Aspectos geoambientais entre as praias do Paiva e GaibÃ, MunicÃpio do Cabo de Santo Agostinho (Litoral sul de Pernambuco)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The present work is a result of a systematic study of the erosive processes constraints along the coast between Paiva Beach and Cabo de Santo Agostinho promontory, Pernambuco, including the adjoining continental shelf. A diagnostic focused on the geologic characteristics of the coastal zone, including the emerse and submerse areas, on the vulnerability characteristics and on the coastal line evolution in the medium and short time was undertaken. Sedimentologically, in the backshore occurs sands with 0.250 mm, in the beach occurs sands between 0.250 and 0.125 mm and in the foreshore sands between 0.125 and 0.050 mm. Radiometric studies showed that heavy minerals deposition was more frequent in the Gaibu beach (750 cps reading) and that the placer deposits are superficial. Mainly sand and gravel sands cover the inner continental shelf. Multivariate analysis distinguished the environmental condition in the depositional systems in which marine processes prevailed. The bottom morphology shows two distinct patterns. In the northern part there is an irregular bank trending N-S, limited by the 12 m isobatimetric line, whereas to the south occurs deep depressions. Regarding the Dean parameter, the beach state was classified morphologically as intermediate. In the medium term it was possible to identify areas where the coastal line was stable and areas where it retreated and forwarded, establishing critical areas regarding coastal erosion in the last three decades. Progradation areas represent 78% whereas eroded areas correspond to 22% of the studied area. Monitoring, through the topographic leveling in the cross-section considered, showed a short-term erosion with an erosion rate between 1.02 m3/m and 76.4 m3/m. The vulnerability behaved mainly as a low-grade vulnerability. The progressive land occupation increase may cause an interruption in the sediment flux in the studied area

ASSUNTO(S)

sedimentologia, variaÃÃes da linha de costa, erosÃo, plataforma, batimetria vulnerabilidade geociencias sedimentology, coastal line variations, erosion, shelf, batimetry and vulnerability

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