Impacto ambiental do asfaltamento da BR101 sobre as marismas de São José do Norte (RS, Brasil): Estado atual efeitos potenciais

• Autor(a) principal: Costa, César Serra Bonifácio
• Data de Publicação: 2000
• Outros Autores: Marangoni, Juliano César
• Tipo de documento: Artigo de conferência
• Idioma: por
• Título da fonte: Repositório Institucional da FURG (RI FURG)
• Texto Completo: http://repositorio.furg.br/handle/1/3125

The Federal Government's decision to cover the southern part of the BR 101 highway between the towns of Tavares and São José do Norte with asphalt, called for a study to evaluate the induced effects on land-use and development not just along the highway but also on 2.11 km² (211 hectares) of salt marshes of the Patos Lagoon estuary, located in a possible transportation corridor of this enterprise. The study combined a method of visual impact quantification and an impact matrix analysis for both, actual and postenterprise scenarios. Five salt marshes units, with surface areas ranging from 0.09 to 1.27 km², can be differentiated by their spatial continuity and/or dominant plant cover. In each salt marsh seven structural and six functional impacts were discriminated over two to three 10,000 m² plots. Eighteen herbaceous plant species were found. Owing to the origin of sediments, São José do Norte marshes range from recently formed sandy marshes near the estuary inlet to older inner marshes with lagoonal sediment rich in silt-clay and organic matter. The most frequent and intense structural impacts today are cattle and horses grazing, embankments and excavation of drainage canals. The main functional impacts are garbage deposition and eutrophication from sewage. The analysis of post-enterprise scenario without environmental safeguards found that the seriousness of impacts on salt marshes should increase 1.6 to 4.5 times (up to 70% of the maximum impact 2 seriousness value). Additionally, burning and prune of vegetation, previously not characterized as important functional impacts, could become major environmental problems. Using the scenario of implementation of environmental safeguards, such as placement of educational and regulation signs, patrol to prevent fires, grazing, oil spill, stream channelization, domestic and industrial pollution, it was demonstrated that the impact seriousness level can be maintained and even reduced in some marshes.