some time in the past    

This is update 67 of January 2022.

The modernized SaltMod model called SaltModM was updated eliminating a few irregularities in the input menu when constructing a brand new input file.

On 15-03-2022 a new model was added called DrainApp. It has similarity to LeachMod, but it is extended to contain the determination of subsurface drainage parameters from the system properties and to enter observed drain discharges for comparison with the simulated ones.

On 12-05-2022 the amplified SegReg model called SegRegA was given a different way of presenting the confidence interval of the breakpoint in the graphs of the segmented regressions of types 2, 3 and 4.

On 30-6-2022 a new version of LeachMod called was created called LeachModS with the option to enter time dependent salinities of the irrigation water. The same facility was added to a new version of SaltModMY called SaltModMYr .

On 01-7-2022 an article titled:" How to derive a probability distribution from a data set using the simple method of plotting positions and the free CumFreq model" was entered, see plotting.

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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 shown below.
Note. Since November 2020 the download of software was no longer done through *.EXE files but through *.ZIP files. So the *.EXE references below
are not valid any more. For any problem contact me at connection.

UPDATE RECORD (the 60 updates before 2017 have been omitted)

In update 66 of June 2021SegRegA was given a power function in addition to the S-curve, quadratic and cubic regressions, generalized by a transformation of the X-data to obtain a better fit. Further the user interface on the input sheet was updated. The problem with the Gompertz distribution in the CumFreq and CumFreqA programs for probability distribution fitting when data <1 occur has been solved. Also, the Erlang (Gamma) and Rayleigh distributions were added. Two new pages on S-curve and Cubic regressions have been entered. The modernized SaltMod version SaltModM for agro-hydro-soil-salinity modeling has been given the option to perform calculations year by year for manual and annual input changes. On 22 June 2021 a new additional version has been made, called SaltModMY, with the possibility to include in the input menu the irrigation, rainfall, runoff, surface drainage and agricultural data for all years over which the model is instructed to run. It can be made available on request, but it can also be downloaded from this address. This version will definitely not require manual input changes each year On 23 July 2021 the CumFreq and CumFreqA models for probability distribution fitting were given scientific instead of standard notations for the distribution parameters. On 9 August 2021 the LeachMod model for leaching and desalination of soils was extended with options for rice cropping, surface drainage and optimization of the depth of the watertable in the software LeachModE. Download from the leachmod page. On 13 Agust 2021,the RainOff, RainOffQ and RainOffT programs (see this page) were given the posibility to input a variable instead of a constant escape (evaporation) rate.
          In update 65 of 17 March 2019,the modernized SaltMod program for the agro-hydro-soil-salinity model, called SaltModM, was extended with the possibility to vary the different climatic data from year to year by entering them in the input file. On 14 April my list of publications was updated. On 27 April the SaltCalc software was streamlined. On 8 August an article on the versatility of the generalized logistic probability distribution was added together with the use of the CumFreq program. On 29 September, the PolySalt program, a simplied version of the spatial (polygonal) hydro-agro-soil-salinity model SahysMod, but using smaller time steps, has been given the same polygonal mapping facilities as SahysMod. An article on these facilities can be found with this link
          In update 64 of 17 July 2018, An amplified SahysMod model, was developed providing mapping options of output data like soil salinity and watertable depth etc. In addition it has increased the number of crop rotation possibilities. Also, it automatically creates annual input files when the calculations are done year by year with intermediate input changes. On 21 August the amplified SegReg model, SegRegA, was given the option to apply a cubic regression based on matrices, determinants and matrix inversion. It often yields an S-curve. On 28 August the CumFreq program for probability distribution fitting was enriched with the Kumaraswamy distribution. On the same day the cubic regression page was added. On 5 December the RainOff program for the simulation of runoff from rainfall was given two sisters: RainOffT and RainOffQ. The first uses a numerical optimization method to detect the linear reservoir function, while the second does the same for a quadratic function.
          In update 63 of 15 January 2018, thanks to suggestions made by Sue Guo, 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. On 23 January a new paper on the comparison between drain and well spacings resp. for horizontal en vertical drainage was added as a spacings paper On 8 February the RainOff model for rainfall-runoff relations using a non-linear reservoir was given a conterpart, RainOffT, that uses a trial and error procedure to find the reservoir function instead of determining it from periods with zero rainfall On 17 February, thanks to a suggestion by Madhu Kandampadath, the CumFreq program for probability distribution fitting was given an extension putting the generalized extreme value (GEV) distribution on the list of options. Two days later the composite Laplace distribution was added On 22 March the Cumfreq program was given the option to view a list of probability distributions ranked according to their goodness of fit. On 25 March an additional page was added to illustrate the use of the amplified CumFreq model (CumFreqA) for the fitting of composite probability distributions to a data set On 6 April 2018, the probability density function (PDF) was included in the histogram of the CumFreq and CumFreqA programs. On 27 May 2018, thanks to observations of John Haddy, the Burr and Dagum (Burr mirrored) distributions were included. Three days later the Gompertz distribution was incorporated.
          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.
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