some time in the past This is update 61 of 11 April 2017.

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.

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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 53 updates before 2013 have been omitted)

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 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.
          In update 57 of 7 August 2014 new software was added to the suite of computer programs. It concerns PolySalt a condensed version of SahysMod permiting monthly calculations of soil salinity and groundwater level in a polygonal network with a ground water model with monthly input changes instead of annual. It can be seen as the SaltCalc model applied to each polygon separately but hydrologically connected in the underground. On 24 August 2014 the guided network construction in the Sahysmod and PolySalt models was improved. On 11 September a new version of SaltCalc was made with an updated user interface for both input and output data handling. On 13 September the CumFreq program for cumulative frequency analysis and probability distribution fitting was given an additional feature: the twice generalized logistic probability distribution.
          In update 56 of 22 November 2013, the calculation of the standard error and confidence interval of the breakpoint (BP), as well as of the Y value at BP, in segmented regression using the SegReg program was standardized for the different types of segmented regression. A description of the mathematics involved, with examples, can be seen in this confidence paper. These changes were motivated by comments of Dawn Noren and Wenhuai Li. On 27 November the SahysMod spatial agro-hydro-salinity-groundwater model was given a small tolerance factor for not exactly fitting polygons in the nodal network.In January 2014 the conditions for Type 2, 3, 4 and 5 in SegReg were made more strict thanks to an example provided by John Shukman. On 4 February 2104 the titels of the data to be entered in the input tabsheet of the WellDrain program have been improved thanks to the feed back of Malcolm Woodruff. On April 28 2104 the Saltmod page was given a link to a listing of SaltMod case studies described in literature with on-line representations.
          In update 55 of 3 July 2013,thanks to suggestions made by Peter Wilson, the SegReg program was given an extended facility to deal with data pasted from a worksheet like Excel, especially in the case of varying decimal separators like dots and comma's. In addition the different regional and language settings and options in Windows are better accounted for. At the same time, all other programs using copy/paste options like CumFreq, RainOff, SahysMod, and LeachMod were updated in a similar fashion. On 20 August 2013 a new calculator was introduced for Student's t-test, concerning the comparison of averages of data series, using the t- probability dstribution. At the same time the normal distribution and F-test calculators were de-bugged.
          In update 54 of 21 April 2013 new software was introduced: LeachMod. It is designed to simulate the results of leaching experiments for the desalization of salty agricultural land under irrigation. The time step can be of a duration determined by the user (from 1 day to 1 month). The input per time step is introduced in tables so that the program performs the calculations for all the time steps in one go. When values of measured soil salinity are given, LeachMod will automatically find the optimal vaue of the leaching efficiency. On 27 April 2013, the calculator for the standard normal probability distribution was extended to include all normal probability distributions. On 21 June 2013 the SahysMod model was given additional explanation on mapping procedures with an example of the Garmsar case. Also, an output writing error for soil salinity that had crept in lately has been restored, thanks to correspondence with Joel Monschke.
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