Water Characteristics and Issues of Groundwater in Kumamoto City and Neighboring Municipalities

Abstract

 The region including Kumamoto City and neighboring municipalities is called “Kumamoto area”. The Kumamoto area is a quite unique urban region worldwide because the drinking water demand for over one million population in this area is covered by only groundwater. Although the water volume of the groundwater is still abundant and its water quality is also excellent, there is fear that the decreasing trend of groundwater level and the deterioration of water quality recently. The author has been working to study on the water quality conservation of the groundwater in this area for the past 15 years. In this article, water-quality characteristics of the groundwater are reviewed based on the origin and flow system of the groundwater in the Kumamoto area. In addition, the knowledge about groundwater contamination by nitrate nitrogen at current is illustrated, and finally the effect of the 2016 Kumamoto earthquake on the groundwater quality is explained.