the input data year by year. The program also offers the possibility to follow historic records with annually changing input values (e.g. rainfall, irrigation, agricultural practices), the calculations must be made year by year. If this possibility is chosen, the program creates transfer files by which the final conditions of the previous year (e.g. water table and salinity) are automatically used as the initial conditions for the subsequent period. This facility makes it possible to use various generated rainfall sequences drawn randomly from a known rainfall probability distribution and obtain a stochastic prediction of the resulting output parameters. If the computations are made with annual changes, not all input parameters can be changed, notably the thickness of the soil reservoirs and their total porosities as these would cause illogical shifts in the water and salt balances. Output data The output of Saltmod is given for each season of any year during any number of years, as specified with the input data. The output data comprise hydrological and salinity aspects. The data are filed in the form of tables that can be inspected directly or further analyzed with spreadsheet programs. As the soil salinity is very variable from place to place (figure left) SaltMod includes frequency distributions in the output. The figure was made with the CumFreq program . The program offers the possibility to develop a multitude of relations between varied input data, resulting outputs and time. However, as it is not possible to foresee all different uses that may be made, the program offers only a limited number of standard graphics. The program is designed to make use of spreadsheet programs for the detailed output analysis, in which the relations between various input and output variables can be established according to the scenario developed by the user. Although the computations need many iterations, all the end results can be checked by hand using the equations presented in the manual. See also Spragg Bags References External links The model can be freely downloaded from : . The manual is freely available from : or directly as pdf file : . Soil chemistry Soil physics Environmental chemistry Environmental soil science Agricultural soil science Hydrology models Irrigation Drainage Land management Land reclamation Scientific simulation software