some time in the past This is update 63 of 17 January 2018.

Thanks to suggestions made by Sue Guo, on 15 January 2018, the spatial agro-hydro-salnity model SahysMod was given additional facilities for annual calculations whereby the annual input files are automatically created and opened.

On 19 January the same facilities were provided to the modernized SaltMod model that already included an enlarged number of crop rotation types.

On 20 January a new page was added to illustrate the use of the amplified segmented regression model SegRegA to fit S-curves (sigmoids) to the data on crop yield and growth factors like soil salinity and depth of watertable.

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Since the first publication, in June 2002, download opportunities are given of computer programs SegReg, CumFreq, EnDrain, RainOff and Saltmod.
Download facilities of (1) a lecture note with applications of SegReg, CumFreq and RainOff and (2) an article on the energy balance of ground water (groundwater) flow belonging to EnDrain are also given.
      Since then the web site was regularly updated and extended as follows.

UPDATE RECORD (the 57 updates before 2015 have been omitted)

In update 62 of 17 August 2017crop sensitivity to shallow watertables with examples for different crops in different countries. All examples result from measurements in farmers' fields. A new piece of software was introduced by the name of NashMod. It is a computer program for the calculation of streamflow resulting from rainfall in a watershed or catchment area. Contrary to RainOff, which uses the concept of a non-linear reservoir, NashMod employs a cascade of linear reservoirs, a concept elaborated by Nash. Simultaneously, the Rainoff model was udated to improve the pasting of data copied from a spreadsheet like Excel to the table on the input tabsheet.On 25 September a new pdf text was entered dealing with the appliacation of the SaltMod model in Egypt. On 9 October the PartReg regression program to detect the longest horizontal trendline, aiming at defining tolerance levels, was given a confidence interval for the this level. On 30 November the spatial agro-hydro-salinity model SahysMod was given the facility to create polygonal maps of all output data. On 3 January 2018 the rainfall-runoff model RainOff was made more versatile by dividing the discharge range into a high and a low section.
          In update 61 on 11 April 2017 examples of crop tolerance to soil salinity measured in irrigated farm lands were added in the new tolerance page. On 21 April new pdf files were uploaded with data on salt tolerance of crops determined in farmers'fields in Egypt and Pakistan. On 26 April the CumFreq program for probability distribution fitting was adjusted to deal with zero data values, thanks to a suggestion by Ivor Growns. On 16 May the application for partial regression was given an F-test and additional graphics options. On 10 July the rainfall-runoff simulation model was given a calculator for the computation of the reaction or response factor (reservoir function) of agricultural subsurface drainage systems with pipes or ditches.
          In update 60 of 2 October 2016 the input menu of the SegReg program (for segmented regrssion analysis) and the CumFreq program (for cumulative frequency and probability distribution fitting) have been changed to facilitate more effective changes in the number of data. On 3 October the same was done with the RainOff program for rainfall-runoff modeling. On 11 November the CumFreq program was given the simple exponential distribution next to the generalized one at the request of Charles Tomkins. On 16 November the CumFreq program was updated again to include the usual normal and lognormal probability distributions omitting the optimization of mean and standard deviation. On 3 March 2017 the distribution of the evaporation over the various rootzone layers in the LeachMod program was refined leading to a small change in the salinity distribution over these layers.
          In update 59 of 6 March 2016 the source code of software and programs, which were elaborated with Borland's Delphi 7, have been made available for free download on the source code page . On 7 April 2016 the LeachMod program for soil salinity simulation has been updated and the initial soil salinity can be given for 3 rootzone layers separately instead of 1 value for the whole rootzone. On 6 July 2016 the LeachMod model was given a calibration and a verification mode. A LeachMod version for two neighboring areas is in development. There appears te be a large demand for such type of apps. On 9 July 2016, a partialized segmented regression program was introduced by the name of PartReg instead of SegReg with the purpose to detect the longest horizontal trendline aiming at defining tolerance levels more percisely.
          In update 58 of 25 May 2015 The
SaltMod model for seasonal calculations of soil salinity and watertable depth under different hydrologic and soil conditions was given an extended version for a larger number of crop rotation types. Also, a SaltMod version was developed with a modernized user interface for data input. The SahysMod model, based on SaltMod, but much larger as it is based on a polygonal network with a groundwater model, was also given a version with a larger number of crop rotation types. All new versions can be made available on request. On 11 July 2015 the LeachMod model, based on SaltMod but somewhat simplified thus enabling shorter time intervals, has been updated in the sense that a more rigorous data check was introduced.
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