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In the coastal area of Ceará State, northeast Brazil, there are large mobile dunefields, including barchans, barchanoid dunes and sandsheets. The migration rate of these dunes, as measured by several studies, varies between 32 m/y and 9 m/y. This paper analyzes the migration of the dunes in Canoa Quebrada Beach, located in the eastern coast of Ceará State, using remote sensing of aerial photos and satellite imagery from 1988 to 2013 (25 years). The resulting data indicate an average migration rate varying from 1.8 m/y to 9.3 m/y. This is the lowest rate of migration measured for large and undeveloped mobile dunes in Ceará State. The analysis indicates that the element responsible for this low rate is the low wind speed. However, the installation of wind power turbines in the area – which demanded the fixation of part of the dunes to prevent the equipment from being buried and from aeolian erosion – might be another reason for the decreasing dune migration. The dune migration decrease may increase the sedimentary deficit in the coastline downdrift of Canoa Quebrada Beach.

In the coastal area of Ceará State, northeast Brazil, there are large mobile dunefields, including barchans, barchanoid dunes and sandsheets. The migration rate of these dunes, as measured by several studies, varies between 32 m/y and 9 m/y. This paper analyzes the migration of the dunes in Canoa Quebrada Beach, located in the eastern coast of Ceará State, using remote sensing of aerial photos and satellite imagery from 1988 to 2013 (25 years). The resulting data indicate an average migration rate varying from 1.8 m/y to 9.3 m/y. This is the lowest rate of migration measured for large and undeveloped mobile dunes in Ceará State. The analysis indicates that the element responsible for this low rate is the low wind speed. However, the installation of wind power turbines in the area – which demanded the fixation of part of the dunes to prevent the equipment from being buried and from aeolian erosion – might be another reason for the decreasing dune migration. The dune migration decrease may increase the sedimentary deficit in the coastline downdrift of Canoa Quebrada Beach.

Este trabalho apresenta uma análise da geodinâmica e morfogênese do campo de dunas na região de Canoa Quebrada, localizada no município do Aracati, inserido no Estado do Ceará. Abrange a área formada pela planície flúvio-marinha, faixa de praia e campo de dunas localizados na margem direita da foz do rio Jaguaribe. O recorte temporal avaliado corresponde à análise da dinâmica do campo de dunas com base nas taxas de migração no período de 1988 a 2013. Os objetivos dessa pesquisa foram analisar a dinâmica ambiental do campo de dunas móveis em direção ao ecossistema manguezal localizado na foz do rio Jaguaribe. Associado à abordagem metodológica, realizou-se geoprocessamento de fotografias aéreas da década de 80 na escala de 1:25.000 e imagens de satélites Quickbird dos anos de 2004, 2010 e 2013. Foram identificadas dunas móveis do tipo longitudinais, barcanóides e lençóis de areias. Do ponto de vista de cobertura vegetal, foram identificadas dunas semi-fixas no contato com o ecossistema manguezal. Quanto às gerações dunares, domina a geração D1, caracterizada pela ocorrência de dunas atuais, móveis. No contato com o ecossistema manguezal, as dunas semi-fixas se combinam com a geração de dunas anteriores às atuais, do tipo sub-atuais, definindo a existência de dunas de geração D2. A taxa média de migração no campo de dunas durante todo esse período de 40 anos foi de 7m/ano. Nos anos de 2010 a 2013 praticamente não ocorreu migração, mas as dunas continuam se deslocando em direção ao ecossistema manguezal.Palavras chaves: Dunas costeiras, geodinâmica; morfogênese de dunas.ABSTRACTThis paper presents an analysis of geodynamic and morphogenesis of the dune field in the Canoa Quebrada region, located in the municipality of Aracati, inserted in the state of Ceará. It covers the area formed by fluvial-marine plain, the strip of beach and dune field located on the right bank of the mouth of the river Jaguaribe. The estimated period corresponds to the dynamic analysis of the dune field based on migration rates from 1988 to 2013. The objectives are to analyze the environmental dynamics of the mobile dune field towards the mangrove ecosystem located at the mouth of the river Jaguaribe. Associated with the methodological approach, we analyzed through GIS aerial photographs of the 80 on the scale of 1: 25,000 and 2004, 2010 and 2013 years of Quickbird satellite images. We find mobile dunes of the longitudinal type, barcanoids and sand sheets. Semi-fixed dunes were identified in the contact with the mangrove ecosystem. As for dune generations, we can say that dominates the generation D1, characterized by the occurrence of present-day dunes. In the contact with the mangrove ecosystem, the semi-fixed dunes combine with older dunes to define the existence of D2 generation. The average migration of the dune field during that period of 40 years was 7m / year. In the years 2010-2013, virtually no migration occurred, but the dunes continue to move towards the mangrove ecosystem.Keywords: Coastal dunes, geodynamics; dune morphogenesis.