Data Evaluation of the Seabed-Mount Type ADCP in Ago Bay for Future Installation of Online System

Abstract

Through the analysis of observed data obtained by the Ago Bay Project, it has been recognized the relation between the intrusion of seawater from outer sea and the movement of the oxygen depleted water mass pooled in the bay head, where the large amount of cultivation of pearl oysters is performed. Forecasting the movement of the oxygen depleted water mass is very beneficial for the industry, and possible, if the intrusion of sea water is detected rather before its arrival to the bay head. Based on this idea, the current velocity data recorded by the ADCP (Acoustic Doppler Current Profiler) set-up on the seabed at the center of Ago Bay was investigated. The analysis shows the high correlation between the volume-flux just above the ADCP and the total volume-flux through the transverse cross-section of the central bay. It also shows that the increment of salinity in the bottom layer at the central bay follows the increment of the eastward volume-flux of the bottom layer. The eastward flux corresponds that towards the bay head. These facts suggest the availability of the use of ADCP data for the detection of intrusion. The present ADCP system is offline and the data is retrieved once two months. The establishment of the online system is required for realization of forecasting.