Abstract
In the present study, the variations of the salinity and water discharge in the main branches of the Ota Estuary were investigated using the Fluvial Acoustic Tomography System (FATS). The Ota Estuary has a branched section of the Gion and Oshiba. The response of the salinity variations at the branches can be described as a power-law of river discharge. The exponents -0.53 and -3.86 at the Gion and Oshiba implied significant differences in the salt intrusion variations in these branches. The mechanisms of the salt intrusion at the site study were analyzed using the salt decomposition method based on the FATS data. The results indicated that the advection is the dominated seaward mechanisms at the both branches. However, the variations in the landward directed mechanisms were influenced by the triple correlation between the salinity, water velocity and water level fluctuations.
