Fine sediment dynamics in the Río de la Plata

Abstract. This paper investigates the main characteristics of the fine sediments dynamics in a very complex and extensive inner shelf area located in South America, the Río de la Plata. The results derive from a 5 yr international research program that allowed intensive data acquisition throughout the area, as well as the development of the first numerical model investigating sediment dynamics at a regional scale in the area. The model is based on the MARS3D suite: it computes the regional tide- and wind-induced circulation, as well as sediment mixtures dynamics (erosion, advection and deposition of several sedimentary variables). Erosion due to wave action is taken into account thanks to the use of SWAN. The hydrodynamic and wave models were calibrated against several measurements in different zones of the Río de la Plata. Turbidity data (time series and vertical profiles) were then used in order to calibrate the sediment dynamics model. The model is shown to accurately reproduce the sediment concentration variability during both fair and stormy weather conditions in the intermediate and in the outer Río de la Plata. The paper also shows that the suspended sediment dynamics in the Río de la Plata is mainly driven by water/bottom exchanges.