Parameter optimization of a 3D coastal model using Green's functions for modelling river plume dynamics

摘要

River plumes flowing into channels with strong tidal currents cause pulsed decreases in the salinity around the river mouth. This study constructs a numerical model for reproducing the river plumes of Asahi and Yoshii Rivers flowing into Bisan Seto, a tidal channel in the Seto Inland Sea. Recently inverse estimation of the model parameters using Green's functions has been applied to numerical modelling of sea shelves as a simple and effective method of parameter optimization. This paper examines the method that aims to improve the precision of the model results, but uses a model domain (ca. 50 km) that is much smaller than in previous studies. The reproducibility of the tidal elevations and currents was improved significantly by the parameter optimization procedures. The reproducibility of the temporal changes in salinity was also improved, although they showed strong nonlinearity. These results indicate that the inverse estimation of model parameters using Green's functions can greatly improve the reproducibility of the modelling of river plumes flowing into tidal channels.