Generation of new littoral ecosystems by levee filling in the coast of the city of Buenos Aires

Abstract

Buenos Aires, the most largest and populated city of Argentina is emplaced on the southeast coast of the Rio de la Plata shared waters estuary. The present coastline is the result of several anthropogenic works that have induced the coastal progradation by artificial filling since 1836, developing new coastal ecosystems. The main objective of the Buenos Aires coastal planning has always been to gain land to the estuary waters as an expansive policy. It was estimated an artificial nourishment of about 12,67 hectares per year during the last 162 years with a coastal progradation between 400 to 1,000 m. This paper focuses on a new planing and management of the coast, considering the configuration of the filling levee and the generation of new ecosystems associated with different levee designs. The coastal evolution associated with four types of man-made levee was analysed during the last 40 years. The types of levees configuration described were bay, cape, spit and barrier design. The bay type induced the accumulation of coastal plains in the middle of the bay. The cape type induced lakes and ponds isolated from the estuary hydrodynamics that trend to be filled by vegetation. The barrier and spit types provoked the coastal plain progradation and the formation of an artificial lagoon dominated by tides with freshwater marshes and tidal flat ecosystems. The artificial coastal progradation of the estuary generated these new ecosystems associated as that should be predicted considering the definitive configuration of the artificial levee. This new ecosystem should be carefully assessed managed and considered by government agencies in the planification of the future coastline configuration of the city. This work should provide to decision makers of the city with appropriate conclusions, recommendations and proposals in order to give an outline for immediate, medium and long term action in the framework of a coastal management plan. It also remarks the importance of taking into account in the planning process the relation between the artificial design of the coastline and the natural systems processes.