Use of simulations to evaluate the balance between recharge and pumping to contribute to the development of policies for sustainable groundwater use in the Kumamoto area, southern Japan

Abstract

For sustainable use of groundwater, it is important to know the past and current water balance and the impact of changes in land and water use for working with stakeholder collectively. In order to understand these issues, a distributed hydrological model that includes the key processes of the regional hydrological system is considered to be a powerful tool, as it enables us to understand the impact of human activities at any given site. In the Kumamoto region, which is almost 100% dependent on groundwater for drinking water, there have been attempts to understand groundwater flow and water balance qualitatively and quantitatively. For example, groundwater levels have been monitored for about 30 years or more, mainly by the local government, to understand the current status of groundwater in the Kumamoto area. Based on these data, a multi-stakeholder group including government, academia and the private sector has developed an integrated surface-subsurface model to reproduce long-term changes in groundwater levels (Kawasaki et al., 2023). This presentation will present the results of several simulations using this model of possible future scenarios in the Kumamoto region, which identify key factors for sustainable groundwater use in the Kumamoto region.