Abstract
To construct and conserve a tidal flat with biodiversity, it is necessary to understand the influence of subsurface groundwater discharge on the tidal flat environment. In this study, long and short term variations of groundwater in Ota River Delta are revealed based on groundwater level and quality data measured from 2002 to 2012. Moreover, the influence of delta groundwater on groundwater quality and the effect of steel sheet pile on groundwater circulation are also discussed. It was found that various subsurface environments were formed by different groundwater conditions. Further, the groundwater conditions were strongly varied by the construction of steel sheet pile.
