Environmental sensitivity of the coastal islands of Ubatuba, SP, Brazil

Abstract

The Environmental Sensitivity Index Maps for Oil Spills (ESI Maps, or SAO in Portuguese) constitute an essential component and source of basic information for emergency planning, response decision support and damage evaluation in case of oil spills. This study aims at the elaboration of sensitivity maps for oil spills for the islands within the Ubatuba municipality, north coast of the State of São Paulo. The adopted methodology is based on the Technical Specifications for the production of Environmental Sensitivity Maps for oil spills (SAO maps) proposed by the Brazilian Ministry of Environment. The study involved the gathering of secondary data, followed by field work carried out in the summer and winter periods of 2007; the elaboration of the cartographic base maps and, finally, the integration of the data to a GIS (Geographic Information System). As a result it was registered and mapped the physical (geology, geomorphology, oceanography and climatology), biological (fauna, flora and coastal environments) and socioeconomic (anthropic influence, human use, artificial structures and impacts) resources of Ubatuba coastal islands. Eleven beaches have been identified, located at six islands, with distinct topographic and geomorphologic features. The beaches were classified with sensitivity index 4, because they are sheltered from actions of waves and currents. Most of the mapped environments (44.8%) were classified with sensitivity index 8, indicating high sensitivity of the islands. The oil spill impacts on coastal environments can be significantly minimized during the contingency actions when previous knowledge of the ecosystems that compose the islands environment is available, especially when it is integrated into GIS data basis, capable of displaying easy-to-use maps. The environmental sensitivity mapping is an important management instrument, especially when dealing with sensible and poorly studied areas such as the islands of Ubatuba.