EvoluÃÃo da linha de costa a mÃdio e curto prazo associada ao grau de desenvolvimento urbano e aos aspectos geoambientais na planÃcie costeira de Maceià - Alagoas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The position of the coastline of the municipality of MaceiÃ, Alagoas state, north east Brazil, has been affected in the last decade by both natural factors associated to the coastal dynamics and by human factors. This study analyzes the evolution of the coastline in relation to urban development and the environmental question over the medium and short term, based on analysis of historical documents, aerial photos dating back to 1955, satellite imagery, traverse topographical profiles from the beach in eight different points of the coast, and laboratory sediment analysis. Data gives evidence that urban development begins to intensify in areas along the studied coastline in the 1980âs. The local coastal plain has gone through continuos and progressive modifications due to the building of embankments in humid areas, destruction of part of the local reef, real estate activities, destruction of dune fields, interventions in the mouth of rivers, channel rectification and engeneering works. The coastline was devided into three sections on the basis of its morphological and sedimentary characteristics. Examination of the coastline variations in the medium term showed that section 1 presents relative stability and accumulation. In section 2, PajuÃara beach presents erosive tendency due to the destruction of par of the reef in the past, coulped with sediment retention in the Ponta Verde promontory and engeneering works on the backshore. In section 3, JatiÃca beach presents erosive tendency while the beaches of Cruz das Almas and Jacarecica present an accumulation tendency. The study of the coastline variations in the short term gives evidence that section 1 has a tendency to the accumulation, while section 2 is the most vulnerable one presenting erosion in the profiles P3 and P4. Section 3 showed erosive characteristics in the profile P6 and an accumulation tendency in the profiles P7 and P8. The sedimentary characteristics of the area showed distinct distribution patterns as to sand grain size indicating that the coastal sediment transport patterns operating in the area are peculiar to each section studied there being no exchanges between the studied sections. Based on the study results, a zoning of the area has been suggested taking into consideration local geo-environmental units, polluting agents, sea water quality, and vulnerability to erosion. Also, conservation and preservation units have been suggested which make up a sustainability map

ASSUNTO(S)

sustainability evolution geociencias coastline variations progradaÃÃo variaÃÃes da linha de costa accumulation evoluÃÃo sustentabilidade

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