University of FloridaDepartment of Agricultural & Biological Engineering

 

WinGAmpt

WinGAmpt is a Windows-based teaching tool for Green-Ampt Infiltration for Unsteady Rainfall Model.

GAmpt

GAmpt Fortran 77 command line documentation.

Program Description

The program follows the method of Chu (1978), Mein and Larson (1971, 1973) and Skaggs and Kaheel (1982) to calculate infiltration for unsteady rainfall using the Green-Ampt equation.

The program runs in DOS mode and is written in Fortran 77. Command line UNIX and DOS versions are available from the authors upon request.

Program Usage & Output

Unpack the contents of the ZIP package on a directory. The program (gampt.exe) and sample files will be written into this directory.

The program inputs are chosen as arguments from the command line. A short description of the program use can be obtained by executing the program with no arguments:

  • > gampt <return>

******************************************
*    Green-Ampt Unsteady Rainfall       *
*    Version 0.3, 3/02/00, jep, rmc          *
*                                                                   *
*    To run type:                                          *
*      gampt soilsfile rainfile (> outfile)   *
*                                                                   *
*    where:                                                   *
*      soilsfile = soil input data                 *
*      rainfile   = rainfall inputs                  *
*      outfile    = output filename              *
*                                                                   *
******************************************

For example, if your executable is named gampt.exe, and the input files soils.inp and rawrain.inp, then you would type (note that the soil file goes before the rainfall one):

  • > gampt soils.inp rawrain.inp

The user could edit the enclosed sample files, replace the contents with the values from the case to analyze, and change the names to new names reflecting the new application. Note also that the screen output could be redirected to a file (sample.out) as:

  • > gampt soils.inp rawrain.inp > sample.out

Input File Examples

The program input files are written in ASCII format. These are sample input files:

  • File: soil.inp
  • 0.1         0.0                               --> sol. time step (h),time offset (h) [usually 0]
    0.044    22.4    0.499    0.25   --> Ks(cm/h), Sav(cm), Sat.WC, Init.WC (cm^3/cm^3)
    0.75                                            --> maximum surface storage s(cm)
  • File: rawrain.inp
  • 0.0    1.0    1.5                           --> start hours, end hours, rainfall intensity cm/h
    1.0    2.0    0.1
    2.0    4.0    1.0

Ouput File Examples

The program output files are written in ASCII format. These are sample input files:

Working with Soils data     = soils.inp
Working with Rainfall data = rawrain.inp
-----------------------------------------------------------------
|    Green-Ampt Solution for Unsteady Rainfall    |
|    by J.E. Parsons, v0.3, R. Munoz-Carpena       |
|    Routines from Papers by Mein and Larson    |
|    1971 and Chu, 1976. See Reference Sec.     |
|    Version as of 03/02/00. jep-rmc                        |
-----------------------------------------------------------------
-----------------------------------------------------------------
|    INPUT PARAMETERS                                         |
|    Sat. K                                = .0440 cm/h              |
|    Sav                                    = 22.40 cm                  |
|    Sat. Water Content        = .499 cm^3/cm^3      |
|    Initial Water Content      = .250 cm^3/cm^3     |
|    Maximum Surface Stor. = .8 cm                        |
|    Solution Time Step        = .10 h                         |
-----------------------------------------------------------------
----------------------------------
|    Rainfall Distribution   |
|--------------------------------|
|    Start    End    RFi         |
|    Time   Time                 |
|     -----     -----     -----        |
|       h         h       cm/h      |
|--------------------------------|
|      .00    1.00    1.50       |
|    1.00    2.00      .10       |
|    2.00    4.00    1.00       |
----------------------------------

 

Green-Ampt Test Routines
Based on work of Mein & Larson and Chu
------------------------------------------------------------------------------------------------------------------------------
Time h tp h tpp h R cm/h P cm F cm fp cm/h f cm/h S cm RO cm
------------------------------------------------------------------------------------------------------------------------------
.000 .000 .000 1.50 .00 .000 .000 .000 .000 .000
.100 .112 .057 1.50 .15 .150 1.680 1.500 .000 .000
.112 .112 .057 1.50 .17 .169 1.500 1.500 .000 .000
.212 .112 .057 1.50 .32 .282 .914 .914 .037 .000
8.100 .112 .057 .00 3.60 2.230 .154 .154 .030 1.341
8.200 .112 .057 .00 3.60 2.245 .153 .153 .014 1.341
8.294 .112 .057 .00 3.60 2.259 .153 .153 .000 1.341
------------------------------------------------------------------------------------------------------------------------------
Note: npp in tp or tpp means no ponding in period.

 

Event Statistics
Cum. Infiltration (cm)    =  2.259
Runoff (cm)                     =  1.341
------------------------------       --------
Cum. Inf+ Runoff (cm)  =   3.600
Total Rainfall (cm)         =  3.600

Peak Runoff Rate (cm/h)  =  4.836    at time  =  2.900 h
Peak Rainfall Int. (cm/h)    =  1.500    at time  =    .000 h
------------------------------------------------------------------------------------------------------------------------------

References

  • Chu, ST. 1978. Infiltration during unsteady rain. Water Resources Research. 14(3):461-466.
  • Skaggs, R.W. and R. Khaheel. 1982. Chapter 4: Infiltration. Hydrologic Modeling of Small Watersheds. Ed. by C.T. Haan, H. P. Johnson and D.L. Brakensiek, 139-149, St. Joseph, MI, ASAE. pp. 121-168.
  • Mein, R.G. and C.L. Larson. 1971. Modeling the infiltration component of the rainfall-runoff process, Bulletin 43, University of Minnesota, MN, Water Resources Research Center.
  • Mein, R.G. and C.L. Larson. 1973. Modeling infiltration during a steady rain. Water Resourc. Res. 9(2):384-394.

Program License

The program was developed for teaching purposes. This program is distributed as is with no warranty. If the program is found useful the authors ask that acknowledgment is given to its use in any resulting publication and the authors notified. The source code is available from the authors upon request:

  • Rafael Muñoz-Carpena
    Professor, Hydrology & Water Quality
    Department of Agricultural
     & Biological Engineering
    University of Florida
    P.O. Box 110570
    287 Frazier Rogers Hall
    Gainesville, FL  32611-0570

    (352) 392-1864 x287
    622-1864 x287 (Suncom)
    (352) 392-4092 (fax)
    carpena@ufl.edu

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This page was last updated on May 15, 2012.