MASS FLUX ESTIMATION AND MASS-TRANSPORT MECHANISM IN ESTUARIES

Hydrodynamic surveys were conducted in a partially stratified estuary. Longitudinal salt fluxes through a cross-section were measured and the optimal number of lateral and vertical points for observation and estimation of fluxes of pollutants found. The hydrodynamic data were decomposed to investigate the mechanism of instantaneous and tidally averaged mass fluxes. The decomposition method developed showed that instantaneous salt flux arose principally from the combination of velocity fluctuation with the tidal mean salinity. The error analysis showed that the estimate of mass flux was sensitive to the error inherent in the velocity data and the error range was within +/- 10% of the total flux. Seven depth and four width points gave acceptable estimates of the water flux, salt flux, and longitudinal dispersion.