Measurement of Freshwater Discharge in an Estuary by Acoustic Tomography

The freshwater discharge is an important hydrological quantity on coastal planning, management, and environment conservation. In order to monitor the discharge in real time, an acoustic velocity meter (AVM) has been developed and deployed at a tidal estuary. The AVM installed at a shallow tidal river, where water depth and salinity change significantly, successfully measured the cross-sectional average velocity and discharge in a spring tide. In addition, the mean salinity was measured from the sound speed data of the AVM. The freshwater discharge was deduced from the discharge and salinity data.