Analysis of Sedimentation Problems at the Entrance to Mar del Plata Harbor

Mar del Plata Harbor is an important center for the fishery industry in Argentina, and it has become an attractive site for international tourism because of the recent construction of a cruiser ship terminal. However, further development of this port halted several years ago because of the recurrent sedimentation problems in the access channel and basins. This site is characterized by advancement of the shoreline south of the harbor and a sandbank that develops across the access channel, while downdrift erosion and the associated shoreline retreat are due to partial blockage of the sediment transport caused by the harbor breakwaters. The mechanisms responsible for these sedimentation and erosion processes are examined using a coastal area morphological modeling system, MIKE 21/3 Coupled Model Flexible Mesh, developed by DHI. The morphological model was calibrated and validated against measured bathymetric changes. The model was then applied to a medium-term simulation with particular interest in the assessment of the effectiveness of reestablishing the design depth of the access channel through dredging. This morphological modeling allowed enhanced understanding of the main hydrodynamic and sedimentological processes occurring around the harbor entrance, as well as obtainment of information potentially useful for maintenance dredging. It was determined for the present hydrosedimentological conditions that the sandbank moves toward the access channel with high sedimentation rate. This means the navigation channel requires regular maintenance dredging or the construction of additional sediment retention interventions such as sediment traps, extension of the breakwater(s), etc. The efficiency of any intervention from the point of view of reducing sediment deposition at the harbor access should be verified before its implementation. In all cases, the northward transport would still be blocked, so artificial sediment bypass should be considered to protect the beaches north of the harbor.