Modeling the Rio de la Plata Circulation

A two-dimensional (2-D) depth-integrated finite element numerical model was applied to study the circulation in the Rio de la Plata estuary in the vicinity of the Port of Montevideo. In this paper, the application of the model and its calibration is presented. The hydrodynamic regime in the area of interest comes from the response of the entire estuary to different and interacting driving forces. These circumstances conduce to the need for a numerical model of the hydrodynamic regime of the whole Rio de la Plata and adjacent continental shelf. The Rio de la Plata is located on the east coast of South America, between 34° and 36° South Latitude and 54° 50 minutes and 58° 30 minutes West Longitude, between Uruguay and Argentina. It flows from the northwest towards the southeast for approximately 280 km. Its surface area is about 35,000 km², its depth varies from 3 to 20 m and its width increases from about 2 km to approximately 220 km at its mouth. The two major tributaries are the Parana and Uruguay Rivers, with annual average discharges of 16,000 m³/s and 6,000 m³/s, respectively. The model open boundary condition was hourly distributions of water surface elevations obtained from two coastal stations. The finite element model was calibrated in two stages. First, bottom roughness and astronomical forcing were calibrated with astronomical tide components obtained from tide observation at seven stations along both coasts. Even though wind effects were found not to be the primary forcing for surges, the wind drag coefficient was calibrated with comparisons of surge water levels observed at Montevideo, and then verified with surge water levels measured at Torre Oyarvide. Comparisons of calibrated model output with observational data for the Rio de la Plata have shown that the model is capable of simulating water surface elevation and current speed and direction with a relatively high degree of accuracy.