Development of a methodology for the characterisation of the long-term geosphere evolution. (2) Estimation of the long-term evolution of groundwater flow conditions in a Tono area case study

A methodology for estimation of the long-term evolution of groundwater flow conditions is being developed using approaches based on deductive and inductive methods, in a case study of the Tono area, Central Japan. Based on studies using the deductive approach, it has been confirmed that the combination of physical modelling of topographic change and groundwater flow simulations is available for estimating changes in groundwater flow conditions in the future due to topographic and climatic perturbations. Existing information needed for estimation of surface hydrological conditions, and which are to be used for assignment of boundary conditions for the groundwater flow simulation, has been gathered from many sources and reviewed based on modern-analogue methods. In the studies using the inductive approach, palaeo-hydrogeological studies have been carried out on several spatial and time scales. Through studies at the largest spatial scale, a methodology needed to understand changes in groundwater flow conditions due to long-term topographic change is proposed that can effectively identify the optimum area for site characterization investigations in the field. Information to estimate the palaeo-topography and palaeo-climate has been obtained from literature surveys and field investigations. Through these studies, it has been confirmed that these two approaches are available for estimation of the long-term evolution of deep groundwater flow conditions. (author)