University of FloridaDepartment of Agricultural & Biological Engineering



SWINGO (Shallow Water table INfiltration alGOrithm) is a Fortran command line program to calculate infiltration for soils bounded by a shallow water table.

Program Description

SWINGO simulates infiltration in soils under realistic initially non-ponded conditions with a shallow water table and steady rainfall conditions. The program consists of a time-explicit infiltration solution based on a combination of approaches by Salvucci and Entekhabi (1995) and Chu (1997) with the assumption of a horizontal wetting front. It includes new integral formulae for calculation of the singular times (time of ponding, shift time and time to soil profile saturation). This stand-alone version of SWINGO was developed to study the effects of a shallow water table on infiltration (Muñoz-Carpena et al., 2017). The program is now coupled with VFSMOD to study the effects of a seasonal shallow water table on the effectiveness of vegetative filter strips for water quality mitigation (Lauvernet and Muñoz-Carpena, 2017).

Program Usage & Output

Unpack the contents of the ZIP package on a directory. The source code (swingo.f and quad.f) and sample files will be written into this directory. You can then compile the fortran file for your system type. For example for Intel Fotran Composer in unix (ifort),

> ifort -o swingo swingo_v1.f quad.f <return>

Part of 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:

  • > swingo <return>

    Name: swingo
    (Calculate soil infiltration under shallow water table conditions
    using Salvucci/Chu algorithm)
    Usage: swingo WTD rain (setim)
    Options: WTD: water table depth (m)
    rain: rainfall intensity (m/s), if 0 initial ponding
    setim: if present, time (s) to print solution
    Version: 1.0 for Unix -Jun. 2017
    Authors: R.Munoz-Carpena & Claire Lauvernet (UFL & IRSTEA)

The water table depth (m) and rainfall rate (m/s) for each run are read from the command line, where the soil characteristics are provided in the soil input file swingo.iso. (see details in Iinput File Examples section below).. For example, to obtain the cumulative and instantaneous infiltration rate, and wetting front rate time series for a sample clay soil with a shallow water depth (1.5 m) and a rainfall intensity of i=0.73 cm/h (2.4e-6 m/s),

  • > swingo 1.5 2.04e-6 <return>
  • Water table depth at (m): 1.500
    Rainfall intensity (m/s)= 2.040000000000000E-006
    Time to ponding, tp(s,h)= 8518.47334380493 2.36624259550137
    Shift time, to(s,h)= 4202.11307340253 1.16725363150070
    Depth to water table saturation (m)= 0.599990999909999
    Time to reach WT, tw(s,h)= 18098.9882335323 5.02749673153676
    Cum. infiltration at tw(m,cm)= 3.048812924941849E-002 3.04881292494185
    time(h) F(cm) f(cm/h) z(cm)
    0.0251 0.0185 0.7344 0.2040
    0.0503 0.0369 0.7344 0.4086
    0.0754 0.0554 0.7344 0.6136
    0.1005 0.0738 0.7344 0.8191
    0.1257 0.0923 0.7344 1.0252

Input File Examples

a) Structure of the file

The program input file (swingo.iso) is written in ASCII format and are compatible with VFSMOD, with the following structure:






b) Parameter Definition
VKS                saturated hydraulic conductivity, Ks (m/s)

SAV                 Green-Ampt’s average suction at wet front(m) (neededin file but not used)

OS                  saturated soil-water content, i (m3/m3)

OI                    initial soil-water content, s (m3/m3)

SM                  maximum surface storage (m)

SCHK             relative distance from de upper filter edge where the check for ponding conditions is made (i.e. 1= end filter, 0.5= mid point, 0= beginning)

WTD                water table depth (m)

ITHETATYPE  an integer to select the soil water characteristic curve type with values: 1= van Genuchten, 2= Brooks and Corey

PAR(I)             parameters of the soil water retention curve for van Genuchten (VG) and Brooks and Corey (BC): OR/OR VGALPHA/BCALPHA VGN/BCLAMBDA VGM/(VHb if ITHETATYPE=2).

IKUNSTYPE  an integer to select the unsaturated hydraulic conductivity curve type with values: 1= van Genuchten, 2= Brooks and Corey and 3=Gardner’s

PARK(J)        parameters of the unsaturated hydraulic conductivity van Genuchten (VG), Brooks and Corey (BC) and 3=Gardner (GND): VGM/BCETA/GDNALPHA BCALPHA (VHb if ITHETATYPE=2)

ITWBC, RVH end time boundary condition- 1(or number missing): Dupuis-Forchheimer, lateral drainage to a stream, f=VKS.FWIDTH.WTD/VL.avgSlope; 2: Vachaud vertical saturated flow to a deeper horizon, f=VKS. RVH: VKS/LateralKs so LateralKs=VKS/RVH) (if not present default RVH=1)

c) Example file

3.4e-007 1.1694 0.45 .05 0 1 --> Ks(m/s) Sav(m) Theta-s Theta-i Sm(m) Schk
1.5                   --> Water table depth (m)
2                     --> Vachaud vertical boundary condition

Ouput Files

The program outputs resutls directly to the screen. If desired they can be written to a file by writing,

  • > swingo 1.5 2.04e-6 > clay.out <return>


  • Salvucci GD, Entekhabi D.: Ponded infiltration into soils bounded by a water table. Water Resour. Res., 31, 2751-2759, doi:10.1029/95WR01954, 1995.

  • Chu ST.: Infiltration model for soil profiles with a water table. Trans. ASAE., 40(4), 1041-1046, 1997.

  • Muñoz-Carpena, R., C. Lauvernet, N. Carluer. Shallow water table effects on water, sediment and pesticide transport in vegetative filter strips: Part A. Unsteady rainfall infiltration and soil water redistribution. Hydrol. Earth Syst. Sci. Discuss. in review, July 2017.

  • C. Lauvernet and R. Muñoz-Carpena. Shallow water table effects on water, sediment and pesticide transport in vegetative filter strips: Part B. model coupling, application, factor importance and uncertainty. Hydrol. Earth Syst. Sci. Discuss. in review, July 2017.

Program License

The program was developed for research and 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 at the link above.

The model and associated documentation is supplied as-is with no warranty - explicit or implied. The model is provided to you as an educational and research tool under the terms of the Open Source Initiative, Educational Community License, Version 2.0 

  • 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
    (352) 392-4092 (fax)

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This page was last updated on July 08, 2017.