This report contains the conceptual lay-out for two possible expansions of the port of Bahía Blanca. To determine the best conceptual lay-outs, emphasis is drawn to understand the physical system to determine the effect of the expansion of the port on the natural system. The port of Bahía Blanca is situated at the end of a ria, or tidal basin. For the designs, different conceptual lay-outs are developed and simulated in a hydrodynamic model called MOHID. This is a 2D depth-averaged model (2DH), which uses a rough bathymetry grid of the ria to determine the effect of the port development. There are three mutations of the different port expansions on the environment, which are investigated using the MOHID-model: (1) the East expansion, containing reclamation of tidal flats and closure of a side channel; (2) the South expansion, containing a widening and elongation of the channel and reclamation of tidal flats; and (3) the deepening of the entire navigation channel to various minimum depths. From the results of the MOHID-model on the East expansion conclusions on the mutations of the different port expansions are drawn. For the East expansion, only small changes are predicted; only local erosion in the navigation channel near the expansion may occur. For the South expansion, the flow velocities reduce in the entire stretch and there seems to be sedimentation at the eastern part of the expansion. As a conclusion the best and most feasible designs are chosen. The best design is the lay-out that obtained the highest score in the MultiCriteria- Analysis (MCA). The most feasible design is the design having the highest cost/benefit ratio determined by a Cost-Benefit Analysis (CBA). The east bank is located close to the current port, Ingeniero White, on tidal flats which are inundated at high-water and dry at low-water. For the East expansion, different port lay-outs are developed mainly differing in amount of reclaimed land, length of viaducts and the presence of a mooring basin. The best design on the east is characterised as being very compact and having small viaducts between the dry bulk and agribulk terminals and jetties. The main advantage of this design is the small expected increase of siltation, good safety and sufficient future expansion possibilities. The most feasible design, however, is characterised by long viaducts reducing the costs of the design. The other appointed location for the port expansion is the south bank, opposite of the current port development. This location, however, is characterised by one main disadvantage; It is far from any form of connection with the hinterland. Nevertheless, in 2013, the port authority (CGPBB) initiated the start of small reclamation works. The best and most feasible design fully utilises this reclaimed portion of land. Moreover, the best design has a small expected increase of siltation in the port area. For a final designs, all previous designs are combined to create a design in which all the advantages of each of the designs are fully incorporated. Therefore, this design has little reclamation as well as viaducts with only intermediate lengths.