Resumo:Processos erosivos podem ser identifi cados por meio de geoindicadores. O presente estudo classifi cou geoindicadores decorrentes da erosão no litoral de Pernambuco, no nordeste brasileiro. A metodologia foi baseada na detecção em campo da presença ou ausência de dez indicadores de erosão previamente descritos na literatura como recorrentes no litoral brasileiro. Estes indicadores foram agrupados em 4 classes de intensidade, sendo: nula (sem geoindicadores), baixa (geoindicadores ecológicos que não alteram signifi cativamente a paisagem), moderada (geoindicadores morfológicos que alteram significativamente a paisagem) e alta (geoindicadores causados pela ação antrópica). Os principais geoindicadores observados foram: pós-praia estreito ou inexistente, escarpa erosiva nas dunas, obras estruturais de proteção costeira, e árvores na face de praia ou com raízes expostas. Ao longo dos 172 km de praias arenosas do estado de Pernambuco foi identifi cado que 48% não apresentaram nenhum geoindicador de erosão, 8% apresentaram geoindicadores de baixa intensidade, 16% de moderada intensidade e os demais 28% apresentaram geoindicadores de alta intensidade de Informações sobre o ArtigoRecebido

No abstract

This paper evaluates the effect of a fringing reef on the morphodynamic behaviour of adjacent beaches in terms of profile stability and cross-shore sediment exchange. Variations in subaerial beach morphology along 39 crossshore profiles at Pontal do Cupe beach (Northeastern Brazil) were analysed, using modelled wave data and monthly beach topography acquired from November 2014 to September 2016. Pontal do Cupe has a reef to the south but is exposed to waves in the north, making this an ideal location to assess the sheltering effect of the reef. Beach volume and beach width data were used to compare the reef-fronted profiles with those of the exposed adjacent beach. Seven groups of profiles were identified by applying Principal Component Analysis to the topography dataset. A simple numerical model was used to quantify the role of the reef in dissipating wave energy, showing a reduction of approximately 50% in incoming wave energy to the shore. The reef-fronted beach is significantly more stable than the exposed beach. Total beach volume is similar for both the exposed and the reef-fronted beach. The results of this survey can be used as a proxy for the ecosystem service of coastal protection provided by reefs.

This article concerns the erosion at Pau Amarelo Beach in Pernambuco, Brazil. The maintenance of this beach is important for tourists and the community and is significant for the local economy. Pau Amarelo is a highly urbanized area with poor coastal plain. The coast is characterized by the presence of lined reefs running along the shore. In order to understand the causes of the erosion at this site, coastline variation, the displacement of urban areas and wave characteristics were analyzed. It is believed that both the human incursions on the backshore and the intensification of longshore currents in some parts of the coast, caused by wave diffraction at the reefs, contribute to the beach erosion. The breakwaters built south of Pau Amarelo are also believed to decrease sediment transport by blocking the drift current. Beach nourishment is suggested as the most suitable solution to the erosion at Pau Amarelo. ADDITIONAL INDEX WORDS:Beach erosion, anthropic effects, numerical wave modeling, coastal hydrodynamic, longshore currents.