Estimation of Freshwater Inflow in a Tidal River

The in-and outflow of water and salt in tidal estuary was estimated by means of the box model modified to adapt to a shallow tidal estuary. The tidal variations of salinity profile were estimated using the tidal variation of depth of the sensors. The tidal variations of the estuary' s volume and longitudinal salinity distribution were also considered in the model. The water inflow from upstream inlet estimated by the box model was verified with the inflow through the up stream water gate. The groundwater discharge may affect on the budget of the water and the geochemical constituent in the Ota River estuary.