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, in German). 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) . Start: The program starts clicking on Sahysmod.Exe. More information is given in the program itself.

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  Documentation

VIEW ON LINE     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.

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  External links

Download Satem or Surdev publication from Alterra-ILRI website   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.

Download CropWat and ClimWat software and manuals from FAO website.

 

 Polygonal input screen of SahysMod program:

   Example of polygonal network

Example of output