning.

The following table lists programs of the groundwater utility suite which support pilot points parameterisation in one way or another. A brief description of what each one of them does is also provided. Those of the following programs that undertake spatial interpolation employ ordinary or simple kriging (it's your choice).

Program	Task
PPK2FAC, PPK2FAC1, PPK2FAC2	Calculate a set of kriging factors for 2D interpolation from pilot points to a structured MODFLOW grid. They also record information that can be used by other programs to add preferred-difference regularisation to a PEST control file.
PPK2FAC3	Similar to other PPK2FAC* programs, but adjusts kriging factors to avoid interpolation across tributaries of an alluvial system.
FAC2REAL	Reads kriging factors calculated by the above programs, and then uses these factors to interpolate hydraulic property values from pilot points to the nodes of a structured MODFLOW grid.
PPKREG, PPKREG1	Add prior information equations that encompass preferred-value or preferred-difference regularisation to a PEST control file based on information recorded by PPK2FAC* utility programs.
PPK2FAC3D	Calculates kriging factors for 3D interpolation to a structured grid model.
FAC2REAL3D	Reads kriging factors calculated by PPK2FAC3D, and then uses these factors to interpolate hydraulic property values from pilot points to the nodes of a structured MODFLOW grid.
PPK2FACG	Calculates a set of kriging factors for 2D interpolation from pilot points to a general grid.
FAC2G	Uses kriging factors calculated by PPK2FACG to undertake 2D interpolation from pilot points to a general grid.
GENREG	Adds prior information equations to a PEST control file that embody simple or complex regularisation relationships applied to families of pilot point parameters.
VERTREG	Adds prior information equations to a PEST control file that implement "vertical regularisation" where parameterisation is based on pilot points. Regularisation can be based on ratios or differences of pilot point parameter values.
PARM3D	Extends the functionality of pilot points to two-and-a-half dimensions. Assignment of hydraulic properties to individual layers of a multi-layer MODFLOW model can first be implemented using pilot points. Hydraulic properties can then be assigned to intervening layers through vertical elevation-based or layer-based interpolation.
PPSAMP	Undertakes least squares sampling of a MODFLOW-compatible real array of arbitrary hydraulic property complexity. Sampling points are pilot points. If interpolation from these pilot points to the model grid is then undertaken, it provides the best fit in the least squares sense to the original hydraulic property field.
TWOARRAY	Adds, subtracts, multiplies or divides two MODFLOW-compatible real arrays.

ppk2fac_alluv

PPK2FAC3 allows continuity of interpolation without crossing from one tributary to another.