Long term variation of unconfined and confined groundwater level and quality in Ota River estuary

Abstract

Groundwater circulation is one of important substance transportation process in delta area. It is affected by the variation of groundwater level and quality. To understand variation factors of unconfined and confined groundwater level and quality in Ota River Delta, the long term data were analyzed since 1975 to 2012. The confined groundwater level is varied with sea water level and upper river water level. Moreover, the sea water level in Hiroshima bay increases 20 cm compared with 1975 and the confined groundwater level increases 130 cm compared with 1975. The unconfined groundwater is varied with precipitation.