This paper summarizes hydraulic studies carried out as part of the feasibility study for a new bridge over the Parana River in Argentina. The bridge will physically connect the provinces of Santa Fe and Corrientes, currently separated over the length a 200-km river reach. In addition to the hydraulic studies summarized here, the feasibility study includes analyses of the geology and geomorphology of the sites, land surveying, geophysical and hydrologic studies, studies of the navigation channel and fluvial transportation, transportation studies, and environmental impact studies. The main components of the present study were a geomorphologic analysis of the middle reach of the Parana River, and a quantitative hydraulic study. Qualitative and quantitative analyses provided a description of the hydraulic system, and served as a basis for a comparison of alternative bridge locations and the analysis of their vulnerability. The quantitative hydraulic study included the construction, calibration, and operation of one-dimensional (1D) and depth-averaged two-dimensional (2D) flow models. In order to tie the models to the most reliable data the 1D models covered a 450-km long reach, and included the main channel (about 2 km wide) and the flood plain (about 30 km wide). The results of the 1D models played a major role in the selection of the bridge location, and were subsequently used as boundary conditions for 2D modeling. The 2D models were constructed for a 70 km x 30 km modeling domain. This paper presents results of 1D modeling for large floods, both in the natural state and with the proposed bridge, and results of 2D modeling in the natural state. Modeling at this scale requires sound judgment to strike a balance between the desirable level of model detail and the cost of acquiring data for model construction and calibration. This paper summarizes hydraulic studies carried out as part of the feasibility study for a new bridge over the Parana River in Argentina. The bridge will physically connect the provinces of Santa Fe and Corrientes, currently separated over the length a 200-km river reach. In addition to the hydraulic studies summarized here, the feasibility study includes analyzes of the geology and geomorphology of the sites, land surveying, geophysical and hydrologic studies, studies of the navigation channel and fluvial transportation, transportation studies, and environmental impact studies. The main components of the present study were a geomorphologic analysis of the middle reach of the Parana River, and a quantitative hydraulic study. Qualitative and quantitative analyzes providing a description of the hydraulic system, and served as a basis for a comparison of alternative bridge locations and the analysis of the vulnerability. The quantitative hydraulic study included the construction, cali bration, and operation of one-dimensional (1D) and depth-averaged two-dimensional (2D) flow models. In order to tie the models to the most reliable data the 1D models covered a 450-km long reach, and included the main The results of the 1D models played a major role in the selection of the bridge location, and were used as boundary conditions for 2D modeling. The 2D models (about 30 km wide) were constructed for a 70 km x 30 km modeling domain. This paper presents results of 1D modeling for large floods, both in the natural state and with the proposed bridge, and results of 2D modeling in the natural state. judgment to strike a balance between the desirable level of model detail and the cost of acquiring data for model construction and calibration.