Environmental assessment of pre-dredging sediments and proposals for their subsequent management in the port of Mar del Plata, Buenos Aires, Argentina

Nowadays, the discharge of sediments from dredging works into the sea is one of the most critical problems affecting coastal management. Therefore, the characterization, assessment and handling of the materials to be dredged is of utmost importance. Since its creation, the Port of Mar del Plata, Buenos Aires, Argentina, has presented a structural difficulty that affects its operation: the interruption of the strong littoral drift by its breakwaters generates an important sand sedimentation, blocking the access channel. This hampers the entry and maneuverability of large ships, while promoting sediment imbalances on a regional scale, causing coastal erosion on many beaches. At present, the administrative authorities of the port are proposing a new dredging work in order to restore adequate navigation depths. On this basis, the aim of this work was to assess the current sediment characteristics of the Port of Mar del Plata and compare it with previous results from 1996. Grain size, water content and organic matter were monitored at 12 stations. The results indicate that the external sector receives a larger share of sand than in 1996; silts and clays are preferentially deposited at the inner docks; organic matter, with increases compared to the previous study, accumulates in the inner docks with lower water renewal and higher contributions of waste-water. Based on these results, this work proposes beach nourishment as a management alternative for dredged sediments. Several urban beaches of Mar del Plata subject to regional-scale erosive processes could be the target sites. It is expected that this study will be used as a baseline for the improvement of the environmental quality of the port system as well as for pre- and post-dredging studies within the framework of an integrated coastal zone management.