Yes Robert Kringel, PMWIN (processing Modflow for Windows) or AHGW (arc Hydro Groundwater analyst) its tool open source for arcGIS, but I need any tool for QGIS, can you help me?
As far as I know no open-source (QGIS) plug-in related to this exists right now.
But the good news are that a colleague (Christian Boehnke) is working on a hydraulic QGIS plug-in for his MSC thesis. Maybe you can contact him to find out more.
I've look your link, the tool seems to surface water modelling, I would learn this tool, whether they could modeling e.g. simulate groundwater flow after pumping or contaminant transport at groundwater.
This is a great step in the field of hydrogeology. Someday I'll ask you about it. I greatly appreciate, for me "R" is something new although it is already introduced by our supervisor, a hydrologist. Now I begin to learn the R.