Run Hydrus-1D from the command line
Yes, it is possible. The documentation for Hydrus-3D give you the syntax (http://www.pc-progress.com/en/OnlineHelp/HYDRUS3/Hydrus.html?RunningComputationalModulesinaBa.html)
In brief here is what you need to do:


In the installation folder of Hydrus, create a text file, name it run.bat
You need to write two lines of code for every  simulation you wish to perform:


copy path1 level_01.dir      (here path1 can be replace what what ever name you want)
h2d_calc                     (this is the executable so depending on the type of model you want to run you may have to adjust the name)

In the installation folder of Hydrus create a text file and name it path1 (or whatever name you wrote in step 2), do not forget to remove the .txt extension for the case display here)
In the path1 file, write the path to your input files
for example: c:\program files\ussl\hydrus3d\mydirect\run1


Then double clicking on the bat file will trigger the model to run. By adding successive copy ... and h2d_calc commands you can chain model execution 

In addition some tricks are available here: https://www.pc-progress.com/forum/viewtopic.php?f=4&amp;t=679