Abstract
With poor laver harvest in 2000, the environmental problem in the Ariake Sea became social issue in Japan. Though the environmental impact assessment of the operation of water gates of this reservoir was conducted suspended solids (SS) were not included in the environmental impact assessment. Therefore, necessary information especially settlement and coagulation-flocculation related with the seawater inflow from the Ariake Sea is inadequate for the prediction of SS in the reservoir. The aims of this research are to analyze the behavior of SS under the salinity at same level of seawater and to predict the accumulation of sediment in the reservoir according to the inflow of seawater. The prediction of SS is done using parameters of settlement and resuspension obtained from model calibration during the trial opening of water gates in 2002. It is found that SS in the reservoir will become lower according to dilution by the inflow from the Ariake Sea and coagulation-flocculation under high level of salinity. Sensitivity analysis indicates that sediment will accumulate in the reservoir after the inflow of seawater.
