(Proceedings of Symposium HS1001 at IUGG2007, Perugia, July 2007 – IAHS Publication 312, 2007, pp. 86)
Comprehensive studies of the groundwater-seawater interface and submarine groundwater discharge (SGD) have been made at Yatsushiro, Kumamoto, Japan, and other areas, by use of automated seepage meters with conductivity sensors to evaluate SGD and fresh/saline components of SGD continuously, and Resistivity measurements to evaluate the relationship between temporal changes in the location of the saltwater-freshwater interface and SGD composition. The processes of SGD differ between the landward and offshore sides of the saltwater-freshwater interface. SGD in the nearshore can be mainly explained by connections of terrestrial groundwater, while offshore SGD is controlled mostly by oceanic process such as recirculated saline groundwater discharge. Global evaluations of SGD based solely on observational data (>25,000 automated flux measurements) showed that fresh groundwater discharge is estimated to be 2600 km3/year (from the coast to 200 m offshore) and is equivalent to 7% of the global river flux.
Submarine groundwater discharge, Terrestrial groundwater, Recirculated saline water, Saltwater-freshwater interface, Global assessment of groundwater discharge
