13 UNSWIFT POSTPROCESSING

The UNSWIFT program written by GeoTrans converts map files (UNIT 13) to regularly-spaced grid for SURFER using bilinear interpolation in order to create contour plots. SURFER is a registered trademark of Golden Software, Inc.

The UNSWIFT program is written in FORTRAN 77 and is currently operational on a 80386 and 80486 using the FTN77/486 compiler from the University of Salford. The program can read pressure, temperature, brine or nuclide concentration data from a SWIFT map, and prepare a grid file compatible with SURFER7.

As an alternative approach, files can be viewed directly in Groundwater Vistas.  Use Plot>Import SWIFT Results..

13.1 OVERVIEW

SWIFT-2002 produces results for block-centered, variably-spaced finite difference grids. Plotting software such as SURFER7 however, work with uniformly-spaced, node-centered grids in order to contour given data. Therefore, without UNSWIFT, results from SWIFT would have to be read as "randomly-distributed" data for contouring.

Gridding randomly-distributed data is time-consuming and may introduce error. While the distribution pattern of the data points is regular and known, it cannot used by SURFER7. UNSWIFT converts this "regular" data from the model to the contouring package using bilinear interpolation. Note that it is not guaranteed to work in all situations. Sometimes, head or concentration results from a model require a more sophisticated interpolation approach.

Thus, UNSWIFT provides a convenient and accurate means to prepare contour plots by preserving the lattice nature of the map data. This is done expediently and without the introduction of erroneous contours.

An example of a SWIFT grid for a layer is shown below.

Values are calculated at block centers. The grid increments are nonuniform.

UNSWIFT converts array data from the above grid to the one shown below.

Note the changes in coordinate system and the node-centered data on the resulting grid.

The outer boundary of the resulting grid should be within the original grid, as UNSWIFT does not extrapolate beyond one grid cell. A bilinear interpolation technique is used to convert the data.

13.2 OPERATION

The operation of UNSWIFT is illustrated below.
 
 
SWIFT
  
 
â 
  
 
stair.map
 Variable-grid file
 
â 
  
unswift.ctl à 
UNSWIFT
  
 
â 
  
 
prs_ly2.grd
 Uniform grid file
 
â 
  
 
SURFER
  
 

STAIR.MAP is an unformatted map file generated by SWIFT. The map writing option is invoked by setting MAP > 0 in R2-13. UNSWIFT.CTL is a control file for UNSWIFT which contains information necessary for the conversion of SWIFT data. PRS_LY2.GRD is the uniform grid file generated by UNSWIFT which is ready for contouring. The uniform grid file can be in formatted or binary form.

For a typical problem with SWIFT, the control file will remain the same. The map file STAIR.MAP will change with each run. The map file may contain data for many stress periods, time steps, and layers. UNSWIFT lets one look at each array interactively and process only those needed for gridding.

13.3 INPUT DATA GUIDE FOR THE CONTROL FILE

Each record in the input data file is preceded by a record header line containing the names of variables for that record. The variable names are placed in the header line aligned with the columns where the input data is expected for the variable. For illustration, header line and sample data are shown below for Record 2.

NX NY ICODE IDEBUG FMTGRD Record 2
19  51     0          1       (8G10.0)

NOTE: DO NOT DELETE THE HEADER LINES IN THE CONTROL FILE! The following records are to be used to create the UNSWIFT control file.

RECORD 1: TITLE RECORD (A60, A10)

Title record is only for documenting the control file. It is ignored by UNSWIFT.
 

  RECORD 2: INPUT GRID SIZE, FORMAT OPTIONS (4I10, A20)
  11-20: NY: Number of rows dimensioned in SWIFT. Maximum allowed is 250.

21-30: ICODE:

0= Variable to uniform translation (SWIFT to SURFER). [Common Usage]
1= Uniform to variable translation (SURFER to SWIFT).
  31-40: IDEBUG: 0=No action
1=Create extra output to check control file input.
  41-60: FMTGRD: Format for the DELR, DELC grid spacing given in Records 8 and 9. Example: (8E10.0). If the List-Directed option is used to input R1-17, 18 or 19, then a * can be used for FMTGRD and portions of the SWIFT input file can be used directly.   RECORD 3: VARIABLY-SPACED GRID PARAMETERS (I10, A30, I10, 2G10.0)
  0 = binary

1 = formatted (as per FMTH, see cols 11-40 of this record).
 

 11-40: FMTH: Format of the variably-spaced file. Example:'(8E12.3)'. If IFMTH=0, leave blank.

41-50: ILOG: Log (base 10) transformation of variably-spaced data.

0 = no transformation.

1 = yes, perform transformation.

The log transformation is appropriate for concentration plots with data ranging in many orders.
 

 51-60: HCUT: Lower cut-off or truncation value for variably-spaced data. In the same units as head or concentration. 0 = No, do not create a grid file

1 = Yes, do create a grid. The program will prompt for the file name. Usually this option is only necessary for the first execution of UNSWIFT. For production runs, set IGRID=0.
 

 RECORD 4: UNIFORMLY-SPACED GRID PARAMETERS (I10, A30)
  0 = binary (only SURFER)

1 = formatted (as per FMTZ, see cols. 21-40 of this record).
 

 11-40: FMTZ: Format for the uniformly-gridded file. Example: (8E10.3).
  If IFMTZ=0, leave blank. RECORD 5: WINDOW OPTION (4I10)

Specify all the parameters. Enter a blank or a zero for IL, IR, IT, IB if window option is not used.
 

Note: To invert the grid from top-left origin to bottom-left origin, enter a negative value for IB.
 
 

RECORD 6: UNIFORM GRID DESIGN (2I10, 4E10.0)
 

  For example, the total x-distance of a model is 5000 ft, and the total y-distance is 4000 ft.

DELX is equal to 5000/(NXX-1), and likewise

DELY is equal to 4000/(NYY-1).
 
 

RECORD 7: NO-FLOW AND DRY CELL CODING (2E10.0)

SWIFT-2002 has special values meaning no-flow and dry cells.
 

RECORD 8: MODEL GRID SPACING in X-DIRECTION (see FMTGRD on RECORD 1)

Provide the array DELC(NX) in the format specified in RECORD 2 parameter FMTGRD. For large grids, one may just want to transfer the grid spacing from the model input data. The parameter FMTGRD provides a flexible way of reading this data. For an areal x-y system, the DELC() corresponds to the x-grid spacing DELX() on Record R1-17 for SWIFT. Similarly the DELR() below corresponds the DELY() on Record R1-18. For Y-Z, the DELC() would correspond to DELY() and DELR() on Record 9 would correspond to DELZ().

 

RECORD 9: MODEL GRID SPACING in Y-DIRECTION (see FMTGRD on RECORD 1)

Similar to Record 8, provide the array DELR(NY).

13.4 RUNNING UNSWIFT

The code UNSWIFT is available for the Digital Visual Fortran. Listed below are the steps to translate a variable-spaced grid (SWIFT) to a uniformly-spaced grid (SURFER7).

1. Prepare data input such that SWIFT produces map files at the appropriate times. This would include setting MAP > 0 and KMP13 = 0. The SWIFT problem should then be run. The results will be placed in a .MAP file. Note that SWIFT can produce maps for as many time steps as are necessary. Also one can create different maps from previously created restart files.

2. Prepare a control file for UNSWIFT. Start with a copy of the supplied sample control file. Copy this sample file to one's control file by typing

 COPY SAMPLE.CTL yourfile.CTL 3. Modify the control file as per the input data instruction in this manual. Using the convention illustrated in this manual and the input data guide, prepare the control data file for UNSWIFT.
  3.1 Specify ICODE=0 for translating from SWIFT to SURFER.

3.2 Determine whether the window option will be used. Determine the size of the input window in distance units.

3.3 Utilize the grid spacing in the SWIFT input data file (R1-16 - 18) for Records 8 and 9 in the control file. Make sure that the record headers are still present. The input for SWIFT is list-directed.

3.4 Maximum X and Y distance is obtained by summing the grid input for SWIFT (Records 8 & 9 in UNSWIFT.) Use these numbers (if the window option is not specified) to design NXX and DELX. Similar steps should be followed for NYY and DELY.

3.5 IFMTH can be 0 or 1, as SWIFT 2.54 prepares only either formatted or binary map files. If a grid file from SWIFT output has been prepared, set IFMTH = 1, and supply a format string under FTMH.

3.6 IFMTZ should be left as zero, as it is the most efficient way of sending data to SURFER7. If it is necessary to inspect and edit certain array data, set IFMTZ=1 and supply a format such as (8G12.5) under FTMZ in Record 4.

3.7 If one is overlaying the contour line with a BLN file in SURFER, check the coordinate of the bottom-left corner of the BLN data. If it is non-zero, supply the (x,y) offset coordinates under X0 and Y0 in Record 6.

3.8 HNOFLO, HDRY, and HCUT have their origins from earlier versions of UNSWIFT for other finite-difference codes. Generally HNOFLO and HDRY are not used. Be careful with HCUT, especially if the pressure at datum extend into the negative range. Also avoid negative logs by setting HCUT to a small positive number when ILOG=1 (Record 3).
 

 4. When running UNSWIFT (INTERACTIVELY), the user will be prompted for the control file name and the map file name. Upon successful reading of the control file, UNSWIFT proceeds to read the first header of the SWIFT map file. The example below shows typical inquiry by UNSWIFT: F:\ RUN77 UNSWIFT

<< UNSWIFT - Version 1.4 >>

Control file name: UNSWIFT.CTL

Variable grid input file: STAIR.MAP

Time Step: 50 Time: 52.00 Data: HEAD

To process, enter uniform grid file name,

[Enter] to skip, or type END to stop: PRS_LY2.GRD

UNSWIFT reads the header record for each array in STAIR.MAP and displays it on the screen. The next prompt has three possible responses: (1) If you want to process the array, enter the name of the uniform grid file to be created, (2) if you want skip this array press [Enter] key, (3) if you want to terminate further reading of the map file and ignore this array, type END.

Time Step: 50 Time: 52.00 Data: CONC

To process, enter uniform grid file name,

[Enter] to skip, or type END to stop: CON_LY2.GRD

5. RUNNING UNSWIFT IN BATCH: The version 1.3 of UNSWIFT accepts command line arguments which is convenient in running UNSWIFT through batch files. The example shown in step 4 may be run in batch by typing the following command: RUN77 UNSWIFT /PARAMS UNSWIFT.CTL STAIR.MAP PRS_LY2.GRD CON_LY2 END The file names must be separated by a space character. The last parameter should be END to terminate processing the remaining arrays in the map file.

6. Execute SURFER7 using the uniformly-spaced file created in the previous step as the input grid (eg. CON_LY2.GRD) file for contouring.

  

13.5 SOME COMMENTS ON CODE IMPLEMENTATION

1. This version must be compiled with the same compiler as that used for SWIFT. Many FTN77-specific statement are used in UNSWIFT. This version is written specifically for operating on 386/486 computers.

2. By default all non-ASCII files are "unformatted". A clever method is utilized in UNSWIFT by writing "unformatted direct access" file to appear like a "binary" file readable by SURFER7.

3. If problems arise in reading the binary map with UNSWIFT or reading the binary grid in SURFER7, change to ASCII format and examine the respective file contents for potential problems.

4. Note that the output file from UNSWIFT can be written in ASCII. This allows input into programs other than SURFER7, but note that the data have already been interpolated. Recontouring the data could produce misleading results depending on the method used. This is not true with SURFER7 because the grid input file has been written in exactly the same format that SURFER7 can read directly without recontouring. If one uses a different contouring package, the results should be checked against SURFER7 output as this is the only package supported for use with UNSWIFT.

5. It is recommended that the window option be turned OFF initially so that the entire output may be checked.

6. List-directed input is recommended for use with UNSWIFT. This allows the grid dimensions to be imported directly from the SWIFT input file. This eliminates unnecessary input errors. To instruct UNSWIFT to use list-directed input, place an asterisk (*) in the first column of the FMTGRD input (Record 2, column 41).

7. Some confusion may arise over the design of the uniformly spaced grid. In order to determine the grid spacing, decide the number of grid blocks and divide the total axis distance by this number. Please note that the number of columns and rows (NXX and NYY) should be one more than the actual number of rows and columns. This is because the numbers that are being used are the number of grid lines not blocks. Please also note that the number of grid blocks in either direction should be sufficient to provide adequate resolution of your results.

8. While UNSWIFT can be used to map a relatively coarse SWIFT map onto a more refined SURFER7 grid, use caution when interpreting the contours. For example, one can use the bilinear interpolation to UNSWIFT a 20 x 30 SWIFT map onto a 101 x 151 SURFER7 grid. This will result in "smooth" contours, but may not properly reflect the trace model results. In general, the number of increments in the variable and uniform grid should be similar.

9. Great care should be taken in constructing the control file as an incorrect entry will produce misleading results.

10. The user should verify the times at which maps are produced by SWIFT. Make sure that the input data for SWIFT (R2-12, TCHG) specifies the correct time period for mapping. Producing a map at the incorrect elapsed simulation time will cause serious problems when interpreting the output data.

 

Table 13-1. Example Control File Listing.

 

 Problem title File Name                        card 1
SWIFT-2002 Sample test problem UNSWIFT.CTL

NX NY ICODE IDEBUG FMTGRD                      card 2
39 29   0      1   (8E10.0)

IFMTH FMTH     ILOG HCUT IGRID                 card 3
1    (8E12.3)    0    0     1

IFMTZ FMTZ                                     card 4
1     (8E10.3)

IL IR IT IB                                    card 5
1  39 1  29

NXX NYY DELX  DELY   X0  Y0                    card 6
51  31  219.0 240.0 0.0 0.0

HNFLO HDRY                                     card 7
0.0   0.0

DX(1) DX(2) DX(3) ... DX(i), i=1,NX            card 8
600. 600. 600. 600. 300. 300. 300. 300.
300. 300. 300. 300. 150. 150. 150. 150.
150. 150. 150. 150. 150. 150. 150. 150.
150. 150. 150. 150. 150. 300. 300. 300.
300. 300. 300. 300. 300. 600. 600.

DY(1) DY(2) DY(3) ... DY(i), i=1,NY            card 9
600. 600. 400. 400. 200. 200. 200. 200.
200. 200. 200. 200. 200. 200. 200. 200.
200. 150. 150. 150. 150. 150. 150. 150.
150. 200. 300. 400. 500.