PhD Defence - Soutenance de thèse
PhD Defence - Truong An NGUYEN
Modeling of nutrient dynamics in an urbanized tropical estuary and application to eutrophication risk management
3 PM Monday, 20th December, 2021
UNIVERSITÉ GRENOBLE ALPES
presents
PhD Defence - Soutenance de thèse
Modeling of nutrient dynamics in an urbanized tropical estuary and application to eutrophication risk management
Presenter: Truong An NGUYEN
3 PM Monday, 20th December, 2021
Zoom link
https://univ-grenoble-alpes-fr.zoom.us/j/98244508698?pwd=WG1FemEzQURkdFJJcGRCbDhQMVBGQT09
Meeting ID: 982 4450 8698
Passcode: 760834
Urbanized tropical estuaries in emerging countries are experiencing an imbalance between urbanization and water quality management practices. The lack of monitoring and modeling programs has not allowed understanding the dynamics of nutrients. This thesis aims to study nutrient dynamics in a tropical estuary under the influence of a megacity. Three specific objectives are (i) assessing the biogeochemical functioning of an urbanized tropical estuary (Saigon River Estuary, Vietnam) receiving wastewaters of Ho Chi Minh Megacity (HCMC); (ii) quantifying the role of controlling factors (e.g., nutrient loads, reaction rates, hydrological conditions) in the eutrophication development; (iii) assessing eutrophication risk under the scenarios of rapid urbanization and increased wastewater treatment capacity.
The Carbon-Generic Estuarine Model (C-GEM), a one-dimensional, reaction-transport model, was applied after calibration with the limited datasets existing in developing countries. The biogeochemical functioning was evaluated by analyzing monitoring data (physiochemical, phytoplankton structure and abundance, and greenhouse gases) and completed by the modeling approach. The C-GEM was calibrated and validated for Saigon River Estuary at steady-state in the dry season to evaluate the intensity of biogeochemical reactions. Dynamics of nutrients, phytoplankton, eutrophication were assessed by the transient version of C-GEM for 2017-2018. Statistical methods (e.g., Principal component analysis, Redundancy analysis and Hierarchical Partitioning) were applied to evaluate the contribution of environmental parameters to the responses of phytoplankton, eutrophication, greenhouse gases emissions. Finally, scenarios oriented towards megacity development were evaluated using C-GEM to assess the eutrophication risk.
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