Dinâmica da paisagem no litoral oriental do Rio Grande do Norte: geocartografia e padrões espaciais dos campos de dunas móveis

This study shows the results of a research developed in the coastal regions of the Maxaranguape and Touros municipalities, more specific in the mobile dune fields of the Rio Grande do Norte's eastern coast. Although the coastal zones, represent a small percentage of the earth's surface it concentrates a great part of the world's population. The Rio Grande do Norte's state coastal landscape mosaic composed by the dune fields suggest a dynamic scene of changes in the spatial and temporal arranges, with significant changes in the geometry of the sedimentary cover. Following this perspective this research has the objective to map the emerged coastal zone of the Rio Grande do Norte's eastern coast under the perspective of the time-space evolution of the mobile dune fields using geoprocessing techniques, which includes remote sensing, digital images processing and geographic information system (GIS). The results imply the issue of thematic maps: Geologic map; multitemporal evolution map of the mobile dune fields; quantification of the mobile dune fields differences map; temporal evolution of the mobile dune fields surrounds map. The El Niño episodes have directly affected the atmospheric circulation, what have enhanced the sedimentary input in the sand dune, what can justify the relative area growth between the years of 1993 and 2001. The dynamic of the landscape transition were higher than the stability of the spatial pattern of the dune and it's surrounds, as a result the Rio Grande do Norte eastern coast dune fields, specially the mobile dunes from Touros, Zumbi and Maracajau have shown a decrease on the sedimentary cover without vegetation area from 1970 to 2007. Therefore, the data acquired and the techniques used, can be, eventually applied to the mobile dune fields monitoring in order to preserve the dune ecosystems in the Rio Grande do Norte coast

Experimento de fluxo de sedimentos em um segmento de campo de dunas eólicas costeiras de Jenipabu - Litoral oriental do Rio Grande do Norte.

This study analyzed measurements of the aeolian transport using vertical sand traps across the field dunes of Jenipabu, in the municipality of Extremoz, Rio Grande do Norte state to the North of Natal city. These measurements were used as parameters for the sand aeolian transport in the region. Before the field trips a map of landscape units was made. Three visits to the field were done in September 2011 (field a - the 13th, field b - the 21st, field c - the 29th), period of the year with the highest wind speed, and another in December 8th, 2011 (field d ) when the wind speed starts to decrease. The sand traps used were of the type "I" with collecting opening of 25 cm from the surface level, and type "S" with collecting opening of 25 cm located 25 cm from the surface level in six collecting points in two of the visits (fields a and d ), and sand traps of the type "T" with the collecting opening of 50 cm from the surface level in the other field trips (fields "b" and "c"). A set of records was also collected by using a portable meteorological station complemented with information such as frequency and intensity of winds, precipitation and relative air humidity in the region, from the Estação Meteorológica de Natal , located 12 km from the study area. The sediments collected were treated and the data obtained permitted calculating the ratio of sediment transport. In September, the sedimentation ratio varied from 0.01 to 11.39 kg.m-1.h-1 and in December this ratio varied from 0.33 to 1.30 kg.m-1.h-1 in the type T collectors. In type I collectors they ranged from 0.01 to 11.39 kg.m-1.h-1, while the same parameters varied from 0.01 to 0.73 kg.m-1.h-1 in type S collector. Based on the statistical analysis done, we concluded that the sediment transport increased proportionally to the wind speed 25 cm from the surface. However, this is not true above 25 cm from the surface. The transport of sediments is more intense near the surface where sedimentation ratios greater than 10 kg.m-1.h-1 were found, whilst a maximum value of 3 kg.m-1.h-1 was observed 25 cm below the surface. The volume of sediments collected increases with the increasing wind speed at the surface level, whereas this relationship is opposed far away from that surface

Caracterização geológica tridimensional e monitoramento de dunas no litoral oriental do Rio Grande do Norte

This work presents geophysical and geological results obtained in a dunefield located in the east coast of Rio Grande do Norte State, with the aim to recognize the aeolian body depositional geometries to a future geologic modeling of the aeolian petroliferous reservoirs. The research, which was done in blowouts region situated at Nisia Floresta Municipally, included the characterization of external geometries with GPS and internal geometry analysis by GPR. Data was integrated in GoCAD software, where it was possible the three-dimensional characterization and interpretation of the studied deposits. The interpretation of GPR profiling allowed identifying: First-order bounding surfaces that separated the aeolian deposits of the Barreiras Formation rocks; Second-order bounding surfaces, which limit dune generations and Third-order bounding surfaces, a reactivation surface. This classification was based and adapted by the Brookfield (1977) and Kocurek (1996) propose. Four radarfacies was recognized: Radarfacies 1, progradational reflectors correlated to foresets of the dunes, Radarfacies 2, plain parallels reflectors related to sand sheets, Radarfacies 3, plain parallels reflectors associated to reworking of the blowout dune crest and Radarfacies 4, mounded reflectors associated to vegetated mound of sand or objects buried in subsurface. The GPR and GPS methods was also employed to the monitoring of dunefields susceptible to human activities in Buzios Beach, where the constructions along the blowout region and the tourism are changing the natural evolution of the deposits. This fact possibly to cause negative impacts to the coastal zone. Data obtained in Dunas Park, a unit environmental conservation, was compared with information of the Buzios Beach. There is a major tendency of erosion in Buzios, specifically in blowout corridor and blowout dune

Anatomia e ultra-estrutura foliar de Cyperus maritimus Poir. (Cyperaceae): estratégias adaptativas ao ambiente de dunas litorâneas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo do nicho ecológico de duas aves de rapina (Falco sparverius e Athene cunicularia) em uma região de dunas do Rio Grande do Sul, Brasil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estratigrafia de dunas costeiras de Salinópolis/PA em associação com variações pluviométricas/Bragança-PA

O presente estudo foi realizado no município de Salinópolis, nas praias de Atalaia e Maçarico (PA/Brasil), com o objetivo de se obter um panorama morfo-estratigráfico das dunas costeiras e sua evolução recente na área, avaliando também as correlações com variações climáticas no Holoceno tardio. Na área de estudo foram realizados trabalhos nas dunas transversais e nas dunas parabólicas utilizando-se principalmente perfilagem geofísica com Radar de Penetração no Solo (GPR), sondagens, análises granulométricas e datações. Foi utilizado o sistema GPR digital SIR-2000 com uma antena de 200 MHz, para se obter a estratigrafia dos depósitos dunares, identificando suas fácies estratigráficas e possíveis reativações destas dunas em tempos pretéritos. Testemunhos de sedimentos foram coletados a partir de um sistema de trado manual para complementação, obtenção de material para análises e datações, especialmente nos locais onde os registros de GPR, e consequentemente a estratigrafia, se mostraram interessantes. Na Praia do Maçarico foram identificadas duas cristas de dunas frontais principais, com idades de 69 e 80 anos respectivamente com uma taxa média de progradação de 6 metros/ano. Na praia do Atalaia o cenário apresenta-se com caráter mais transgressivo, onde se observou uma feição provavelmente pleistocênica, embora a datação obtida indique uma idade de apenas 58 anos. A duna parabólica investigada nessa área revelou uma migração da ordem de 4 metros/ano, semelhante à taxa observada na praia do Maçarico e possivelmente correspondendo a fases anuais de migração, que ocorreriam durante o período seco e de ventos mais fortes. A estratigrafia das dunas na área de estudo mostra uma correspondência com as oscilações climáticas sazonais de pluviosidade e ventos, seu uso é de grande potencial para estudos climáticos.