Estuarine Turbidity Maxima and Variations of Aggregate Parameters in the Cam-Nam Trieu Estuary, North Vietnam, in Early Wet Season

This study aims at exploring the characteristic parameters of the Estuarine Turbidity Maxima (ETM) and at investigating their tidal variations within the Cam-Nam Trieu estuary (North Vietnam) during the early wet season. Six longitudinal river transects were performed at spring tide. Two types of ETM were observed: an upper well mixed ETM with high Suspended Particulate Matter (SPM) concentrations up to the surface at low salinity (0.11 to <1 psu), and a lower ETM confined in a bottom layer over stratified waters at salinities between similar to 1 psu and 15 psu. Their length depended on the longitudinal salinity gradient and was highest at low tide than at high tide. D-50 of the flocs varied between 35 and 90 m, their excess of density between 60 and 300 kg m(-3) and their settling velocity ranged from 0.07 to 0.55 mm s(-1) with values between 0.12 and 0.40 mm s(-1) in the core of ETMs. The average fractal dimension of flocs was estimated to vary between 1.93 (at high tide) to 2.04 (at low tide).