VULNERABILITY OF OCEANIC DUNE SYSTEMS UNDER WIND PATTERN CHANGE SCENARIOS IN URUGUAY

The dynamics of the large dune systems adjacent to lowlands and to the oceanic coastline in Uruguay is likely to be affected both by sea lev el rise and wind circulation patterns. A simple eolian sand transport model, which relates wind friction, frequency and direction to sand tr ansport, was used to estimate annual sand transport as a measure of th e impact of potential climate changes on the stability of dune systems and beaches. The model was adjusted to local conditions using real wi nd-matrix and eolian-transport data from the past 5 decades. The clima te change scenarios considered assume a positive or negative 10% chang e in the frequency of the South Atlantic Anticyclone winds, since its position determines the near-surface wind circulation pattern. Results obtained at the Cabo Polonio study area indicate that, in the medium and long term, coastal recession is likely to occur due to a decrease in coastal dunefield activity induced by changes in wind pattern. It w as also observed that, should current anthropogenic impact in the area remain unchanged, the situation would be equally serious even under a non-climate-change scenario. This is due to the fact that the foresta tion process that has taken place over the past 20 yr has caused the i mmobilization of a significant portion of the dune system, preventing natural sand transfer to the coast. In recent years a still insufficie nt deforestation effort, intended to stop coastline recession, has tak en place.