Spring discharge mechanism along the southeast coast of Yonaguni Island in the southern Ryukyu forearc

Abstract

Study region: Spring along the southeast coast of Yonaguni Island, located at the western end of the Ryukyu forearc. Study focus: The chemical composition of groundwater, including SF6 concentration, was investigated to clarify the mechanism of groundwater discharge around Sanninudai on the southeast coast of Yonaguni Island. New hydrological insights for the region: Accurate determination of groundwater flow paths is essential to the conservation and management of groundwater sources and their sustainable use. Other areas around the world may show similar complexity, requiring a review of past findings. This possibility indicates the need for re-examination of groundwater sources around the world. In particular, the development of novel analytical methods for chemical components may provide valuable information. The chemical composition of spring water on remote islands, where anthropogenic activities have little influence, should be investigated continuously to monitor the effects of sea-level rise caused by global warming.

Keywords

• Yonaguni Island
• Spring water
• Discharging mechanism
• Seawater influence
• Apparent residence time