SahysMod :   Spatial agro-hydro-salinity and ground-water (groundwater) model based on a system of polygons
Totally free download of software
Summary: Sahysmod is a mathematical (numerical) computer program (model) for simulation and prediction of the salinity of soil moisture, ground and drainage water, the flow of groundwater, depth of the watertable (water table) and the drain discharge in irrigated agricultural lands under different geohydrologic conditions, varying watermanagement (water management) options, including the re-use of groundwater (ground water) for irrigation by pumping from wells (conjunctive use), and several crop rotation schedules. The aquifer may be unconfined (phreatic) or semiconfined (semi confined, leaky). The spatial variation is accounted for by a nodal network of polygons.
General: Sahysmod combines the agro-hydro-salinity model SaltMod and an adjusted/extended polygonal groundwater (ground water) model SGMP of my colleague Dr.J.Boonstra. It allows for the introduction of unconfined (phreatic) and semiconfined (semi-confined, leaky) aquifers.
    The modelling (modeling) helps in determining sustainable land use and environmentally sound watermanagement (water management) for sustainability.
    When the maximum number of polygons (300) is used, the data base becomes quite large. The latest version has improved network-making functions and a version with more than 300 polygons can be made available on request.
Details: The model calculates waterbalances (water balances, budgets), actual from potential evaporation (evapotranspiration), capillary rise, deep percolation, and groundwater (ground water) flow.
    Optionally, farmers' responses can be simulated adjusting agriculture and irrigation to waterlogging (water logging) and salinity.
During May 2005, Mr. Juan Manuel Mendía and Mr. Javier Sassi, Comahue University, Rio Negro, Argentina, have made considerable efforts to test the input menu. As a result it was adjusted in many instances. I would like to express my gratitude to both gentlemen.
    In September 2006 I visited the university of Bonn (Germany) where the model is used for assessment of watermanagement (water management) in a valley in Marocco (reference). As a result the model was further improved and extended to accommodate particular situations.
    In November 2008 the guided procedure for construction of the polygonal network was improved thanks to the efforts of Mr. Tsegay Fithanegest Desta who applied the model in NE Thailand (reference) . Again, the procedure was extended as a result of comments by Mrs. Francesca Verones from Switzerland.
    On 20 September 2011 the program was given the facility to bring the rotation type under the farmers' responses, which resulted in version 1.3.3
On 24 September 2011 the general input interface, in some cases, was given a multiple choice box instead of an edit box.
    On 3 July 2012 SahysMod was totally brought under Delphi so that the auxiliary Fortran files are no longer required and the size of the package was considerably reduced. This is version 2.1.1. On 25 Novenber 2012 also the option was given to paste polygonal coordinates from the clipboard.
    Tanks to correspondence with Joel Monschke, an output writing error of soil salinity that crept in lately with a new update was restored on 21 June 2013.
Mapping: The program provides only graphs, no maps (except the polygonal network map). However, it gives the option to produce *.prn text files of input and output features which can be used in GIS, CAD, and other contour (isoline) mapping programs. A free and simple program for this purpose is QuikGrid (yes, not QuickGrid). For a guide and examples of mapping with QuikGrid see Mapping Guide or, with more detail, Case studies .
Start: The program starts clicking on Sahysmod.Exe.
More information is given in the program itself.
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See table of contents
of manual
See intro/principles
of SahysMod
See slide show
The manual contains the principles, theory, user menu and examples of application. It can be found on the articles page, from where it can be downloaded.                                                                        
The table of contents of the manual can be seen on-line.
Also, the introduction of the SahysMod manual can be viewed on line as a .PDF document.
In addition, a PowerPoint slide show can be viewed on-line or downloaded.
Download the
SahysMod program
Go to articles page
to download
the manual
Download slide show

  External links

Satem or Surdev
publication from
Contact ILRI
for software
For the determination of hydraulic aquifer properties like hydraulic conductivity used in SahysMod one may consult the pumping test publication "Software for Aquifer Test Evaluation, SATEM" by J.Boonstra and R.A.L.Kselik. For free download of the scanned publication in PDF format go to the Alterra-ILRI download page. View here the table of contents.
For irrigation efficiencies used in SahysMod one may consult the publication "Surface Irrigation Software, SURDEV" by M.Jurriëns, D.Zerihun, J.Boonstra and R.A.L.Kselik. For free download of the scanned publication in PDF format go to the Alterra-ILRI download page. View here the table of contents.
Mail to Kselik at ILRI to obtain free copy of the Satem or Surdev software.
The model calculates actual from potential evaporation (evapotranspiration), capillary rise,deep percolation, and groundwater (ground water) flow. Values of reference evapotranspiration needed in SahysMod can be found from the CropWat model and ClimWat data base that can be downloaded from the FAO website.

CropWat and ClimWat
software and
FAO website.

  Polygonal input screen of SahysMod program:                                  
here comes an image        
Example of output
here comes an image
See also: Mapping Guide.

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