Project description WEO3 :
VIETNAMINS : "VIETNAMese INtegrated Study of particle production, transport and fate
along the coast of the Red River delta and in the Haiphong estuary associating field data,
remote sensing and modeling".
At the interface between continental areas and oceans, estuaries and coastal zones
are locations of energy exchange through currents, waves and tide, and matter exchange
(water, organic and inorganic particles, dissolved pollutants). These environmental
interfaces strongly impact socio-economic activities. In particular, their hydro-sedimentary
functioning determines the navigation ability, the siltation of harbours (like Haiphong
harbour), the transport of pollutants and contamination, and the morphodynamics (beach
erosion, coastline changes), as well as the productivity of coastal zones. The overall
objective of the project is to set up an integrated study of particle formation, transport
and fate including field data, laboratory experiments, remote sensing and numerical
modelling, with application to the Northern part of Vietnam (Halong Bay, Red River
Delta and Haiphong Bay). Concerning remote sensing, Vietnam will launch in next April
or May the satellite VNRedSat-1, which will offer many opportunities for ocean color
applications, like in particle transport. Modelling will include the delivery of an integrated
tide/wave/current/sediment model and will focus on modelling the physico-biological
mechanisms of aggregation/disaggregation of sediments, based on profiles of turbulence
in the water column, on availability of Suspended Particulate Matter (SPM), and
abundance and stickiness of Transparent Exopolymer Particles (TEP) -which act as
“biological glue” in the aggregation process- with varying salinity, turbulence and Black
carbon concentrations (Lefebvre et al 2012, Mari et al 2012). This model will take into
account the stratification of the water column and its influence on the above mentioned
parameters. It will be implemented in a numerical model at local scale (Delft3D or
MARS3D) reproducing the hydrodynamics of the estuary, forced at its boundaries by a
regional numerical model (ROMS). Furthermore, USTH supports from 2010 a PhD on
tidal modeling in the Gulf of Tonkin, for application to sediment transport. This project
aims at developing an integrated study of particle formation, transport and fate in the
Northern part of Vietnam (Halong Bay, Red River Delta and Haiphong Bay) through the
association of USTH (N.N. Minh and upcoming PhD students), STI which is a main
support of ocean color and satellite studies in Vietnam, IMER which has developed from
a long time sediment modeling studies in these areas, which has long partnership
experience with the French partners from IRD teams and which is the main partner of
USTH in oceanography, and French partners from the consortium.
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This project follows a preliminary joint study EC2CO-HAIPHONG (2008-2010, IRDVAST) which had identified various elements of the hydro-sedimentary estuary of the
Cam River. It is also a complement to on-going joint projects VITEL and GlobCoast (see
above). Remote sensing data being widely used in oceanography, this project will build
relationships between the Department “Space and Applications” and the WEO
Department of USTH. It is also complementary to several ongoing projects developed by
IMER and IRD which aim at describing the effect of Black carbon deposition on
aggregation/disaggregation and sedimentation processes (IMPALA, CARPEDYEM,
SOOT, COME&SEA and BLACKISH, see above). In this framework, a M2 WEO
internship of USTH (Do Thi Phuong Thao) is currently being conducted with IMER,
under the co-supervision of two IRD units (LEGOS and ECOSYM): Biological and physical
aggregation/disaggregation process in mixing jar.
The project will benefit from the arrival in Hanoi in 2013 of one of the first Vietnamese
doctors trained within the USTH PhD program in France (Nguyen Nguyet Minh). She
adapted and validated a numerical model of tide in the Gulf of Tonkin from tide
measurements and satellite altimetry. A new PhD from the upcoming doctoral school of
USTH will begin within this project fall 2013. The main partners will be USTH, IMER
and STI (VAST, Hanoi), IRD, UPS, ULCO and IFREMER (France). Its duration is 4
years.
The detailed research project can be divided in five complementary tasks:
WP1 - Collection, processing, and analysis of already available high spatial resolution
satellite data, such as SPOT and Landsat. The Landsat images are available for the studied
area since 1982. Based on these data, appropriate algorithms will have to be developed to
estimate the sediment concentration of water surface. Validation exercises will have to be
performed from field measurements based on simultaneous field measurements and
satellite overpass. Maps of sediment concentration will then be generated for different
environmental conditions and analyzed using sediment transport modeling. A preliminary
task should have to be performed on the selection of the satellite images in relation with
the spatial and temporal resolution of the model used.
WP2 - Particle formation and transport processes: advanced analysis of the main
unknown processes in particle transport in the study area. Focus on particle aggregation
in a gradient of salinity, turbulence, Black carbon and organic matter so as to improve its
formulation in a multi-class sediment transport model. This WP will be developed both
during field and laboratory/experimental approaches. The experimental approach will be
conducted in IMER’s facilities.
WP3 - Set-up of an all-integrated tide-wave-current-sediment model and its application to
the Red River Delta and Haiphong Bay.
WP4 - Preparation and realization of a pilot study for the VNRedSat-1 satellite: at sea and
in river measurements during satellite overpass, then modeling and comparing simulations
and satellite data, to better integrate both in coastal monitoring. The VNRedSat-1 satellite
will image at 2.5 m in panchromatic mode and 10 m in multi-spectral mode (four bands)
with a 17.5km swath, and will orbit at 680 km in a sun synchronous orbit. It should be
launched in April 2013 from French Guyana. STI is in charge of the control of the
satellite as well as of the processing.
WP5 - Calibration/validation of the integrated model (WP3) from available satellite data
(WP1), from enhanced knowledge of processes and new formulas (WP2), and from
physical measurements (currents & turbulence depth-profiles) and optical measurements
(absorption, scattering, turbidity, which can infer SPM abundance, size index and nature)
(WP4).