Estuarine Turbidity Maxima and Variations of Aggregate Parameters in the Cam-Nam Trieu Estuary, North Vietnam, in Early Wet Season
Institute of Marine Environment and Resources, VAST, 246 Danang Street, Haiphong City 180000, Vietnam
UMR LEGOS, Université de Toulouse, IRD, CNES, CNRS, UPS, 14 avenue Edouard Belin, 31400 Toulouse, France
Department Water-Environment-Oceanography, University of Science and Technology of Hanoi, 18 Hoang Quoc Viet, Hanoi 100000, Vietnam
Hanoi-VNU University of Science, Vietnam National University, 334 Nguyen Trai, Hanoi 100000, Vietnam
Author to whom correspondence should be addressed.
Water 2018, 10(1), 68; https://doi.org/10.3390/w10010068
Received: 28 November 2017 / Revised: 4 January 2018 / Accepted: 11 January 2018 / Published: 13 January 2018
(This article belongs to the Special Issue Recent Progress in Research on River Deltas)
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 ~1 psu and 15 psu. Their length depended on the longitudinal salinity gradient and was highest at low tide than at high tide. D50 of the flocs varied between 35 and 90 μm, 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).