FINE SEDIMENTS TRANSFERS THROUGH THE RIO DE LA PLATA : AN INVESTIGATION BASED ON NUMERICAL MODELLING AND IN SITU MEASUREMENTS

TESSIER, C.; SIMIONATO, C. G.; DRAGANI, W. C.; CAVALOTTO, J. L.; MARTELLA, G.; MENENDEZ, A.; PIEDRA CUEVA, I.; GUERRERO, R. A.; NUÑEZ, M. N.; CAYOCCA, F.

Bahía Blanca, Argentina

Congreso; ECSA 44; 2008

Estuarine and Coastal Science Association

The overall FREPLATA project (GEF-PNUD) aims at studying the environmental processes in the Río de la Plata; within this project, a specific FFEM-funded contribution (French environment Fund) began in 2008 to investigate fine sediment transfers through the Río. The environmental motivation of this contribution lies in the relationship between fine sediments dynamics and water quality as well as primary production, but although navigation channels dredging. The project gathers several partners from French, Argentinean and Uruguayan institutes (IFREMER, SHN, SOHMA, INIDEP, INA, IMFIA, CIMA).The study is based on 1) the development of a hydrodynamic and sediment transport numerical model (MARS-3D) of the Río de la Plata; 2) the acquisition of in situ data during one year (long time series provided by 3 fixed monitoring stations and investigation of the spatial and seasonal variability through measurements along 2 transects over 6 cruises); 3) satellite image processing in order to obtain a synoptic view of the surface concentration of both inorganic particles and chlorophyll a ; 4) the development of an Integrated Information System.  MARS-3D software (Lazure and Dumas, 2008) is implemented in the Río de la Plata on an oriented grid of 3 km-resolution extending to Los Patos Lagoon in order to track the full river plume’s extension to the North. It is forced by a 10 km-resolution broader model which computes the astronomic and atmospheric tides (taking into account wind spatial variability from WRF atmospheric model) over the whole continental shelf. River inputs (Río Paraná and Río Uruguay) supply water and particles to the model and waves are taken into account from SWAN simulations over the same area. The sediment transport model considers a semi-realistic sediment cover described by the mixture of 3 particles types: clay, silt and fine sand, according to the observations (figure 1). Theses particles are able to be resuspended by waves and currents and then transported by currents in the water column.