The image below comes from a poster presentation created by a GMS user, Andrea Borgia, who has been using GMS for pre- and post-processing of TOUGH2 models. Although GMS doesn't have an interface to the TOUGH2 model, Andrea has developed a workflow to make it work. In GMS 10.1 it will be possible to export UGrids to TOUGH2 MESH input files. Thanks Andrea!

GMS TOUGH2 poster