Since the early years of 1970s, Research Group for Water Balance had pursued a study of the hydrogeological systems in the Kumamoto groundwater basin as a basic research for the planning and an effective water resources management. I have summarized those hydrogeological studies on Kumamoto Area and basic concepts of permissive limit or capacity of the environment is being settled among the concerned persons in the field of groundwater pollution. It is necessary for the evaluation of groundwater resources based on socio-engineering and evironmental geology in each groundwater basin to build a groundwater model.; Groundwater basin, Hydrogeology, Simulation, Management, Environmental capacity, sustained yield