Monitoring discharge in a tidal river using water level observations: Application to the Saigon River, Vietnam

Abstract

The hydrological dynamics of the Saigon River is ruled by a complex combination of factors, which need to be disentangled to prevent and limit risks of flooding and salt intrusion. In particular, the Saigon water discharge is highly influenced by tidal cycles with a relatively low net discharge. This study proposes a low-cost technique to estimate river discharge at high frequency (every 10 minutes in this study). It is based on a stage-fall-discharge (SFD) rating curve adapted from the general Manning Strickler law, and calibrated thanks to two ADCP campaigns. Two pressure sensors were placed at different locations of the river in September 2016: one at the centre of Ho Chi Minh City and one in Phu Cuong, 40 km upstream approximately. The instantaneous water discharge data were used to evaluate the net residual discharge and to highlight seasonal and inter-annual trends. Both water

Phytoplankton characterization in a tropical tidal river impacted by a megacity: the case of the Saigon River (Southern Vietnam)

“…4). In contrast to the rainy season, the residual water discharge in Saigon River was very low (30 m 3 s − 1 ) during the dry season (Camenen et al 2021). The residence time of the water body in this urban section of Saigon River was estimated to be around two months (Nguyen et al 2021).…”

“…The ow direction of the Saigon River is predominantly driven by the asymmetric semi-diurnal tides that lead to the ow current inversion twice a day, roughly in the range from − 1500 to + 1500 m 3 s − 1 (Camenen et al 2021). The region falls within a tropical monsoon climate with two distinct seasons.…”

Biogeochemical functioning of an urbanized tropical estuary: Implementing the generic C-GEM (reactive transport) model

“…The high polluted loads regularly lead to an excess of nutrients and intense periods of anoxia, especially during the dry season . There have been several studies in recent years showing the risk of eutrophication in this estuary, especially in the dry season because of low flushing capacity (Camenen et al, 2020;Strady et al, 2017). In addition, the research results of showed that there was no significant difference between water quality variables in rainy season and dry season (except chlorophyll a).…”

“…Hydrological data (water level, velocity, discharge) were measured monthly at 10 stations along the Saigon and Dongnai rivers by the CEM. Once a month, the hydrological monitoring stations track the evolution of water level and velocity over 24 h (2 tidal cycles) to calculate the net water discharge by removing the influence of tidal fluctuations in the Saigon River Estuary (Camenen et al, 2020).…”

“…The simulation of water quality for conditions representative of an average dry season is therefore a reasonable choice for our study. During the dry season, the upstream flow discharge is low and quite steady (Camenen et al, 2020;Nguyen et al, 2020a). In contrast, a lack of high resolution data for precipitation, runoff and river discharge during the rainy season would have resulted in reliability issues of the modelling, especially in developing countries such as in Southeast Asia with a low monitoring effort (Guiamel and Lee, 2020).…”